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System 8813 Macro Assembler - PolyMorphic

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1. COUNT SET COUNT 1 repeatl 1 DB 1 ENDIF ENDM repeat 2 HI Build 3 HI s COUNT SET 2 repeatl HI IF COUNT COUNT SET COUNT 1 repeatl HI IF COUNT gt 2 COUNT SET COUNT 1 repeatl HI IF COUNT COUNT SET COUNT 1 repeatl HI DB HI ENDIF DB HI ENDIF DB Page 54 3216 FFFF 3219 FFFF 321C 321F 0090 FFFF 3222 3226 FFFF 3227 322B FFFF 322C 3230 FFFF 3231 3235 3236 323A 464F4F 464F4F 464F4F 464F4F 57495A4C 45 57495 4 45 57495 4 45 57495A4C 45 57495A4C 45 MACRO 88 Assembler Manual ww w Se Se E LII s 4 Se Se os PolyMorphic Systems Another way to do it this one less saving of MSTACK space We pass the updated count to the next lower macro call in a parameter The count for each level must be stored on the MSTACK so we run out of storage quicker MACRO IF DB many ENDIF It does look better though 1 gt 0 2 1 1 2 4 FOO 4 gt 4 FCO 4 1 FOO 4 1 gt 0 FCO 4 1 1 4 1 1 gt 0 FOO 4 1 1 1 FOO 4 1 1 1 gt 0 FOO 4 1 1 1 1 FOO 4 1 1 1 1 gt 0 FOO 4 l 1 1 1 1 FOO Pretty slick huh Here is what happens if you call too many macros fram inside a macro The MSTACK overflows many 9 WIZLE 9 0 WIZLE 9 1 WIZLE 9 1 0 WIZLE 9 1 1 WIZLE 9 1 1 0 WIZLE 9 1 l l WIZLE 9 1 1 1 50 WIZLE 9 1
2. MACTYPE MACTYPE LEN wow LEN MVI A CR CALL WHQ CR 4 LEN wow wow MACTYPE MVI A I CR CALL WH2 CR GET OPCTYPE 2 OPCTYPE OPCTYPE LEN GET 7 GET OPCTYPE Page 59 329F 01 32A0 0200 0000 32A2 40 MACRO 88 Assembler Manual DW IF ELSE ENDIF ELSEIF POPGEN SET GETCODE EQU DB ELSEIF DB ENDIF PolyMorphic Systems 2 NOT NULL g OPCTYPE POPTYPE Pop type POPGEN 1 POPGEN LEN GET 6 LEN GET GET GETCODE OPCTYPE MACTYPE LEN GET LEN 2 44 LEN GET GET MACTYPE 2 Page 60 MACRO 88 Assembler Manual Error total 1 Macros defined in this assembly bizzarre define first flap listxmpl many params repeat repeatl second symel Set variables used COUNT 0000 FALSE 0000 POPGEN Labels defined in this assembly CR 0000 LABl 320B MACTYPE POPTYPE 0002 PRBASECODE 0001 PolyMorphic Systems 9001 TRUE FFFF 0008 OPCTYPE 9001
3. 256 LABELSYM AND FFH backwards address For more information on the format of a string see Section 2 2 1 4 on short strings used in expressions 2 2 4 File Name Operands On the System 88 there is a special format for specifying a disk file This format known as a file specifier has been transferred to the syntax of some of the operands for pseuo ops that need to work with disk files REFS and DEFS pops use these operands They are described in detail in the System 88 User s Manual but are shown here for completeness The format looks like lt optional drive number Filename EX where the optional drive number is a single digit from 1 through the highest drive number the Filename is a character sequence up to 3l characters long and EX is a two character extension that indicates the file type The System Drive is the default drive its number need not be stated If the drive number is omitted the angle brackets are too Some examples Page 18 MACRO 88 Assembler Manual PolyMorphic Systems amp 3 Bingo Ive got it TX text file on disk in drive 3 lt 2 gt HELLO GO object code file on disk in drive 2 MY SYMBOLS SY a file on System Drive with the SY extension used by the REFS and DEFS system 2 3 OPCODES AND PSEUDO OPCODES This section discusses the function of opcode statements which generate machine instructions in the binary output file and pseudo opcode statements assembler directives 2 3 1 T
4. 0 0 11 BAD INDEX INTO SYMBOL DATA FIELD 0 04 11 STINSERT CONFUSED 6CO5 SYMFIND CAN T FIND SYMBOL 0001 Number has illegal digit 00022 Base is out of range must be 2 gt 36 0003 11 PRINT FIELD ERROR IN NUM 0004 Number has value gt 65535 gE01 LABEL HAS NO ENTRY IN PASS 2 0 01 ENDM without previous MACRO OFO2 PSEUDO OP HAS ILLEGAL SUBTYPE CODE 1001 Cannot ORG backwards ORG ignored 1161 Undefined symbol reference 1102 Illegal symbol type reference 1203 Value gt 255 truncated to eight bits 1361 Cannot redefine system symbol 1302 Doubly defined symbol 1393 Cannot SET a previously defined LABEL 1304 Cannot use a SET VARIABLE as a LABEL 1306 Phase error sym val changed in pass 2 1501 ENDIF ELSE ELSEIF without IF 1601 Statements found after END 1761 Double definition by REF 1702 REF without previous REFS 1703 REF LOST DEF BETWEEN PASSES 1 1764 Symbol not found in REF file 1801 1 DEF CAN T FIND SYMBOL 1802 DEF given an undefined symbol 1803 DEF given a doubly defined symbol 1864 DEF without previous DEFS 1805 REF DEF without symbol name Systems Page 43 MACRO 88 Assembler Manual PolyMorphic Systems 1901 Parm list unmatched brackets 1942 Parm list unmatched quotes 2061 MSTACK overflow Sorry 2002 MPEEK BUFFER SHORT 2003 MACPOP DE 2201 Illegal character after 89080 111 No message for this error Any unlisted code gives a
5. 1 1 1 WIZLE 9 1 1 1 120 WIZLE Page 55 323 323 FFFF 3240 3244 FFFF 3245 3249 324A 324E 3252 3255 3259 325D 57495A4C 45 57495 4 45 57495 4 45 MACRO 88 Assembler Manual many IF DB many IF DB many IF DB many PolyMorphic Systems 9 1 1 1 1 1 WIZLE 9 1 1 1 1 120 WIZLE 9 1 1 1 1 1 1 WIZLE 9 1 1 1 1 1 1 0 WIZLE 9 1 1 1 1 1 1 1 WIZLE 9 1 1 1 1 1 1 120 WIZLE 9 1 1 1 1 1 1 1 1 WIZLE ERROR 2001 MSTACK overflow Sorry 46495253 54204D41 43524F 5345434F 4E442904D 4143524F t r ENDIF ENDIF ENDIF ENDIF ENDIF ENDIF ENDIF ENDIF Now we use a macro to define two other macros This is primarily an exercise but should help the user gain confidence in the system etc define MACRO first MACRO DB ENDM second MACRO ENDM ENDM define first MACRO DB ENDM second MACRO e sa c 9A Se we DB ENDM FIRST MACRO SECOND MACRO FIRST MACRO SECOND MACRO Now the two macros should be available first DB second FIRST MACRO SECOND MACRO In order to control the printing of macros the MACLIST pseudo op can be used with an argument that is an expression If the expression evaluates to FALSE Page 56 3261 48492954 3265 48455245 MACRO 88 Assembler Manual PolyMorphic Systems 0000 then macros are
6. A L 9D SBB L BD L 5E MOV 7E MOV A M 9E SBB M BE CMP M SF MOV E A 7F MOV A A 9F SBB A BF CMP A All flags C Z S P AC affected Page 46 RETURN 9 RET Cg RNZ C8 RZ 00 RNC D8 RC ES RPO E8 RPE RP F8 RM ACC IMMEDIATE C6 ADI d8 CE ACI d8 D6 SUI 48 DE SBI d8 E6 ANI d8 EE XRI 48 F6 ORI d8 a INCREMENT 04 INR B C INR C 14 D INR E 24 INR H 2C INR L 34 INR M 3C INRA 03 INX B 13 INX D 23 INX H 33 INX SP Adr a H H M H 88 Assembler Manual 16 bit address All flags 2 5 affected Only CARRY flag affected All flags except CARRY affected exception affect no flags Constant or logical arithmetic expression that evalu LOAD STORE LDAX B 1 LDAX D 2A LHLD Adr 3A LDA Adr 02 STAX B 12 STAX D 22 SHLD Adr 32 STA Adr LOAD IMMEDIATE 01 LXI B dl6 Il LXI D dl6 21 LXI H dl6 31 LXI SP dl6 INPUT OUTPUT D3 OUT d8 DB 48 STACK OPS CS PUSH B 05 PUSH D E5 PUSH H F5 PUSH PSW Cl POP B Dl POP D El POP E Fl POP PSW XTHL F9 SPHL ates to an 8 bit data quantity dl6 Constant or logical arithmetic expression that evalu ates to a l6 bit data quantity PolyMorphic Systems RESTART C7 RST 9 CF RST 1 D7 RST 2 DF RST 3 E7 RST 4 EF RST 5 F7 RST 6 FF RST 7 SPECIALS EB XCHG 27 DAA 2F CMA 27 864 JF a DECREMENT 05 DCR B D DCR C 15 DCR D 1D DCR E 25 DCR H 2D DCR L 35 D
7. C INR C 2C INR L 4C MOV C H 6C MOV L H 00 DCR C 2D DCR L 4D MOV C L 6D MOV L L BE MVI 48 2E MVI L d8 4E MOV 6E MOV L M F RRC 2F CMA 4F MOV C A 6F MOV L A 19 30 50 MOV D B 70 MOV M B ll LXI 416 31 LXI SP dl6 51 MOV D C 71 MOV M C 12 STAX D 32 STA Adr 52 MOV D D 72 MOV M D 13 INX D 33 INX SP 53 MOV D E 73 MOV M E 14 INR D 34 INR M 54 MOV D H 74 MOV M H 15 DCR D 35 DCR M S5 MOV D L 75 MOV M L 16 MVI D d8 36 MVI M d8 56 MOV D M 76 HLT 17 RAL 37 STG 57 MOV D A 77 MOV M A 18 38 58 MOV 78 MOV A B 19 DAD D 39 DAD SP 59 MOV E C 79 MOV 1A LDAX D 3A LDA Adr 5A MOV E D 7A MOV A D 1B DCX D DCX SP 5B MOV E E 7B MOV A E IC INR 3C INRA 5C MOV E H 7C MOV A H 1D DCRE 3D DCRA 5D MOV E L 7D MOV A L 1E MVI E d8 MVI 48 5E MOV E M 7E MOV A M lF RAR 3F CMC 5F MOV 7F MOV A A 316 Constant or logical arithmetic expression that evalu ates to a 16 bit data quantity d8 Constant or logical arithmetic expression that evalu ates to an 8 bit data quantity Adr 16 bit address Page 49 80 ADD 81 ADD 82 ADD B3 ADD 84 ADD 85 ADD 86 ADD 87 ADD 88 ADC 89 ADC 8A ADC 8B ADC 8C ADC 8D ADC 8E ADC 8F ADC 90 SUB 91 SUB 92 SUB 93 SUB 94 SUB 95 SUB 96 SUB 97 SUB 98 SBB 99 SBB SBB 9B SBB 9C SBB 9D SBB 9E SBB 9F SBB Adr 38 316 MACRO 88 1 2 4 5 6 7 8 9 AD AE AF Ba Bl B2 B3 B4 BS B6 B7 B8 B9 BA BB B
8. are printed four to a line The base of the value printout is settable by the user and thus may change shortening or lengthening the whole line With base 16 hexadecimal normal default the print line is 64 characters Page 49 MACRO 88 Assembler Manual PolyMorphic Systems long and looks good on the video display Thus Error total 3 Macros defined in this assembly big lpg db sort Undefined symbols DEFSCLOSE PLOVER READC Doubly defined symbols DOORG2 0456 SET variables used NCOUNT 00801 BCOUNT 0005 Labels defined in this assembly ADDEXPR 3C5D ADDLI 47BB ADDLIST 47A5 ADDRCODE 0002 ADDRTYPE 4589 ADRTP1 458F AFIELD 5161 AFLDBLK 5163 and so on The base of the number printout is the same as the last base used for the assembly object code printout This is settable by the user through the PRBASE pseudo op Page 41 MACRO 88 Assembler Manual PolyMorphic Systems Appendix A ERROR MESSAGES Error messages included the MACRO 88 Assembler are shown be low with the internal codes generated by the assembler The actual message text is generated by the Amsg OV overlay when it is passed the error code Error messages in upper case are error system errors and should never be seen by the user If you do get an all capital error message or the message 1111 No message for this error 1111 please contact PolyMorphic Systems to report a system bug The proper procedure is to fill out an SIDR form Software Improve ment or Difficul
9. is printed PRBASE changes the address and object code print outs on the assembly source listing Also the base of the value field of each element in the symbol table printout is given by the last PRBASE in the program See Section 1 4 on the assembly listing for more information on the effects of the base change by the PRBASE pseudo op The default print base is 16 hexadecimal 2 3 2 14 LIST The jennen form for the LIST pseudo op is lt optional label gt LIST expression If the value of the expression is zero the assembly listing is suppressed If the value of the expression is non zero the assembiy listing is turned back on or if already on is left on The default condition is as if a LIST 1 had been executed just before the user s source code is read in other words the assembly source listing will normally not be supressed unless a LIST 0 is found A common way to use the LIST pop is to have the expression be a set variable or a label symbol whose value nas been defined by an EQUate pop at the beginning of the program In this way the programmer can make control structures that allow him to prevent selected sections of his program from being printed by merely changing the value of the EQUate symbol For example HELPLIST EQU 1 Print the HELP subroutine LIST HELPLIST HELP the code for the HELP subroutine List 1 will print the HELP subroutine only if the HELPLIST symbol is Page 26 MACRO 88 Assemb
10. se Sa Se S x coo s params MACRO 1 2 7 A ENDM params 1 2 71 72 71 2 params 1 2 s 2 2 2 2 params A B C D E F Page 57 2000 0001 2002 0008 MACRO 88 Assembler Manual 7A B C D E F params A B C 7D A B C D params 7A 7B 7A B params 3A 7B params lt Se Se Se Se 098 wa Se wa 4 Se 9a 9a Sa Sa 2 x T B 9 POPTYPE EQU symel MACRO IF IF DB ELSE ENDIF ELSEIF POPGEN SET 1CODE EQU DB PolyMorphic Systems A B C D A B A B There are two parameter functions in MACRO 88 version 002 The LEN function returns the number of bytes memory that would be taken up if its argument were submitted to a DB pseudo op LEN can be used anywhere an expression is permitted Its value is 16 bits long but can be shortened as any other 16 bit value can by putting it in a DB pop The NULL function checks its argument for existence The argument can be one or more comma separated Parms each constructed according to the rules as described above If any parm can be extracted from NULL s arguments the value is 0900H Otherwise the value is OFFFFH Here is an example which builds entries in the MACRO 88 initial symbol table An entry is specified by the 16 bit total length the 8 bit name length the ASCII name the type code byte and the variable length data field which is 16 bits except fo
11. setting the single set variable will control the printing of all the associ ated macros If the macros do not use this convention they can all be controlled at once with the MACLIST at the top of the program or individually by separate MACLIST pops before each macro reference 2 3 2 5 SET The SET pseudo op has the form lt symbol name gt SET lt expression gt It is used for defining the value of a special kind of symbol known aS a set variable Set variable symbols can be redefined during assembly no doubly defined symbol error will result as with normal label symbols The first time the SET pop is used the new variable is created and each subsequent time it is used the value will just be changed The set variable sym bol can be used in an expression for an operand anywhere a label symbol can be used If a set variable is used before it is de fined no error results and an undefined value is used in the reference If a set variable is redefined as a label after it has been created an error results ERROR 1304 Cannot use a SET VARIABLE as a LABEL If a label symbol is redefined as a set variable using the SET pop this error results ERROR 1303 Cannot SET a previously defined LABEL 2 3 2 6 DS The form of the DS Define Storage pseudo op is lt optional label gt DS lt expression gt The expression value is used as a skip distance the location counter will advance that number of bytes before the next
12. start address may be any address at all but is most often the first instruction in the program The fourth byte of the program is assumed to be the warmstart location of programs which run in user memory space This means that if for any reason the program is interrupted it can be re Started without its re initializing all of its internal data areas For example a text editor should restart with its text buffer containing the text that was in it when the editor was exited The use of byte four comes about due to the convention of having a JMP START followed by a JMP WARM as the first two instructions of a user program Thus the first few instructions of programs to be run in user space usually look like Page 33 START WARM MACRO 88 Assembler Manual PolyMorphic Systems ORG 32008 Start of user space in memory IDNT START La 32008HB Sa START JMP START Redundant for START command JMP WARM For REENTER command REFS SYSTEM SY Open the system library REF ion Start getting globals Entry point for complete initialization Entry point for clean re initialization Page 34 MACRO 88 Assembler Manual PolyMorphic Systems Page 35 MACRO 88 Assembler Manual PolyMorphic Systems Section 3 RUNNING THE ASSEMBLER This section discusses the activity called running the assembler or doing an assembly The purpose of running the assembler of course is to produce a correctly translated object code pro gram suitabl
13. statement If the assembler runs out of input text before it finds the mandatory END statement it assumes that there is a continuation file where the rest of the input text can be found It will ask you to specify the name of the continuation file You take this opportunity to exchange disks in the drive if necessary and then type in the name of the continuation file When the END statement is finally found you replace the original disk and re specify the original source file If the END statement is found on the first source file the assembler will immediately rewind and start pass two automatically 1 4 THE ASSEMBLY LISTING You will probably want to make a listing of your program while it is being assembled The assembly listing shows the original program as well as the translation of it It serves as a base for your bug hunting efforts MACRO 88 writes out listings through the system s standard printer wormhole port to a line printer of some kind The listing also includes error summaries symbol table printouts the number of errors assembled and so on A section of a typical assembly listing is shown below This is the portion of the listing that shows the object code and the original text or source code Note that each kind of information item falls into its own field Page 4 MACRO 88 Assembler Manual PolyMorphic Systems 3367 3AD34C SCNPT LDA BSAVE Is there any more t 336A 7 ORA A 336B C8 RZ 336C 3D DCR A
14. the four pops is IF lt expr gt subsection A gt ELSEIF lt expr gt subsection B ELSEIF lt expr gt ELSE lt default subsection gt ENDIF A This structure will select one and only one subsection of the IF ENDIF delimited area to be assembled All the other sub sections are skipped The conditions that are tested have a priority structure if any lt expr gt fails evaluates to zero then the rest of the tests are ignored Conversely if any test is to be made all the lt expr gt s above it must have failed The subsection delimited by the ELSE ENDIF combination denotes the default condition for this structure as it is the section which will always be assembled if all the others are skipped Any of the subsections may contain another IF ENDIF pair or a structure similar to the one above nested up to the depth limit of 256 levels 2 3 2 12 PAGE The PAGE pop is invisible it does not appear on the listing However it is apparent whenever it has been used because after a PAGE the listing skips to the top of the next page before con tinuing When the listing is being put on the video display rather than the printer PAGE is not invisible and has no effect Form lt ignored optional label gt PAGE lt optional ignored comment gt Page 29 MACRO 88 Assembler Manual PolyMorphic Systems 2 3 2 13 Library system pops Normally the problem of assembling extremely large programs is handled by providing a lin
15. the parentheses are not paired properly we get ERROR 0201 Expression has unbalanced parentheses 2 2 1 6 1 Arithmetic Operators Arithmetic operators all operate on 16 bits at once Some oper ate as if their operands were two s complement binary integers others as if they were positive binary integers some operators work just as well when their operands are considered to be either The arithmetic operations unary MOD SHL and SHR Page 14 MACRO 88 Assembler Manual PolyMorphic Systems Addition works on positive numbers but since two s complement numbers can be added as if they were positive it works just as well for them If the result of addition is greater than 65535 then it cannot be expressed in 16 bits so this error results ERROR 0 01 Number has value gt 65535 Since a two s complement number cannot exceed 32767 or 32768 without having a non zero bit 17 the error detection works properly for both number systems Subtraction and unary minus X both assume their operands are two s complement numbers Subtraction is exactly equivalent to negation using unary minus followed by addition using the addi tion described above Thus the overflow error message works according to the add Unary minus is exactly equivalent to a logical complementing of each bit followed by an incrementing by one using the add X Y gt X t Y Definition of subtraction Y gt NOT Y 1 Defi
16. C BD BE BF P rt m m O G m p t ta O O J p X rtm cU ou x t z 1 D G ANA ANA ANA ANA ANA ANA ANA ANA XRA XRA XRA XRA XRA XRA XRA XRA ORA ORA ORA ORA ORA ORA ORA ORA CMP CMP CMP CMP CMP CMP CMP CMP 16 bit address Assembler Manual gt p i m g O m gt gt t i 1 OQ D xrt unp D O ID gt X r m 3 D G J RNZ POP B JNZ Adr JMP Adr 2 Adr PUSH B ADI d8 RST RZ Adr RET JZ Adr CZ Adr CALL Adr ACI 48 RST 1 RNC POP D JNC Adr OUT d8 CNC Adr PUSH D SUI d8 RST 2 RC JC Adr IN d8 CC Adr SBI d8 RST 3 PolyMorphic Systems El 2 4 5 E6 E7 E8 E9 EA EB EC EE EF F9 Pl F2 F3 F4 FS F6 F8 F9 FA FB FC FD FE FF RPO POP H JPO Adr XTHL CPO Adr PUSH H ANI d8 RST 4 RPE PCHL JPE Adr XCHG CPE Adr XRI d8 RST 5 RP POP PSW JP Adr DI CP Adr PUSH PSW ORI 48 RST 6 RM SPHL JM Adr EI CM Adr CPI d8 RST 7 Constant or logical arithmetic expression that evalu ates to an 8 bit data quantity Constant or logical arithmetic expression that evalu ates to a 16 bit data quantity Page 580 88 Assembler Manual PolyMorphic Systems Page 51 MACRO 88 Assembler Manual PolyMorphic Systems Appendix E SAMPLE PROGRAM The following program was assembled using the MACRO 88 Assembler It illustrates some of the techniques the assembler makes possible Page 52 MACRO 88 Assembler Manual PolyMor
17. CR M 3D DCRA 0B DCX B 1B DCX D 28 DCX H 3B DCX SP INX amp DCX Page 47 MACRO 88 Assembler Manual PolyMorphic Systems JUMP MOVE IMMEDIATE CALL C3 JMP Adr 06 MVI B d8 CD CALL Adr C2 JNZ Adr JE MVI 48 C4 CNZ Adr CA JZ Adr 16 MVI D d8 CC eZ Adr D2 JNC Adr lE MVI E d8 D4 Adr DA JC Adr 26 MVI H d8 DC CC Adr E2 JPO Adr 2E MVI L d8 E4 CPO Adr EA JPE Adr 36 MVI M d8 EC CPE Adr F2 JP Adr 3E MVI A d8 F4 CP Adr FA JM Adr FC CM 9 PCHL DOUBLE ADD CONTROL ROTATE 29 DAD B 00 07 RLC 19 DAD D 76 HLT F RRC 29 DAD H DI 17 RAL 39 DAD SP FB lF RAR FLAG BYTE STACK FORMAT 7 6 5 B 3 2 1 4 5 2 g A 0 P 1 C 16 bit address 38 Constant or logical arithmetic expression that evalu ates to 8 bit data quantity Only CARRY flag affected Page 48 MACRO 88 Assembler Manual PolyMorphic Systems REFERENCE LIST NUMERICAL LISTING OF THE 8080 INSTRUCTION SET 00 20 40 66 MOV H B 01 LXI 416 21 LXI 416 4l MOV B C 61 MOV H C 02 STAX B 22 SHLD Adr 42 MOV B D 62 MOV H D 63 INX B 23 INX H 43 MOV B E 63 MOV H E 04 INR B 24 44 MOV B H 64 MOV H H 05 DCR B 25 DCR H 45 MOV B L 65 MOV H L 66 MVI 48 26 MVI 48 46 MOV 66 07 RLC 27 DAA 47 67 08 28 48 68 MOV L B 09 DAD B 29 DAD H 49 MOV C C 69 MOV L C A LDAX B 2A LHLD Adr 4A MOV C D MOV L D B DCX B 2B DCX H 4B MOV C E 6B MOV L E
18. Continuation file if an ENDM is left off a macro definition that seems to merit one This results because it is allowable to put the END pop inside a macro definition Leaving off ENDM just makes the definition very long 2 3 2 4 3 MACLIST MACLIST has the form MACLIST lt expr gt MACLIST has the same form as LIST and in fact has a similar effect The difference is that it affects only the listing of macro expansions where LIST controls the listing of all listing lines j Like LIST MACLIST sets an internal variable according to the value of the expression in the operand field But this variable is distinct from the LIST variable so they may have different values During macro expansion the value of the LIST variable is saved and set to the value of the MACLIST variable When the expansion ends the old value of LIST is replaced Some useful capabilities arise from this scheme Inside a par ticular macro for example the LIST pop can be used to control Page 23 MACRO 88 Assembler Manual PolyMorphic Systems the listing of the text of the macro itself But when the macro is done expanding the outside text will continue as it was be fore either being listed or not A typical technique is to use inside the macro a LIST pop with operand field containing the name of a set variable that is used to control the printing of a certain class of macros maybe all the macros gotten from a particular library At the top of the program
19. DEF pseudo op The extension of SY see The System 88 User s Manual for information on extensions is standard for library files When no extension is given for the file name in DEFS SY is used by default one is given it is used instead If the file to be opened already exists or amp f the name is illegally constructed or if for any other reason the system cannot open the desired file the assembly terminates and the appropriate System 88 error message is printed on the video display Each use of DEFS closes a previous DEF file if one was open If a DEF file is still open at the end of an assembly it is closed automatically 2 3 2 13 4 DEF The form of the DEF Define pseudo op is lt optional ignored label gt DEF lt symbol name operand gt The DEF pop is used to write the definition of the symbol whose name appears in the operand field out to the symbol table file currently open see DEFS above If the symbol with the given name is not defined in the program we get ERROR 1802 DEF given an undefined symbol If the symbol given has been defined twice or more in the pro gram then we get ERROR 1803 DEF given a doubly defined symbol Page 32 88 Assembler Manual PolyMorphic Systems If the DEF pop is used before a valid DEF file has been estab lished by the DEFS pop then the error ERROR 1804 DEF without previous DEFS results The REF DEF combination is very powerful in that it can
20. HE ASSEMBLER DOES The purpose of an assembler is to simplify the creation of object code programs An object code program is a sequence of data bytes which can serve as instructions for the CPU directly No matter what computer language a program is first written in the processor can understand only object code machine language so an object code program is the final step of any translation process that is supposed to produce runnable programs An as sembler translates assembly language statements into object code The assembler is a special kind of translator in that there is a one to one correspondence between the assembly language statements of the program you write and the object code statements that the assembler produces Thus when the programmer writes an assembly language program he knows exactly what machine instructions will go to the processor and in exactly what order and exactly where each instruc tion will be in memory when the program is loaded This control over the final object code gives the assembly language programmer great power over the computer s operations Anything that can be translated into an object code program by any language translator can be written in assembly language although with some perhaps vast increase in the length of the program text The special power of assembly language that makes it the almost universal choice of systems programmers is that it enables them to write very efficient prog
21. MACRO 88 Assembler Users Guide PolyMorphic Systems 460 Ward Drive Santa Barbora Califomia 9311 805 967 2351 The MACRO 88 Assembler described in this manual was created by Roger L Deran The assembler is provided as a standard part of the System 88 System Disk which is available in four versions PolyMorphic Systems part no 000386 which provides eight digits of precision in software 000389 fourteen digits in software 000502 which provides eight digits of precision in hardware and 000503 fourteen digits in hardware This manual is Poly Morphic Systems part no 810146 Copyright 1978 Interactive Products Corporation All rights reserved Page 1 MACRO 88 Assembler Manual PolyMorpnic Systems Section l THE MACRO 88 ASSEMBLER INTRODUCTION MACRO 88 is an assembler that runs on the PolyMorphic Systems System 88 line of microcomputers which use the 8080 micro processor and flexible disk drives The System 88 computers have their own characteristics inherited in part from the disk drives the architecture of the microprocessor the organization of the main bus the S 100 used in the system and the struc ture of the System 88 disk operating system The characteristics of any system help to determine the character of any large pro gram written to run on it and this assembler is no exception This section discusses not only the actual assembler but also some reasons why it is the way it is 1 1 WHAT T
22. Yes count it 336D 32D34C STA BSAVE 3370 7 If TAB go scan for a 1 5 MACROS The MACRO 88 Assembler includes macros or ways to name a block of program text so that it can be used later simply by referring to it by name Doing this involves the use of two pseudo ops MACRO and ENDM which begin and end the defined block of text A block of text so defined by MACRO and ENDM can then be used by using its name in a statement as if it were an instruction Macros are explained at length in Section 2 3 2 4 Page 5 MACRO 88 Assembler Manual PolyMorphic Systems Section 2 ASSEMBLY LANGUAGE PROGRAMMING This section discusses the form and meaning of the statements that MACRO 88 accepts and translates It assumes that you are already familiar with the function of the 8080 instructions them selves and only need to know how to make the assembler generate the desired instructions 2 1 ASSEMBLY LANGUAGE STATEMENTS An assembly language program is written as a sequence of state ments corresponding to the sequence of instructions the program mer wants to have in memory when the object code program is loaded in to be run MACRO 88 translates the statements one by one and writes the resulting object code data to the object code file byte by byte Thus when the object code file is loaded into memory the sequence of intructions is the same as the sequence of statements in the source text 2 1 1 Statement Fields Statemen
23. aluates to If the symbol name has already been used for a label or in another equate a double definition error results 2 3 2 2 ORG The ORG Origin pop has the form lt optional label gt ORG lt expression gt The value of the expression is used as the new assembly location Enough zeroes are put into the object code file to fill the space from the address of the last instruction assembled before Page 20 MACRO 88 Assembler Manual PolyMorphic Systems the ORG pop to the address given by the expression in the ORG Instructions generated after the ORG will thus be loaded start ing at this address Note that there is no way to skip back wards since the assembler can only ouput more object code and cannot retract what it has previously output If the value of the expression is less than the current location counter we get an error ERROR 1001 Cannot ORG backwards ORG ignored However if the backwards ORG occurs before any code is gener ated MACRO 88 will allow it and will only change the location counter This makes it possible to put a group of DS statements in an area of memory beyond the program area but to have these DS statements occur at the front of the program if desired There will be no extraneous zeroes placed in the object code file as there would be if the ORG were placed after the program text The label field on the ORG instruction may contain a symbol name in which case the symbol is defined and
24. ands and their uses 2 2 1 Expressions An expression that evaluates to an integer is the most common kind of operand These operands are used for describing the immediate data fields of instructions For example the MVI opcode expects an eight bit value to be specified in the operand field for use as the second byte of the instruction Page 8 MACRO 88 Assembler Manual PolyMorphic Systems 34B6 3E06 MVI A 6 In the above example of an assembly language program line the MVI opcode has two expected operands The first one A is the register specification while the second one 6 is the specifi cation of the value of the immediate byte after the opcode see object code field in listing They are separated by a comma as usual and no space although a space between operands is permitted The next few paragraphs consider the construction of expressions They may be very complex or just a number or a symbol name as shown in the example 2 2 1 1 Numbers A number is a sequence of letters and digits that starts with a digit It can have no imbedded blanks TABs non letters or non digits last character of the number can be a letter indicating the base to be used in interpreting the rest of the number This last character is called the base specifier and is optional If it is left off the number is assumed to be in base 10 decimal Some valid numbers are shown below 123 Value is 123 decimal 123D Same as above with b
25. ase specifier explicitly indicated 200H A hexadecimal number base 16 whose main part is 200 AC6FH A hex number showing the use of the letters A F as digits 10 15 Note that a number must start with a digit so we had to put a zero in front of this one 3770 Octal 377 1101101 Binary 1101101 Hex 6D As shown by the JAC6FH hexadecimal example above a number can always be made to obey the rule that the first character be a digit by simply putting a zero in front The initial digit is important because a number with an initial letter would be taken to be a symbol name 2 2 1 2 Symbols Another kind of expression is a symbol reference which is just a sequence of characters that conforms to the rules for a valid symbol name A symbol name is a sequence of letters digits or the characters and with a first character that Page 9 MACRO 88 Assembler Manual PolyMorphic Systems is not a digit to distinguish the symbol name from a number Symbol names may be any length Here are some valid symbol names HELLO Label Start BiNgO VeryLongSymbolName Hellol24 questionmarks atsigns andmoreatsigns 88 8 8 134 And here are some invalid symbol names lway Starts with a digit go away imbedded blank newStry illegal imbedded character The value of the expression represented by just a single symbol reference is the value that is stored in the symbol table in association with that symbol name If a symbol is no
26. be used to define any kind of symbol except labels that are doubly defined or undefined This means that MACROs or set variables can be stored in a library file and read back in They will maintain their types when passing through the REFS DEFS system Note that the set variables must not be defined some other way before their values are defined by REF or REF will think they have been defined twice REF does not understand the difference between set variables and any other kind of variable and will give a double definition error 2 3 2 14 IDNT The form of the IDNT Identify pseudo op is lt optional label gt IDNT lt expression gt lt expression gt The optional label if present defines a label symbol with a value equal to the current location counter value which is not changed The first expression in the operand field gives the load address La for the output file and the second gives the start address Sa These two values are associated with the directory entries on every file stored on the System 88 but only runnable files use non zero values for them The GO file that the assembler creates will have La and Sa fields as given in the last IDNT pseudo op assembled The load address of a file is the address where it will be placed in memory when it is called to be executed The start address is the address of the first instruction that the system will call by after the file has been loaded in order to begin its execution The
27. codes assembler commands etc Macro references are symbols which the user gives a special meaning The meanings of the label symbols and the operands see 2 1 4 Operand Field are determined by the symbol in the opcode field If the opcode is an instruction mnemonic the label symbol is interpreted as a statement label and can be used elsewhere in the program to refer to the address of the instruction it is attached to The operand field determines the various subparts of the object code instruction such as the address field of a branch instruction If the opcode symbol is a pseudo op or macro reference the meanings of the symbols in the label and operand fields are de termined by the particular opcode symbol used The meaning of each of the fields is defined for each pseudo op elsewhere in this manual Macro symbols can cause the label and operand fields to be inter preted a multitude of ways depending on the user s definition of the meaning of the macro symbol Page 7 MACRO 88 Assembler Manual PolyMorphic Systems Label Opcode field field We use a label symbol HELLO and an opcode symbol NOP HELLO NOP Comment text after the semicolon NOP Comment text can go after the opcode HELLO or after the label Two TABs used here This is comment text There is no label or opcode This is also comment text There is no label or opcode HELLO This statement has only a label but no opcode NOP Only an opcode wit
28. e for execution 3 1 INVOKING THE ASSEMBLER To bring the assembler into memory and have it assemble an assembly language program you type the invocation line as a command to the Exec system giving the file name of the source program and the name you want to assign to the object code program Asmb lt 2 gt SOURCE ASSEMBLY FILE lt 3 gt OBJECT ASSEMBLY FILE The first file specification will be used as the input source text and the second as the object code output file The output file should not already exist or else a message will be printed Output file already exists and the system returns to Exec Likewise the input file must already exist or the system prints Input file does not exist and returns to Exec If the output file is not specified i e only one file is specified then no object code will be gener ated This is not an error 3 2 THE OPTIONS CONVERSATION Upon invocation the assembler is loaded into memory and starts executing The first thing it does is talk to the user about how to do the assembly This is called the options conversation Some yes no questions are asked the user responds by typing Y or N followed by a carriage return When MACRO 88 is satis fied it will begin reading the source file and the drive con taining it will emit an audible clunk as the read write head is loaded brought up to the disk surface The red active light will also come on and the Pass one mes
29. e most significant byte of the l6 bit number is stor d in the higher addressed byte of memory Each element of the operand field of the DW pop is evaluated and its value written to the object code file with the low order byte first The location counter ad vances by two places for each element produced in this way The low byte first format standard for 16 bit numbers in memory used by the 8080 is called by some the byte reversed format because the bytes appear to be backwards in storage when memory byte values are written from left to right ascending addresses Example The statement DW 1234H is stored in ascending order addresses as 34 Hex then 12 Hex Note that the ability of the DB pop to combine a sequence of ASCII character valued elements in the operand list into one long quoted string is not available with the DW pseudo op DB hello there legal DW hello there illegal DW eh 11 o ht re e same as DB Page 25 MACRO 88 Assembler Manual PolyMorphic Systems 2 3 2 9 PRBASE The PRBASE Print Base pseudo op has the following form lt optional label gt PRBASE lt expression gt The numeric printing base of the object code in listings gener ated by MACRO 88 may be set to any base from 2 to 36 by using the PRBASE pseudo op The value of the expression is used as the new base if it is within this range If it is not the error ERROR 0002 Base out of range must be 2 gt 36
30. e oper ators all work for both 2 2 1 6 3 Logical operators All the logical operators work on the 16 bits of their operands separately That is the corresponding bits of each 16 bit num ber operand are operated on and returned in the corresponding bit of the 16 bit result The four operators work according to the following truth table for each bit The table shows for instance that 9 ANDed with produces Binary op B 0 01 11 AND g g 1 OR 0 1 1 XOR 0 1 g Unary op g 1 Page 16 MACRO 88 Assembler Manual PolyMorphic Systems 2 2 2 Symbol Name Operands A few special situations demand that a symbol name be used for an operand an expression is not allowed The REF and DEF pseudo ops are the primary users of the symbol name type of oper and The reason is that the REF and DEF pops are used for referencing and defining the value of a particular symbol in an external symbol table file Thus the use of the general expression type of operand would not be suitable because it yields a numerical value when what we want is just the name of a sym bol For more information on the REF and DEF pops see section 2 3 2 on pseudo opcodes 2 2 3 Expression List Operands Certain pseudo ops DB and TITLE for example will allow an arbitrary number of expressions in the operand field The whole operand field in such cases is considered to contain a single arbitrarily long operand called an expression list Essentially an express
31. embler Manual PolyMorphic Systems After the label a colon may be used to make the program patible with other assemblers that require the colon after labels The colon is ignored completely by MACRO 88 2 1 3 The Opcode Field The opcode field is the next field It always has a space or TAB in front of it either just after the label symbol in the label field or if the label field is blank as the very first character of the statement Thus we say that the opcode field is delimited by a space or TAB the label field is ended and the opcode field begun by one of these characters As many Spaces or TABs as desired may precede the opcode field The op code field may also be blank The opcode field is considered blank if there is no text at all after the label field or if there is only a semicolon followed by comment text Opcodes are the words or vocabulary of assembly language An 4 that is the symbol in the opcode field be either an instruction mnemonic a pseudo opcode also pseudo op or popcode or even pop or a macro reference An instruc tion mnemonic found in the opcode field gets translated into the binary bytes of a machine code instruction which are writ ten to the output file Pseudo opcodes on the other hand normally produce no bytes for the output file but rather serve as control signals to the assembler Pseudo opcodes are known also as assembler directives assembly control
32. ence The pound sign operators used within the body of the macro can be used to indicate where to plug in the parameters for a particular ref erence into the text before it is assembled Pound sign can also give the label that was used on the reference and se 5e 5e e s Page 53 3207 20100 3209 0208 320B 3208 666C6170 320F 23 3214 0102 90002 FFFF 0001 FFFF 2000 0000 3212 4849 3214 4849 MACRO 88 Assembler Manual PolyMorphic Systems the name that was used to reference the macro flap MACRO DW 1 The first parameter in operand field DW 2 second L DS g The label on the reference DB 0 opcode field flap DB uet quoted pound sign DB All the operand field params at once ENDM LAB flap 1 2 1 first parameter in operand field DW 2 The second LABl DS 0 7The label on the reference DB The opcode field flap DB quoted pound sign DB 1 2 All the operand field params at once A recursive macro The first one starts a set variable off at an initial value The second one calls itself and decrements the variable before each call so that eventually it stops calling itself and returns Then each call defines a character string and returns to the previous call C w Se se se Se gt e MACRO Initialization of recursion macro repeat COUNT SET 1 repeat 2 ENDM repeatl MACRO Descender macro IF COUNT gt G
33. er Manual PolyMorphic Systems by the number of places given as its right operand The new bits created at the right are zero Thus SHL acts as a base two exponential function of the form SEL Y gt X 2 Y Of course MACRO 88 has no actual exponential operator as used above but the description is clearer with it The SHR operator acts very much like SHL except that it does not appear to work properly with two s complement as SHL does SHR copies the bits to the right effectively dividing by a power of two However since the created bits at the left are all zeroes negative two s complement numbers are destroyed 2 2 1 6 2 Relational operators Primarily for macro use but useful in many other special cases the relational operators all produce values intended for examin ation by the IF pseudo op This means they produce either a TRUE 1 or a FALSE 0 value regardless of their operands The values of TRUE and FALSE are chosen so that the logical operators will work nicely with them as if they were one bit flags instead of 16 bit integers One can thus write IF X gt Y AND Z 0 OR OKFLAG and the results can be interpreted easily The relational operators are z gt gt lt and lt They are all 16 bit positive integer comparisons positive integer only and the two s complement representations are interchangeable with respect to comparisons of relative values so thes
34. followed by OFFFH Example of use inside a macro MAYBE MACRO IF NOT NULL 1 If there s a parameter 1 DW 1 then assemble it ENDIF di ENDM Thus the invocation MAYBE 5 expands into DW 5 But with a null operand field MAYBE assembles nothing 2 2 1 6 Mathematical expressions It was said above in the discussion on numbers symbols the dollar sign and short strings that each of these things is a Page 12 MACRO 88 Assembler Manual PolyMorphic Systems form of expression These are primary expressions A gener alized expression may be much more complex than a single primary expression because of the ability to combine the primaries into mathematical formulae For example the following is a valid expression 5 HELLO SHR 3 AND X 2 COUNT MOD 256 3 Parentheses can be used to combine operations in any way With out parentheses evaluation proceeds with calculation of the higher precedence parts of the expression first Multiplica tion of two numbers for example would be calculated before the addition of that product to another number even if the addition is written first This is because the multiplication operator has the higher precedence 5 4 6 value 29 not 54 If two succesive operations have the same precedence as do multiplication and division for example then they will be evaluated from left to right The relational operators are an exception they cannot be grouped together as
35. given the value of the new location counter the same value as the value of the expres sion 2 3 2 3 END The END pseudo op has the following form lt optional label gt END It serves to indicate the physical end of the source code to the assembler If the END statement is not found MACRO 88 will ask the operator for a continuation file If the operator does not want a continuation file but has simply forgotten to use the mandatory END statement he may type just a carriage return with no file specification and the result will be just as if there had been an END statement If there are any program statements after the END statement an error results ERROR 1601 Statements found after END 2 3 2 4 Macro system pops The following pseudo opcodes are for controlling the macro pro cessor system of MACRO 88 Since macro programming is an ad vanced process and rather difficult to describe it has been explained separately in Appendix E by means of direct examples The entire appendix is the listing of an assembly program Thus the effects of the macros can be seen as interpreted by MACRO 88 itself Also there are conventions of style and format that are best represented by example Here we give the descriptions of the pops themselves but leave out for example the way the REF DEF REFS and DEFS pops are used to create macro libraries Page 21 MACRO 88 Assembler Manual PolyMorphic Systems 2 3 2 4 1 MACRO The MACRO pseudo o
36. h no spaces before the NOP A space before the opcode no space before the comment HELLO NOP The optional colon after the label This is the exact same line as the top line above 2 1 4 The Operand Field The third field is the operand field It starts after the op code field and is separated from it by a space or TAB It is subdivided by commas into separate parts called operands The symbol in the opcode field determines the meaning of the symbol in the operand field and the number of operands needed The NOP instruction requires no operands at all so the operand field is left empty A branch instruction might require one operand to determine the machine address to go to The DB pseudo op will accept any number of operands A macro reference could accept Say three operands if the first operand were included or none at all if the first operand were not included again it depends on the user s definition of the macro 2 1 5 Comments A comment is a string of text started by a semicolon and ended by the end of the line The semicolon may be used anywhere in any field that is blank The comment field acts like a blank field 2 2 OPERANDS An operand is a modifier for the opcode Each opcode requires different operands and uses them in different ways Some oper ands may be symbol names others integer valued expressions Some contain string expressions some not The next few graphs discuss the different types of oper
37. he 8880 Instructions Here we consider the way the assembler is used to specify any of the 8080 instruction codes opcodes with the desired register or immediate data fields For a complete listing of the instruc tions themselves see Appendix C The 8080 Opcodes Some 8080 instructions accept a second byte after the opcode These two byte instructions are called immediate byte instruc tions because the one byte operand follows the opcode immediately in memory Any valid expression can be used in the operand field to specify the value of such an immediate operand as long as it will fit in one byte If it will not we get ERROR 1203 Value gt 255 truncated to eight bits and the lower eight bits of the value are used Instructions that refer to absolute memory addresses in the 8080 memory space or that put immediate data into a register pair have two bytes following the opcode The two bytes are called a double word an address or just a word The expression in the operand field follows any register pair specification oper and The value of the operand must not be greater than can be expressed in 16 bits or an error results There are only a few ways to get a value that is too big One of them is to specify a number that is too large e g 65536D In this case we get the error ERROR 0D04 Number has value gt 65535 Most 8080 instructions have some form of register specification imbedded in the opcode byte The
38. his Another program can later access the library file with REFS and REF and re create the same symbol definition within its own symbol table Since macros labels register names set vari ables and even opcodes and pseudo opcodes are all defined as symbols they can all be put into library files and accessed later Two examples suggest the usefulness of the system The first is the common situation in which a program is assembled to run in the user address area starting at 3200H The addresses of utility subroutines and data areas within this program are to be shared with a collection of overlays The overlay mechan ism on the System 88 is described in the System Programmer s Guide Basically the overlays all run at 2000H and can only run one at a time Therefore they cannot communicate between each other but act as independent very large swappable sub routines to the main program The library system is used in this example to pass address information from the main program the root to the overlays The root creates the library by using DEFS and DEF The library file is referenced by the over lays when the assembler finds REFS and REF The classic example of this use is in the definition of the System 88 s own root Page 30 MACRO 88 Assembler Manual PolyMorphic Systems which has a library file called SYSTEM SY This library is com monly available to systems programmers The second example of the use of the library
39. in BINGO gt BINGO2 gt BINGO3 which is illegal Operators available for expressions are arranged on the next page in order of increasing precedence the operators nearest the bottom of the table are calculated first Operators with the same precedence are grouped together Page 13 MACRO 88 ASsembler Manual PolyMorphic Systems No of Operator Arguments Function OR 2 Logical bitwise 16 bit OR XOR 2 T 7 exclusive OR AND 2 AND x NOT 1 complement 2 Relational equivalence gt 2 gt greater than lt 2 less than gt 2 greater than or equal to lt 2 less than or equal to 2 inequality 2 16 bit addition 2 subtract two s complement 2 16 bit multiply only low 16 bits of result are available 7 2 16 bit positive divide MOD 2 Modulus remainder of 16 bit division of first argument by second SHL 2 Shift Left First argument shifted left the number of binary places given in second argument SHR 2 Shift Right Similar to SHL _ 1 Unary minus Single argument is negated two s complement Example 1 0FFFF Hex The order of calculation may be fixed by using parentheses around Sub expressions that are to be calculated first No more than five pairs of parentheses can be nested at the deepest level If more are nested a zero value is used for the expression and the message ERROR 0801 Expression nested too deep sorry will be printed If
40. ion list is just a sequence of normal expressions or long strings separated by commas The value of an expression list is a sequence of eight bit quantities When long strings are evaluated the characters between the quotes are used as the eight bit values When expressions are found in the expres sion list the bottom least significant eight bits are used for the value If the value of an expression is too large to fit in eight bits then the error ERROR 1293 Value gt 255 truncated to eight bits results but the rest of the expression list is evaluated as usual The criterion for fitting into eight bits is actually a test of the high order byte of the l6 bit word if it is all zeroes or ones the word will fit Now the distinction between long and short strings can be clarified We have defined a string as a legal component of an expression list However strings of one or two characters are also recognized as expressions Therefore when reading an ex pression list MACRO 88 must decide whether a string it finds is to be considered part of an expression in which case the math ematical operations defined in expressions may be used with it or whether the string is to be considered a long string as defined above It is very useful to have certain strings be part of an expression so that such operations as setting the eighth bit of the ASCII character are available For example DB Hello ther e 80H will a
41. itionals is in macros A macro can be written to produce different results if it is used in differ ent contexts As an example consider a macro that is to assem ble a particular subroutine the first time it is referenced then on successive expansions is to produce CALLs to the sub routine One way to do this is to have the macro first test the value of a certain set variable If the value is 1 say then the subroutine is assembled and the set variable is set to 0 Otherwise a call to the subroutine is assembled and the set variable is left alone Note that some way to set the set vari able to 1 initially is needed 2 3 2 11 1 IF The form of the IF pseudo op is lt optional label gt IF lt expression gt If the value of the expression is zero the statements following the IF pop are skipped until a matching ENDIF is found If the value of the expression is non zero the statements fol lowing the IF are assembled normally Within each IF ENDIF pair there may be another pair The maximum nesting level is 256 Page 27 MACRO 88 Assembler Manual PolyMorphic Systems If an IF pop is found but a matching ENDIF is not found no er ror results But if a lone or unmatched ENDIF is found we get ERROR 1501 ENDIF ELSE ELSEIF without IF 2 3 2 11 2 ENDIF ENDIF ihe matching pseudo op for the IF pseudo op above Its general form is lt optional ignored label gt ENDIF 2 3 2 11 3 ELSE ELSE is an internal delimiter po
42. kage editor system which allows separate assembly of subsections of the program followed by a linking step which connects the object code for the subsections into a single program The System 88 has no such linkage editor and the problems involved in providing one are large such as the necessary complexity of relocation formats and the resultant large volume of dictionary information associated with a re locatable segment for the 8080 Discussion of the design of relocation formats linkage dictionaries and linker loaders is beyond the scope of this manual though some appreciation of the principles involved is important for the advanced assembly language programmer MACRO 88 makes up partially for the lack of a linkage editor system on the System 88 by inclusion of four pseudo ops They constitute a complete library generation and reference mechanism for all kinds of data As such they are actually more useful than a linkage editor They are commonly used not only for passing the addresses of labels from one program to the next but also for defining large libraries of macros and global con stants or system labels The four pops are DEFS DEF REFS and REF The first two are used to create a library file and the second for accessing it They way they work is described below Here we consider how to use them Any symbol in the symbol table can be written into a library file if it is defined within a program DEFS and DEF do t
43. ler Manual PolyMorphic Systems EQUated to l To turn off the HELP printout one would EQUate to 0 2 3 2 11 Conditional assembly The following pseudo ops allow selective skipping of text They can be controlled by the value of an arbitrary expression such as a symbol name or a relational expression BINGO 2QUASI 5 3 Skipped text is read in but completely ignored except for a quick check to see if it contains another conditional pop There are four conditional pops IP ENDIF ELSE and ELSEIF Sections of text are delimited by the IF ENDIF pair with possible ELSEs and ELSEIFs in between The sections can be nested within one an other to an almost arbitrary depth The nested pairs can be skipped over as a unit in other words MACRO 88 knows which ENDIF goes with which IF Note that since even the END statement may be skipped an IF without an ENDIF can sometimes skip all the way to the end of the program and result in the operator getting the familiar prompt No END found Continuation file Conditional assembly is typically used for testing the value of a symbol as when an EQU statement is used at the beginning of a program to control the overall configuration of the assembled program Certain segments of text can be selected for inclusion or omission on the basis of the value of a single symbol so the entire program can be given a massive editing job merely by changing the single EQU statement Another common use of cond
44. n t printed Otherwise a TRUE Value TRUE 9009H will list them Inside a macro it is just as if a LIST pop had been used with the same argument as was the MACLIST Indeeed the LIST pop can be used to change this default for a particular Macro by including it in the macro body The value of the LISTing is saved on entry to macro expansion and is restored to its previous value on exit 1 istxmpl MACRO cB THERE ENDM listxmpl DB THERE MACLIST FALSE listxmpl MACLIST TRUE Now for some examples of the format of the parameters in a macro reference There are two kinds of parameters in the operand field of a macro invocation line 1 A string of characters delimited by a comma right bracket or semicolon The actual string of characters substituted in the macro has blanks stripped from the ends Any of the three special characters can be included within a quoted character string without delimiting the param 2 A bracketed parameter A pair of outside brackets surrounding a string of characters which has a properly matched set of brackets inside or no inside brackets at all Commas and semicolons are also allowed Inside a quoted character string hi brackets need not be nested properly The outside brackets are not passed on into the macro but the spaces inside the brackets are passed on if there is any space Here are some parameter examples e w Sa se e sa
45. n value will be needed as in the MVI in struction 0604 3E25 MVI Ay 3 Load accum with a percent If the string is too long for the instruction a special error message will be printed appropriate to that instruction However if the string is too long for an expression altogether we get ERROR 0203 String is too long for a double word There is a difficulty in expressing the single quote sign itself within a string since it is used as the delimiter for the end of the string If it is used in the middle of a string the assembler would normally think it has found the end of the string To circumvent this problem a special facility has been added If the end of a string is found but another string follows im mediately then the two strings are considered as one string with a single quote mark in between Examples don t know value is I don t know da value is just single quote value is two single quotes ds value is null string Note that everything we have said about expression lists in short strings also applies to long strings 2 2 1 5 Functions Functions are normally used in macro programming to do things to parameters passed to a macro They have 16 bit values just like any other expression primary but operate in some special way on the things between the two following brackets The brackets delimit the boundaries of the text looked at by a function The left bracket immediately f
46. name operands see Section 2 2 2 Symbol Name Operands This pop is used as an external reference system for assembly time definition of symbols created and stored in a library file by a previously assembled program The symbol whose name is given in the operand field is created in the program currently being assembled Its value and type are given by its entry in the library file the value and type are unrestricted except that they must make sense as symbol table elements In other words any symbol put into the library file by a previous use of DEFS and DEF came out of the symbol table from a previous Page 31 MACRO 88 Assembler Manual PolyMorphic Systems assembly and thus is guaranteed to make sense as a symbol table element Library files created by other means than using the DEFS and DEF in an assembly program are not checked for validity and can produce anomalous results If the symbol being defined through a REF is defined elsewhere in the program then we get ERROR 1701 Double definition by REF If there is no symbol with the given name in the library file then the symbol is left undefined after the REF and we get the error ERROR 1704 Symbol not found in REF file 2 3 2 13 3 DEFS The form of the DEFS Definition File Specify pop is lt optional ignored label gt lt file name operand gt The function of DEFS is to open an output file for subsequent output definitions of external symbols via the
47. nition of unary minus Any number of unary minuses may precede any kind of valid pri mary expression to change its sign Each occurrence of a minus sign negates the value once Multiplication is a positive multiplication of the two 16 operands to form a l6 bit product I the result is larger than 65535 the bottom 16 bits are returned as the product This allows numbers which are to be regarded as negative two s com plement numbers to be multiplied and to have their signs effect ively exclusive ORed In other words 1 1 1 1 1 1 1 1 1 and 1 1 1 For positive numbers non two s complement however a result larger than 65535 will appear to be within range using this scheme It is the programmer s responsibility to insure that the result can never exceed the 16 bit representability limit or to insure that the overflow can have no dangerous effects Division and modulus X MOD Y are similar to multiplication in the way they handle two s complement versus positive only rep resentations They differ in that they produce ERROR 4101 Division by zero when their second operands are zero The modulus operator re turns the remainder of the division of its left operand by its right Thus the full 32 bit result of a 16 bit by 16 bit divi Sion is available by performing the division twice once with the and once with the MOD The SHL operator copies the bits of its left operand to the left Page 15 MACRO 88 Assembl
48. ollowing the function name is actually part of the function name so no spaces should be used in between 2 2 1 5 1 LEN The LEN function evaluates the contents of its bracketed text area as if they were an expression list to be submitted to the DB pop Instead of assembling the data bytes however LEN Page 11 MACRO 88 Assembler Manual PolyMorphic Systems merely counts them and returns their total number In other words if the same string given to LEN is substituted into a DB pop in the operand field the outputted object code will oc cupy the number of bytes in memory that LEN returns as its value As an example consider the following DB LEN Hi there 2 Hi there CR LF This statement will assemble first a byte with value 11 decimal then 9 bytes of ASCII character information followed by 2 sym bolically defined constants 2 2 1 5 2 NULL In a macro it is possible to pass a parameter which contains no characters at all This happens when a position in the oper and field of the macro invocation is left empty The parameter is then considered non existent or null The NULL function allows a macro to take appropriate action when an optional para meter has been omitted It returns a logical value of TRUE 1 or QFFFF hex when there is a null parameter between the brackets and FALSE 0 when any number of valid parameters can be found there Example DW NULL I am not null NULL This assembles 0000H
49. p for IF ENDIF pairs By itself the ELSE statement is illegal and gets the 1501 error shown above The form is lt optional ignored label gt ELSE The ELSE pop acts to switch from skipping to non skipping and non skipping to skipping mode between an IF and an ENDIF Two ELSEs in a row inside a single IF ENDIF pair result in the second one being ignored Normally ELSE is used in a structure with the other conditional pops as follows IF lt gt lt subsection A gt ELSE lt subsection B gt ENDIF The effect is to assemble subsection A if lt expr gt is non zero or subsection B if it is zero One and only one of the sub sections will assemble Any number of IF ENDIF pairs and hence of the above structure can be imbedded within subsections A or B 2 3 2 11 4 ELSEIF ELSEIF is exactly the same as ELSE except that instead of just reversing the skip condition skip no skip no skip skip it tests the value of the expression in its operand field just as IF does The form then is lt optional ignored label gt ELSEIF lt expr gt Page 28 88 Assembler Manual PolyMorphic Systems A sequence of ELSEIFs between IF and ENDIF do not result in the last ones being ignored as results from a sequence of ELSEs Instead the ELSEIFs are evaluated until one of them or the original IF succeeds doesn t skip After one has succeeded the other ELSEIFs or ELSES are skipped up to the ENDIF nor mal sequence of
50. p has the form lt macro name gt MACRO The macro name label is put into the symbol table as a macro symbol and all statements in the text following the MACRO pop up to but not including the ENDM pop are stored in the symbol table as the value of the symbol The sequence of statements between the MACRO and the ENDM pops is called the macro def inition or prototype None of the statements are assembled normally they are just read in and checked to see if one is the ENDM pop Errors in the statements of the definition will not be detected they are just scanned and read Example BINGO MACRO Begin the definition of BINGO DB HT This statement is the prototype You could have several instructions here ENDM This terminates the definition intervening program BINGO Reference the MACRO After the definition in the text there may be any number of macro references which are statements that use the macro symbol name as if it were an opcode The result of the macro reference is to substitute the prototype into the text as if it had been included in the original source The example above would assemble the DB statement is the prototype after any reference to the macro As with any other symbol name macro names must be unique No opcode pseudo opcode label or set variable may have the same name as any other If a name in use is used on something else the double definition error
51. phic Systems p Pee dede e jet ehe de he hee he eje de fe e e He He fee e de He de e ee e e ht e dede e eee hee 2 MACRO TESTER DEMONSTRATOR This is a demonstration of the use of the macro facility of the MACRO 88 assembler for the PolyMorphic Systems System 88 microcomputer Illustrated are 1 Basic macro definition format 4 2 Referencing formal arguments within body of macro text z 3 Basic technique of recursion and macro nesting 4 Using a macro to define a macro 5 Listing control of macro expansions s 6 Format for actual arguments params using nested brackets strings 3 7 The LEN and NULL functions BES HORI IOI ISCO IIIT IIIS IIR eel 3200 ORG 3200H 3200 IDNT 32008 3200H FFFP TRUE SET 1 0000 FALSE SET g 000 CR EQU DH A simple text substitution macro The invocation line is the first line the termination line is the one with the ENDM on it and the body is the collection of lines in between Label field of the invocation line is the name of the macro lem EE izzarre MACRO DB WOW1 1 0 ENDM A reference to the macro results in assembly of the body of the macro as if it were in the input file X e s bizzarre 3200 574F5721 DB WOW111 g 3294 212100 Parameters are passed into a macro in the operand field of the refer
52. r macro entries The macro we use accepts just the name typecode and value g Popcode key generator 1 2 8 Name Typecode Value Subtype 2 LEN 1 7 LEN 1 1 OPCTYPE 3 NOT NULL 4 4 0 2 POPTYPE POPGEN 1 POPGEN LEN 1 6 LEN 1 1 POPTYPE 1CODE Pop type Page 58 0000 FFFF 0001 0001 3271 3273 3277 3278 0004 0000 FFFF 327D 327 3283 3284 3288 328C 3290 3294 3298 FFFF 3299 329B gcgg 06505242 41534502 0100 1088 03776 77 88 204D5649 28412C27 21270024 43414C4C 20574830 2D AJA 03474554 MACRO BB Assembler Manual POPGEN ELSEIF DW DB DB ENDIF ENDM symel IF DW DB DW IF DB ELSE DB ENDIF ELSEIF SET PRBASECODE POPGEN wowCODE ELSEIF DB DB PolyMorphic Systems 2 MACTYPE LEN 1 LEN 3 4 LEN 1 1 MACTYPE 3 PRBASE POPTYPE POPTYPE OPCTYPE LEN PRBASE 7 LEN PRBASE PRBASE OPCTYPE NOT NULL g POPTYPE POPTYPE Pop type POPGEN 1 EQU POPGEN LEN PRBASE 6 LEN PRBASE PRBASE POPTYPE PRBASECODE POPTYPE MACTYPE LEN PRBASE LEN 4 LEN PRBASE PRBASE MACTYPE wow MACTYPE MVI A I CR CALL WH9 CR MACTYPE OPCIYPE LEN wow 7 LEN wow wow OPCTYPE MVI A CR CALL WHO CR NOT NULL MACTYPE POPTYPE Pop type POPGEN 1 POPGEN LEN wow 6 LEN wow wow FOPTYPE wowCODE
53. rams very small optimized object code or some series of machine operations that can only result from a very specific sequence of instruc tions In fact the whole purpose of an assembler is to produce a known sequence of instructions in memory Assembly languages including MACRO 88 also have special facilities to overcome some of the more painful inconveniences of writing a program an instruction at a time These facilities Page 2 MACRO 88 Assembler Manual PolyMorphic Systems include labels macros assembly time mathematics and several other things all of which will be discussed later O 1 2 FILES USED BY THE ASSEMBLER For now we will concern ourselves with the problem of handling the text the assembly language program that you write and the object code the machine language translation that the as sembler produces of the assembly program System 88 has special abilities for handling object code programs as files which it automatically identifies by putting the exten sion GO on their disk file names Files containing the text of a program the human readable assembly language form of the program are stored with TX extensions You create and correct them by using the system text editor The text file for an assembly language program might be only a few sectors in length or so long it has to reside on more than one disk It can be too large to fit in the computer s main memory all at once so the assembler mus
54. re plain text rather than single character codes as used by most assemblers A typical error message in a listing might look like ERROR 491H String too long sorry Each statement in an assembly listing can generate up to two error messages The first one may be a non fatal error but the second is fatal A non fatal error does not stop the trans lator from working on the rest of the input text on that line while a fatal error results in the translator giving up completely and starting on the next input statement The user does not need to be concerned with the two types of error as there will almost always be only one error in one statement of the program It may be important to know however that even if a statement has many things wrong with it only two errors will cause messages to appear in the printout 3 3 5 The Symbol Table Printout The symbol table printout is a table that shows the names of the symbols found in the program and the values they were as signed There are actually four tables that may appear in the printout but usually most of them contain no elements and so they are not printed The four tables list the undefined vari ables the doubly defined variables the set variables and the properly defined labels Usually the last table the label table is the only one that prints out It may be anywhere from one or two elements to several hundred and can require several pages of printout Elements
55. results ERROR 1302 Doubly defined symbol or ERROR 1301 Cannot redefine system symbol MACRO ENDM pairs can be nested to any depth This allows a macro to define a macro A MACRO ENDM pair contains the prototype for a macro so if there is another MACRO ENDM pair within that pair the inside pair s will be part of the prototype Then when the prototype is evaluated by doing a reference to the symbol Page 22 MACRO 88 Assembler Manual PolyMorphic Systems name for the containing MACRO ENDM pair the inside MACRO pop will be seen at the top level and will define another macro This is shown in Appendix E 2 3 2 4 2 ENDM ENDM has the form lt ignored label gt ENDM lt ignored stuff gt It terminates a macro definition as discussed above If used without a corresponding MACRO pop the error ERROR 0 01 ENDM without previous MACRO results Any number of ENDMs may occur with no intervening MACROs in practice because the MACRO ENDM pairs may be nested to any depth desired The 0F01 error occurs when ENDM is used at the top level in other words when there are already as many preceding ENDMs as MACROs The converse problem occurs when there are too few ENDMs as com pared with MACROS in a program However there is no way for MACRO 88 to know that this was not intended because the pro grammer may have the rest of his macro in another file Thus MACRO 88 will sometimes ask No END found
56. rints the listing The first pass then is a quick scan of the program during which the actual meanings of Page 3 MACRO 88 Assembler Manual PolyMorphic Systems the statements are largely ignored For the second pass the input file is rewound and the program re read this time the assembler puts in the values of the symbols and generates the object code The assembler handles the two passes over the text automatically You don t need to rewind the input file or do anything yourself between the two passes Once the assembler knows what file is to be assembled it can proceed on its own until it finishes 1 3 2 Using Multiple Source Files The disk does relieve you of most of the hard work involved in an assembly but there are still limits primarily those imposed by the size of the disk storage A very large program can be too large for one disk so you must somehow change disks in the middle of assembly There is a special facility in MACRO 88 for assembling programs that are distributed among multiple files or even multiple disks To handle multiple input files the assembler asks you for the name of a continuation file after it finishes reading a file But there still must be a way to have the assembler automatically rewind and go into pass two if the entire source text is in one file Here is how these two requirements are both fulfilled at once All assembly language programs to be translated by the MACRO 88 must end with an END
57. sage printed Below is the display on the video screen for an example conver sation and complete assembly Page 36 MACRO 88 Assembler Manual PolyMorphic Systems Printer Terminet SAsmb lt 2 gt RAKE7 lt 3 gt RAKE MACRO 88 Version vvv mo day yr Hardcopy default is video display Y or N Y Full listing else errors only Y or N Symbol table printout Y or N Y Pass one Pass two listing is being printed Error total 0 Return to Exec In this conversation the user first asks the printer configura tion program to install a printer driver program called Term inet Once the driver is installed the system understands how to talk to a particular kind of printer MACRO 88 sends characters down the printer wormhole which is its means of communication with the currently installed printer driver Thus MACRO 88 does not know what is being done with the listing it produces and the user has complete control over the fate of the listing text In the example after the MACRO 88 invocation the user types Y to the first question This tells MACRO 88 to send the listing to the wormhole N answer would send the listing to the video screen and the wormhole would not have to be set up for the printer driver Printer Terminet The video display mode prints the listing on the screen stopping every 14 lines printing a period and waiting for the user to type a character before continuing the listing The next ques
58. se instructions may be one two or three bytes long owing to immediate fields as described above Register specifications are NOT generalized expressions as used for any of the immediate data operands Instead a register spec can be any of the following designations Page 19 MACRO 88 Assembler Manual PolyMorphic Systems A B C D E H L PSW SP Here are some examples of operand usage in instructions LXI H Loads H and L regs with 0 CALL AGAIN Subroutine call to AGAIN JMP DOWN 7 GOTO DOWN AGAIN SHLD ROCK Put HL into ROCK and ROCK 1 LHLD STONE Get HL from STONE and STONE 1 LXI SP TOS Put TOS address into 8080 Stack pointer JM ITSMINUS Jump if accum minus STA SMALLROCK Put accum value in SMALLROCK LDA SMALLSTONE Get accum value The label field of a statement that has an instruction mnemonic in the opcode field an instruction statement is optional If the label field is used the symbol name it contains is entered into the symbol table as a label symbol with the value given by the address of the first byte of the instruction Thus the JMP in the following code will take the machine to the CALL instruc tion rather than to the IN instruction JMP LAB1 Jump to it LAB1 CALL SUBR1 Do the routine IN 8 2 3 2 Pseudo Ops in MACRO 88 2 3 2 1 EQU The EQU Equate pop has the form lt symbol name gt EQU lt expression gt A new symbol is created in the symbol table and given the value that the expression ev
59. ssemble Hello there with the eighth bit of the e high The problem is resolved in MACRO 88 by defining a one character Page 17 MACRO 88 Assembler Manual PolyMorphic Systems string to be part of an expression a short string and any longer string to be self contained a long string This allows math on single characters as shown above Expressions are allowed to have two character strings as oper ands because they can be considered 16 bit quantities Then why was the boundary of short versus long chosen at one rather than two characters The reason is that a two character string would evaluate differently when considered an expression than when considered a string This is because the first character of a two character string in an expression would be put in the higher order byte of the expression value and would be thrown away as well as generate an error One character strings can be con Sidered either expressions or strings with no change in the results MACRO 88 looks for strings while scanning an expres sion list When it finds one that has only one character in it it backs up and assembles it as an expression Here are some examples of expression lists WA Ao tas 1 UP Ri 7 ati tg at AA 331 4CR The easy way CR 1 2 3 4 simple expression list 3 BINGO AND FFH TWO combined expression and string This is line CR The common NUL terminator NULL 1 LEN HELLO HELLO LABELSYM
60. state ment is read The output object code file gets a string of zeroes as long as the skip distance The optional label will define a symbol at the location counter address that is in effect before the skipping takes place Thus the label gets the address of the first byte in the storage area The DS pseudo op works somewhat differently in the special case when no object code has been written to the output file at the Page 24 MACRO 88 Assembler Manual PolyMorphic Systems point of use In this case instead of outputting the string of zeroes it just moves the location counter This way the output file is smaller because it does not have redundant zeroes in front 2 3 2 7 DB The form of the DB Define Byte pseudo op is lt optional label gt DB lt expression list gt The value of the expression list is a string of bytes written directly to the object code file See Section 2 2 3 on the expression list type of operand for more information If the optional label is used the label symbol defined will have the address of the first byte in the contiguous string of bytes defined 2 3 2 8 DW The form of the DW Define Word pseudo op is lt optional label gt DW lt expression list gt The DW pop works very similarly to the DB pop but the expression list is used as a string of double words rather than bytes to be placed directly in memory A double word is a sequence of two bytes in memory that represents a 16 bit integer Th
61. system is build ing macro libraries In this case the symbols saved in the library are all macro definitions The program which builds the macro library generates no object text at all it only builds the library file Later unwritten programs will use the library even after the defining program is retired to the archives Here is where the MACRO 88 library system beats the linkage editor Examples of actual macro library definition and reference are given in Appendix E 2 3 2 13 1 REFS The form for the REFS Reference File Specify pseudo op is lt optional ignored label gt REFS lt file name operand gt For more information on the structure of the file name operand see the System 88 User s Manual or section 2 2 4 of this manual on file name operands The action of REFS is to open a special kind of input file called a library file This kind of file is usually created by using the DEFS and DEF pseudo ops described later Once a REFS has been seen and accepted MACRO 88 the REF pseudo op may be used If there is no REFS then the use of REF will generate 4 ERROR 1702 REF without previous REFS If the input file is not found or is specified improperly assembly stops and the video display gives the System 88 error message corresponding to the error 2 3 2 13 2 REP The form of the REF Reference pseudo op is optional ignored label REF lt symbol name operand gt For more information on valid symbol
62. t resort to devious means to translate the program without being able to examine more than a small section of it at a time Note that the text for a program may be very long but the object code will usually be far shorter 1 3 THE ASSEMBLY PROCESS 3 During assembly of a program the assembler reads the text ver sion of the program from the disk and writes the object code version of the program onto a disk not necessarily the same disk At the same time the assembler can generate a listing which is a printout of the statements the assembler read and the numerical values of the object code it generated for each state ment all arranged in an easy to read form 1 3 1 The Two Passes The text of the program is actually read twice once in Pass one and then again in Pass two The reason it takes two pas ses is this Before the assembler can actually assemble the assembly language program translate it into object code it has to build up a symbol table The symbol table is a list of the symbols used in the assembly program with the associ ated values of each of these symbols stored beside the symbol The problem is that frequently a symbol s value is not defined in a program until some time after it is first used or refer enced Thus during the first pass the assembler collects all the definitions of the labels throughout the program so as to use them on the second pass when it actually writes out the object code and p
63. t SOURCE 2 TX User replaces disk and gives next file name Pass two Continuation file had an END Re specify original input file please lt 2 gt SOURCE 1 TX User replaces first disk and types first file name No END found Continuation file lt 2 gt SOURCE2 TX User replaces disk again but types wrong name That file does not exist No END found Continuation file lt 2 gt SOURCE 2 TX Now assembly continues Error total Hurray s back to Exec 3 3 LISTING FORMATS A listing is the text printed out by the assembler while it is translating the user s program In the next few paragraphs we will discuss the things that are printed by MACRO 88 in the listing 3 3 1 Source Code Listing Each statement or line of the input source text is formatted or shaped by the assembler into a source listing line which is of the original line along with the assembler s interpre tation of it in terms of the object code that was produced by it The source listing line consists of the address field the ob ject code field and the source text field The address field Page 38 88 Assembler Manual PolyMorphic Systems is the print area for the address assigned to the instruction in the assembly statement The object code field shows the actual data that was generated to go in the printed address The source text field is just the original text line itself with some of the right end of i
64. t cut off usually only comments are lost so that it will fit on the line Address Object code Source text field field field 388C 4 CPI 4 If base lt 4 then 388 D29938 JNC PUTLS8 next time through 3891 CDD245 PUTLS3 CALL PUTLINE Write out the line 3 3 2 Effect of the PRBASE Pseudo Op The PRBASE pop described in section 2 3 2 10 changes the value of a variable within the assembler PTBASE that indicates the current numeric base being used for all printed values except error counts Its effect on the assembly source listing is to change the address field and object code field printouts None of the source text field is changed If the base is less than 4 then an address takes up so much space in the object code field that there is not enough left for even one byte of object code In this case the object code is printed on the following lines as shown in this example using base 2 1011000101011110 CALL COLLECT After 8 00 it s 11001101 00010140 10001001 1011000101100001 ANI OF8H cheaper 1110901180 11111000 When PTBASE is large enough that numbers fit two on a line they are packed together without any space in between This is easy to understand with hexadecimal but is a little strange perhaps in octal 067303 346201 ANI LITTLEORPHAN especially since the address field is printed in packed octal rather than the preferred split octal The PTBASE in effect when the assembly also effec
65. t defined anywhere in a program and yet is referred to in an expression a value of zero is used and an error message is printed ERROR 1101 Undefined symbol reference If a symbol has been defined twice in one program the value of the symbol is undefined The assembler actually uses the first value assigned to the symbol for the value in the expression and the message ERROR 1192 Doubly defined symbol is printed 2 2 1 3 Dollar Sign The dollar sign is a valid expression whose value is the load address of the instruction being assembled at the point where the dollar sign is used Thus if we assemble a JMP instruction the result will be an opcode for a jump with an immediate address that is the same as the address of the jump instruction itself When executed the computer will loop for ever The dollar sign is valid wherever an expression is valid 2 2 1 4 Short strings An expression may have a value which is an ASCII character con Stant In this case the character that is to be used can be Page 19 MACRO 88 Assembler Manual PolyMorphic Systems expressed in single quotes or apostrophes 41 ry 6C Hex HI 4849 Hex Note H is most significant BINGO 4249 Hex BI used rest lost Since the value of an expression is limited to 16 bits there cannot be more than two characters in a short string Usually a short string is used where only the least significant eight bits of the expressio
66. tion determines whether each line of the original text will be printed in the listing or only the lines that gener ate errors The errors only mode will omit correct source text lines but will print all other output lines such as the symbol table printout and error summary The last question establishes whether the symbol table listing will occur Any of the questions can be answered no with N n or nothing at all and can be answered yes with Y or y All responses are followed by a carriage return After the last question the user sees Pass one Page 37 MACRO 88 Assembler Manual PolyMorphic Systems so he or she sits back and waits for Pass two when the listing starts Pass one takes about one minute for each 1000 3000 lines depending on the nature of the program text Pass two takes somewhat longer but is usually limited by the speed of the printer anyway When printing is complete the error total is displayed as a check for the user Finally the output file is closed the drives clunk back and forth for a while and the system returns to Exec and gives the prompt If the assembler does not find an END statement it asks the user to specify a continuation file This makes it possible to have the source text for a program in many different files or even on separate disks After the options conversation the Screen might look like this Pass one Normal start of assembly No END found Continuation file lt 2 g
67. ts in assembly language all have the same basic structure Each program line is a made up of several fields sub parts oF the line of text used for certain dedicated functions Thus when you read a line of assembly language program the item you encounter first the one over on the left is likely to be a label since the label field is the first field It s important to note that the field is not the same as the thing that s in the field the label field may not have anything in it A field is like a box with a tag on it anything inside the label box is a label but the label box can be empty The three main fields are the label opcode and operand fields 2 1 2 The Label Field A label is one of several different kinds of symbols used in assembly language Symbols are created in a very strict way from letters digits and special characters exact specifica tions for symbols are given in a later section The symbol used in the label field is called a label symbol to distinguish it from symbols used in other fields The label field is the first field on the line can contain a label or it can be blank The label field is considered blank if there is no symbol at the left end of the statement line If there are any spaces or TABs before the first symbol or in fact if there are ANY characters that are not allowed as part of a symbol at the front of the statement the label field is considered blank Page 6 MACRO 88 Ass
68. ts the printout of a symbol table listing if one is requested The normal base 16 hexadecimal printout fits conveniently on the 64 character video display line but is too long for lower bases This is normally no problem with hardcopy since most printers have at least 80 columns The symbol table listing displays eleven characters of the symbol name followed by the value and a space Thus the printout for hex is 11 4 1 characters or 16 characters Page 39 MACRO 88 Assembler Manual PolyMorphic Systems per element We print a fixed four elements per line For base two then the line is 11 16 1 characters per element 4 ele ments or 112 characters A possible way to avoid problems with this expansion is to use a PRBASE 16 just before the END statement 3 3 3 Full and Errors Only Listings In the options conversation the user is asked whether he wants a full or errors only listing In a full listing all the lines in the source program are printed whereas in an errors only listing only the lines that contain errors are printed The errors only listing is a handy way to check a program for validity or to find the errors in it without having to wait for the whole printout or having to inspect all the lines of a list ing for error messages Each error line printed in an errors only listing is followed by the usual error message with the English text summary of the problem 3 3 4 Error Message Format Error messages in MACRO 88 a
69. ty Report available from PolyMorphic Systems One particularly convenient feature of the System 88 is the ability of the user to alter message texts by means of the Enedit error message editor Emedit is described in the System Library volume System 88 System Programmer s Guide It can be used to change any of the messages in tne following sum mary table These are the error messages printed on the listing for errors generated by statements in the source text None of the operator conversation messages are available in the Amsg OV overlay Page 42 MACRO 88 Assembler Manual PolyMorphic ERROR MESSAGE SUMMARY Error number Message text 0191 Division by zero 0201 Expression has unbalanced parenthesis 8283 String is too long for a double word 0204 Invalid operand I can t figure it out 2301 Opcode field symbol undefined as a macro 0302 OPCODE FIELD NON OPCODE FOUND 0343 Opcode field is not valid symbol name 0304 11 BAD OPCODE SUBTYPE 0345 Opcode field has symbol of illegal type 0401 String too long Sorry g501 Expression too complex Sorry 0701 Number has bad base specifier 8702 NUMBER HAS NON NUMERIC FIRST CHAR 0801 Expression nested too deep Sorry gB01 Missing comma 0802 Register pair specification value illegal 9803 Register specification value illegal BJA B D register specification value illegal 0 01 Symbol table full Sorry 0 02 11 NON IDENTIFIER PASSED SYM FUNCTION
70. zero as a code message Page 44 MACRO 88 Assembler Manual PolyMorphic Systems Page 45 MACRO 88 Assembler Manual PolyMorphic Systems Appendix C 8080 OPCODES REFERENCE LIST FUNCTIONAL LISTING OF THE 8080 INSTRUCTION SET MOVE ACCUMULATOR 40 MOV B B 60 MOV H B 80 ADD B Ag ANA B 41 MOV B C 61 MOV H C 81 ADD C Al ANA C 42 MOV B D 62 MOV H D 82 ADD D 2 ANA D 43 MOV B E 63 MOV H E 83 ADD E ANA E 44 MOV B H 64 MOV H H 84 ADD H A4 ANA H 45 MOV B L 65 MOV H L 85 ADD L 5 ANA L 46 MOV B M 66 MOV H M 86 ADD M A6 ANA M 47 MOV B A 67 MOV H A 87 ADD A A7 ANA A 48 MOV C B 68 MOV L B 88 ADC B XRA B 49 MOV C C 69 MOV L C 89 ADC C A9 C 4A MOV C D 6A MOV L D 8A ADC D AA XRA D 4B MOV 6B MOV L E 8B ADC E E 4C MOV C H 6C MOV L H 8C ADC H AC XRA H 4D MOV C L 6D MOV L L 8D ADC L AD XRA L 4E MOV C M 6E MOV L M 8E ADC M AE XRA M 4F MOV 6F MOV L A 8F ADC A AF A 56 MOV D B 70 MOV 90 SUB B B ORA B 51 MOV D C 71 MOV M C 91 SUB C Bl ORA C 52 MOV D D 72 MOV M D 92 SUB D B2 ORA D 53 MOV D E 73 MOV M E 93 SUB E B3 ORA E 54 MOV D H 74 MOV M H 94 SUB H B4 ORA H 55 MOV D L 75 MOV M L 95 SUB L B5 ORA L 2 MOV D M 96 SUB M B6 ORA M 57 MOV D A 77 MOV M A 97 SUB A 7 ORA A 58 MOV 78 MOV 98 SBB B CMP B 59 MOV E C 79 MOV A C 99 SBB C B9 C 5A MOV E D 7A MOV A D 9A SBB D BA CMP D 5B MOV E E 7B MOV A E 9B SBB E BB CMP E 5C MOV E H 7C MOV A H 9C SBB H BC CMP H 5D MOV E L 7D MOV

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