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Bally Service Manual

1. HEAT SINK e CASSETTE AD z ZD 78 40 C22 44 D Ca 419 Alt 47 Kb x x N ob d a D Ki RR DIS RIER NNN ry 472 al 3 26 aidia jd j RB SSS Nis HOME VIDEO LOGIC SCHEMATIC ka SH KEEN HALT BYSACK E273 NMI 8038 26 Gs 45 GB EXPAND CONNECTOR VERT DR E HOR Bally Service Manual Version 1 0 Released Nov 10 2000 This document has been scanned and converted to PDF format courtesy of the Bally Alley newsletter For other reprints and more information visit http www ballyalley com Corrections Suggestions Email Adam Trionfo at ballyalley hotmail com MANUFACTURED BY BALLY MANUFACTURING e CORPORATION CONSUMER PRODUCTS DIVISION 10750 W GRAND AVE FRANKLIN IL 60131 CABLE ADDRESS MIDCO e TELEX NO 72 1596
2. 678 Printed in U S A 620 303
3. In this installation it will be necessary for you to purchase 75 ohm to 300 ohm transformer available from you local dealer or any television service organiza tion 1 Remove Coaxial Cable Connector from its socket on the back of the TV set then connect it to the socket of the transformer Avoid bend ing of center wire in cable 2 Connect the 300 ohm flat twin lead wire coming from the end of the transformer to the terminals marked Connect to Antenna on the adapter switch 3 Connect the short length of 300 ohm antenna wire coming from the side of the adapter switch to the VHF terminals of your TV Addi tional TV adapter switches may be purchased at your local dealer so you may install one on each television set in your home COAXIAL GAME CORD COAXIAL GAME CORD ANTENNA SWITCH BOX TV ADAPTER TO ANTENNA SWITCH ANTENNA SWITCH BOX TERMINALS ON CONNECT TV RECEIVER TO TV ome CONNECTION TO VU S YOUR TV RECEIVER TERMINALS ON TV RECEIVER CONNECT TWIN LEAD TO TV VHF ANTENNA WIRE ANTENNA WIRE 75 OHM 300 0HM TERMINAL TRANSFORMER UNUSED FIGURE 2 FIGURE 3 300 OHM TWIN LEAD INPUT 75 OHM COAXIAL CABLE INPUT Il Carefully unroll the Coaxial Cable from the Arcade console and plug it into the TV adapter switch receptacle marked Game Plug the power supply cord into a 120 volt AC out
4. 00003 0191 6 32X screw for cassette conn 0017 00101 0774 6 32 nuts for above 0017 00103 0060 Line Filter Assy A620 00034 0000 Power Supply Conn 4 pin 3000 16326 0400 21 FINAL CABINET PARTS LIST Bally Part Number 0017 00003 0190 0017 00007 0135 0017 00101 0067 0017 00101 0074 0017 00101 0776 0017 00042 0170 0620 00011 0000 0620 00111 0000 0620 00247 0000 0620 00302 0000 0620 00907 0200 0620 00907 0300 0620 00907 0400 0620 00910 0000 0620 00912 0000 0620 00913 0000 0620 00914 0000 0620 00915 0000 0620 00916 0000 0620 00919 0000 0620 00920 0000 0620 00921 0000 0620 00923 0000 0620 00939 0000 A620 00003 0100 A620 00004 0000 A620 00933 0800 Description R F modulator U Clip 8 unit X Alunit Da X 1 4 unit 9 X Slunit Nylon Spacer 4 unit Consol Packaging Mat Keyboard Overlay Ejector Spring Owner s Manual Knob 2 Knob 3 Knob 4 R F Coax Cable R F Adaptor Cabinet Top Cabinet Base Top Cover Tape Lid Keyboard Housing Ejector Button Ejector Reset Button Name Plate R F Shield Top Control Handle Power Supply Assembly Mother Board NOTES 23 E 232 p i u 77 1111 KEY BOARD Y ER y e 2 72 1 ul 11201 277 2 peee 4 rmn E FEID Ak a Uu 23 Her j cet ace D re 8 gh 88 1220 AF MUONEATOR oA Pee EE r 2222
5. generated MUSIC PROCESSOR The music processor can be divided into two sections The first section generates the Master Oscillator Frequency and the second section uses the Master Oscillator Frequency to generate tone frequencies and the analog audio output The contents of all registers in the Music Processor are set by output in structions from the Z 80 Master Oscillator Frequency is a square wave whose frequency is determined by the 8 binary inputs to the Master Oscillator This 8 bit word is the sum of the 12 contents the Master Oscillator Register and the output the MUX The MUX is controlled by MUX REG If MUX REG contains 0 then data from the Vibrato System will be fed through the MUX The two bits from the Vibrato Frequency Register determine the fre quency of the square wave output of the Low Frequency Oscillator The 6 bit word at the output of the AND gates oscillates between 0 and the contents of the Vibrato Register The frequency of oscillation is determined by the contents of the Vibrato Frequency Register The 6 bit word along with two ground bits are fed through the MUX to the Adder This causes the Master Oscillator Frequency to be modulated between two values thus giving a vibrato effect If MUX REG contains 1 then data from the Noise System will be fed through the MUX The 8 bit word from the Noise Volume Register determines which bits from the Noise Generator will be present at the output of the AND g
6. two rows of keys control the intensity level of a color When changing to any color or intensity of color the key must be held down until you reach the desired result Videocades The Bally Arcade not only has four games built in it has virtually hundred of game possibilities With optional Videocade cassettes one can have a veritable library of games and educational tools Videocade cassettes are now available in a variety of programs that include an Educational Series a Sports Series an Action Skill Series and a Strategy Series And more are on the way CONNECTION TO TV RECEIVER Included with the Bally Arcade is a TV adapter switch This switch allows selection of either the Bally Arcade or regular TV viewing Simply move the slide Switch to the mode desired Game position for Bally Arcade or position for television Adapter Switch Connections A Connection to sets having 300 ohm antenna system with screw terminals See figure 2 1 Locate the VHF antenna terminal on the back of your television set Remove the existing wires connected to the VHF terminals Attach these wires to the terminals marked Connect to Antenna at the base of the adapter switch 2 Connect the short length of antenna wires coming from the side of the adapter switch to the VHF terminals of your TV set B Connection to sets having 75 ohm antenna system employing Round Coaxial Cable and Cylindrical Connector See figure 3 Note
7. 120 ADAPTER FIGURE 5 MOVE TO POSITION 4 CHANNEL 3 POSITION HAND CONTROLS Each hand control is numbered on the top of its knob It is important to insert each control into its corresponding numbered location on the back of your Ar cade See figure 4 The detailed action controlled by the hand controllers varies nth the game be ing played Each pistol grip hand control has several functions which determine the action seen on the screen Squeezing the trigger activates a switch for shooing as in Gunfight or placing a trace on the screen as in Scribbling The knob on top of the control can be moved in 8 directions forward backward left right and at 45 degree angles These motions determine the movement of the image on your scre6n Rotating this knob positions the cowboys hand during Gunfight etc Review hand control actions for each individual game Notice that the knob moves easily Under no circumstances should the knob be forced Figure 6 Figure 7 Hand Held Top View GENERAL SPECIFICATIONS Microprocessor Z 80 Memory RAM Scratchpad 4K Bytes ROM Resident 8K Bytes ROM Cassette 8K Bytes Max Inputs Calculator Keypad 24 Keys Dial 4 Joystick 4 Light Pen Bar Code Reader Provision Output Graphics Resolution 16 320 Configuration 160 x 102 Display Color Black and White Number of Colors 256 Output Audio 1 Channel Triple Tone Tremelo an
8. PA 1 SERVICE MANUAL PROFESSIONAL ARCADE FUN amp BRAINS TABLE OF CONTENTS Features 3 Connection to 7 Hand 85 9 System Operation 11 Disassembly 15 Glossary of Computer Terms 17 Mother Board Parts List 19 Final Cabinet Parts List 22 Layout Schematic 23 FEATURES AUTOMATIC TV PROTECTION The Bally Professional Arcade is designed with a TV protection circuit If the unit is left unattended for approximately five minutes the Bally Professional Ar cade will automatically blank the screen and thus prevent any damage to a televi sion receiver To regain operation all that is needed is to press any key on the calculator keypad PAUSE The Bally Professional Arcade includes a pause feature To operate the pause feature during the play of a game simply press the clear C key Upon return press clear C again to resume the game will appear on the screen at the exact point at which it was when the pause was initiated REMOTE GAME SELECTION All of the keypad entries required to select and initiate a game may be made using the 1 hand control Turn the power switch on and a listing of the games menu by number should appe
9. V 1MFD 50V 250 100MFD 16V 4MFD 50V 250 1MFD 35V 1MFD 50V 250 100PF 50V 27 50V 5 22PF 50V 33PF 50V 5 039MF 50V 470PF 50V 19 0066 851AX HVSD 0066 851 AX HVSC 0066 851 AX HVSB 0066 851AX HVSA 0066 700AX XXCX 0066 473XX XXCX 0066 124BX XXWX 0066 643AX XXCX 0066 643AX XXCX 0066 968AX XXAX 0066 463XX XXCX 0066 453XX XXCX 0066 502XX XXCX 0066 502XX XXCX 0066 463 0066 823XX XXCX 0066 115XX XXYX 0066 116XX XXYX 0066 117XX XXYX 0066 24 0066 823XX XXCX 0066 823 0066 967 0066 308XX XXWX 0066 754AX XXCX 0061 297EX 5EBX 0061 132H8 1J5C 0061 322CX 5EBX 0061 207D4 4ERX 0061 193G6 4ERX 0061 132H8 1J5C 0061 233DX 5E2X 0061 132H8 4ERX 0061 163G6 4ERX 0061 132H8 4ERX 0061 043H6 1J5X 0061 028H2 1J5X 0061 025H6 1J5X 0061 020H2 1J5X 0061 117H2 1J5X 0061 061 H6 1J5X Component C48 C49 C50 C51 C52 C55 C56 C61 C62 C64 C65 C106 R11 R12 R13 R14 R15 R16 R17 R18 R19 R21 R22 R25 R26 R31 R32 R33 R34 R35 R36 R37 R38 R39 R40 R42 Q1 Q2 Y1 Description AMFD 50V 250 50V 20 1MFD 50V 250 22PF 50V 100PF 50V 15MFD 20V 1MFD 50V Z5U RESISTORS 27ohm 1w 596 240ohm 5 150ohm w 5 2K ohm 5 1M ohm 5 10k ohm yw 5 2 2k ohm 5 22k ohm 5 11k ohm 5 330 ohm VW 5 82 ohm 5 62 ohm VW 5 47 ohm 5 ik ohm 5 150 ohm 5 2k ohm Vw 5 6 2k ohm VW 5 8 2k ohm 5 ik oh
10. ar on the TV screen 1 Press the trigger This signals the Arcade that you wish to use remote game selection A red number will appear in the lower left corner of the TV Screen 2 Twist the knob on the hand control to change the red number Adjust the knob until the number of entry that you want is shown 3 Press the trigger again This time it will register your choice with the Bally Professional Arcade When a game is over you can start another game by pulling the trigger to get the menu Then pull trigger adjust knob and pull trigger again to enter your choice RESIDENT GAMES Gunfight Gunfight is a two player game and uses the hand controls numbered 1 and TO HAND CONTROLS Joy STICK oi elis Walks the gun fighter around the screen KAOB pas a tp oed e Raises and lowers his arm THOGOE Shoots 1 Each player s score E sassa 10 00 488488 2 The shots remaining 3 Ten second timer starts after either player runs out of ammo 4 Each scoring set will have different objects appear on screen between the gunfighters Your gunfighter will be able x to hide behind cacti trees and even a covered wagon Checkmate 0 to 4 players Scoring is accomplished as indicated in the following example In a game with four players the first player to be eliminated scores zero and the remaining three score one point each The next player eliminated also scores zero and the remain
11. are maskable or nonmaskable A maskable interrupt may be delayed until a mask bit is lowered input output hardware that interfaces a microprocessor system with the outside world Iterative Loop a programming technique whereby a process is repeated a specified number of times Jump a programming instruction that breaks the consecutive instruction pro gramming sequence and resumes elsewhere in the program Machine Language Numerical coding representing instructions usually in the form of groups of bytes used by the microprocessor Peripheral a unit operated with a microprocessor system such as a keyboard or a printer 17 Port a place through which inputs and outputs either data or instructions are channeled A microprocessor can have more than one port of can address many Port size though is often specified in bits ranging from 4 to 16 bits Processor Status Word PSW a word of readily available status information provided to indicate the result of specific operations Program a set of sequential instructions that a computer follows Program Counter two 8 bit registers used to generate the 16 bit address The registers are called PCH and PCL and are used for the higher order and lower order bytes respectively PROM a programmable ROM in which a program is entered by the user before installation into equipment as opposed to a factory programmed ROM RAM random access memory a data storage devic
12. as 3 in the orange window The calculations appearing directly above this window are the beginning of a printed video tape revealing each entry and function performed This unique feature of the calculator will continue to record and store your calculations up to a limit of 100 lines allowing for lengthy and complex calculations In addition you may recall to the TV screen any previous calculation by simply pressing and holding the scroll backward key until your calculations appears At this point it would be best to use the scroll forward key 4 and return to the end of the video tape prior to any further calculations Should you start new calculations while in the middle of the video tape they will be added in their proper location at 4 the end Therefore you will not see them as before Your only visible indication will be the line entries as they appear in the orange window To clarify the video tape must be scrolled forward until the end of tape is reached Should your calculations exceed the 100 line limit data at beginning of video tape will be omit ted as new date is added thus maintaining a tape of 100 lines Calculator Functions C Clear Key Removes all previous calculations including memory storage CE Clear Entry Removes only the last entry from display CH Change Sign The key changes the sign of the displayed number Negative numbers will ap pear in red MS Memory Storage Adds displ
13. ates 13 8K SYSTEM 8K BYTE CASSETTE ROM IEEE EXPANDER BUS ON OFF SWITCH CUSTOM INPUT OUTPUT CUSTOM ADDRESS POWER EE CONNECTOR KEY PAD CUSTOM DATA HE MoDULATOR CONNECTOR POWER SUPPLY PLAYER NO 2 PLAYER NO 1 A SYSTEM BLOCK DIAGRAM gt LIGHT PEN ADDRESS 4K BYTE RAM 017 024 03 RF MODULATOR CONTROL HANDLES 1 4 EXPAND CONNECTOR PLAYER NO A Gren NO 3 Iran em SYSTEM ROM 14 CH 3 OR 4 TO T V RECEIVER LITE CONNECTOR CASSETTE CONNECTOR DISASSEMBLY PROCEDURE FOR REPLACING GAME BOARD 1 Using a magnetized phillips screwdriver remove the five 5 screws on the bottom of the cabinet figure 1 item 1 Holding the top and bottom sections together turn the cabinet right side up Lift up gently on the top section and it will separate from the bottom section On the left side of the unit you will see the R F Modulator figure 2 item 1 and the four 4 wire power connector figure 2 item 2 Remove the R F Modulator by lifting up on the left side of it and pulling outwards to the left The power connector can be removed by pulling it towards the rear of the unit 4 Using a magnetized phillips screwdriver remove the four 4 screws in the corners of the board figure 2 item 3 At this time the game board and keypad cassette assembly can be removed from the bottom of the cabinet 5 Remove
14. ayed number to memory 10 individual entries to memory storage can be made Each time the MS key is used it should be followed by pressing the appropriate number key 1 2 3 etc to establish numerical sequence within storage register MR Memory Recall Recalls number in memory to display Must be followed by appropriate number key to secure correct memory from storage 1 Scroll Moves video tape forward Scroll Down Moves video tape backward Decimal Enters a decimal point 5 Percent Calculates a percentage of the previous entry Calculator will display up to 10 digits to the left of the decimal point on your screen It will also store up to 10 digits to the right of the decimal which are not shown Scribbling Scribbling is a fascinating creative game By manipulating the various controls you can create a multi color pattern on the TV screen and draw or write almost anything you choose How to Start Press 4 on the keypad to get Scribbling on the screen Now that you ve chosen Scribbling the questions of players will appear You can choose from zero to four by pressing the appropriate number key on the keypad Before starting to scribble place the plastic overlay for the keypad into posi tion This overlay outlines the functions controlled by the keys during Scribbling If you select zero players the Arcade console will automatically trace an ever changing pattern on your TV screen and cont
15. d Vibrato Output Signal NTSC Standard Color Output Channels 3 and 4 Calculator Keypad 24 Keys Function Add Subtract Multiply Divide and Percent Memory 10 Separate Power Requirements Standard 120 VAC Power Consumption 12 WATTS Ave Additional Specifications with Bally Basic Videocade Language Basic Baud with Interface 300BPS Output Text Text Display 286 Text Capacity 26 x 11 10 SYSTEM OPERATION GENERAL The Bally Professional Arcade is a full color video game system based on the mass ram buffer technique A mass ram buffer system is one in which one or more bits of RAM are used to define a color and intensity of a pixel dot on the screen The picture on the screen is defined by the contents of RAM and can easily be changed by modifying RAM The system uses a Z 80 Microprocessor as its main control unit The system contains 4K Byte RAM and 8K Byte ROM The resident ROM has software for four games Gunfight Checkmate Scribbling and a five function 10 memory Calculator Additional ROM in cassette form can be accessed through the cassette connector Three custom chips are used for the video interface special video processing functions audio generation and keyboard and control handle interface The system will accommodate up to four player control handles at once Each handle has five switches and a potentiometer These switches are read by the Z 80 via the I O chip The signal
16. e that can retain and pro duce on demand any data placed in it Register a device that stores one word of data and often consists of several flip flops ROM read only memory a device that has data permanently entered into if to be outputted on demand R W read write a control output of the microprocessor that indicates if data are being transferred from the microprocessor to memory or vice versa Scratchpad an area of the main memory set aside for short and often done calculations Stack storage for data during subroutines or interrupts Stack Pointer two 8 byte registers containing the address of the top most re cent end of the stack Subroutine a program within a program that performs a specific often used function Vector a specific address loaded into a microprocessor s program counter to force the microprocessor to start processing at a specific address 18 MOTHER BOARD PARTS LIST Component U24 U31 U32 C1 C2 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C47 Description Bally Part Number INTEGRATED CIRCUITS ROM 9316B HVSD HOM 9316B HVSC ROM 9316B HVSB ROM 9316B HVSA 74LS367 74LS04 Z 80 CPU 7415257 7415257 0 8304 741502 741500 741510 741510 741502 741574 Custom Address Custom Data Custom 74LS174 74LS74 74LS74 DM81LS95 MK4096N 15 RAM 75361AP CAPACITORS 1500MF 25V JMFD50V 250 10 000 10V 15 MFD 20V 6 8MFD 35
17. ing two players each score another point After all other players have been eliminated the remaining player will have scored three points and the game is over HAND CONTROLS Joy 51 Moves your symbol horizontally vertically and diagonally en LEE No function BD gt 9 oneee No function 1 Each player s symbol and score 2 Each player s symbol on the playing field 3 The number of games remaining Calculator The programmable microprocessor unit in the Bally Arcade contains a 5 func tion 10 memory printing keypad calculator that scrolls on the TV screen The convenient algebraic entry system allows problems to be entered in the same order they are written If you want to calculate 3 4 5 you need only to press 3 4 15 After choosing the calculator by pressing 3 on the keypad the TV screen should show a white background and a long orange horizontal bar near the bot tom of the TV screen This represents the viewing window of the calculator The calculator is easy to operate and can add subtract multiply and divide Us ing these four basic functions we ll see exactly what takes place and how it looks on your TV screen Let us perform the operation 6 5 4x 3 7 by pressing in order the number and functions keys 6 5 4 x 3 117 Looking at your TV screen you ll see the answer the sum total of your calculation appears
18. inues until you press the reset key or the clear key The automatic television protective circuit will not function while in zero player mode When 1 to 4 player action is chosen you should see one to four colored squares on your screen Movement of these squares is accomplished by move ment of the Joy Stick in any of its eight directions Squeezing and releasing the trigger of the control will place a colored square anywhere you desire If you wish 5 to draw a line squeeze the trigger and hold Move the Joy Stick in the direction you wish to draw Rotate the top control knob to change the size and color of your square In the counter clockwise position of this knob you will see a large blue square As you begin to rotate in a clockwise direction the color will change to red then green and finally white Continue to rotate and the size of the square will decrease and again you will pass through the four basic colors One complete rotation from left to right produces 4 square sizes large to small and the 4 basic colors which in effect puts a 16 position switch at your fingertips Alternately squeezing and releasing the trigger while in motion produces a dot ted line To change from green in the display to orange press the clockwise rota tion key in the third row Green and hold until green becomes orange and release The color clockwise and counter clockwise keys appear in the first two rows top to bottom on the keypad the next
19. let 7 IV Plug each hand control unit into its appropriate plug on rear of console See figure 4 V Move console On Off switch on back of console to On position See figure 4 IV Move slide switch on TV adapter to Game position VII Turn on TV set and set Channel Selector to Channel 3 position The menu should now appear on the TV screen If not press the reset button You now have a choice of Gunfight or Checkmate Arcade Games a 5 function 10 memory printing calculator or Scribbling an exciting art form game Press the appropriate numbered button on the keypad to start the game of your choice If the menu doesn t appear check on the following Is the On Off switch on the back of the console in the On position Is the switch on the TV adapter in the Game position Is the coaxial cable securely inserted into the adapter switch Is the power supply cord securely inserted into a 120 volt outlet Is the flat twin lead wire properly hooked up to the back of the TV set Is your Channel Selector set on Channel 3 The Bally Arcade is factory set to operate on Channel 3 If there is interference from a Channel 3 TV station in your area you can change to Channel 4 by moving the slide switch of the RF modulator to position 4 and setting your channel selector to Channe14 This switch is located on the left side of your console See figure5 HAND CONTROL PLUGIN FIGURE SWITCH TV ADAPTER TO
20. m VW 5 3 3k ohm 5 8 2k ohm yw 5 3 3k ohm 5 47 ohm 5 10k ohm 5 2K ohm 5 TRANSISTORS TIP 31 TIS 137 CRYSTAL 14 31818MHZ XTAL 20 Bally Part Number 0061 132H8 1J5C 0061 030H6 1J5X 0061 132H8 1J5C 0061 025H6 1J5X 0061 043H6 1J5X 0061 207D4 4ERX 0061 132H8 1J5C 0062 068F 3 1XXX 0062 135B3 1XXX 0062 122D3 1XXX 0062 193B3 1XXX 0062 323B3 1 XXX 0062 227B3 1XXX 0062 195B3 1XXX 0062 243B3 1XXX 0062 229B3 1XXX 0062 144B3 1XXX 0062 104B3 1XXX 0062 095B3 1 XXX 0062 086B3 1 XXX 0062 179B3 1XXX 0062 122B3 1XXX 0062 193B3 1XXX 0062 217B3 1XXX 0062 223B3 1XXX 0062 179B3 1XXX 0062 203B3 1 XXX 0062 223B3 1XXX 0062 203B3 1XXX 0062 086B3 1XXX 0062 227 B3 1XXX 0062 193B3 1XXX 0065 485XX XXMX 0065 500XX XXMX 0069 079XX XX2X Component CR1 CR8 CR9 CR28 VR1 VR2 VR3 VR4 51 J1 J2 J5 J6 J7 Description Bally Part Number DIODES IN4004 0064 030XX XXPG IN4148 0064 048XX XXPX VOLTAGE REGULATORS LM342 P 15 0066 024BX XXAX LM342 P 10 0066 025BX XXAX UA78GUIC 0066 250BX XXBX LM320 MP 0066 026BX XXAX SWITCHES on off switch 0017 00032 0049 Reset switch 0017 00032 0048 JACKS R F Modulator Conn 3000 16337 0000 Player Handle Conn 0017 00021 0291 Cassette Conn 26 Pin 0017 00021 0273 Lite Pen Conn 3000 16336 0000 MISCELLANEOUS Oscillator Fence 0620 00114 0000 Thermalloy Heat Sink 0068 031XX XXAX Thermalloy Heat Sink 2 0068 032XX XXAX Keyboard 24 Button 0017
21. mpromise between the user s thoughts and the numerical notation of the microprocessor Assembly language is the closest technique to the actual numerical codes that still retains some speaking language characteristics Bit a minimum logic element A binary number of either O or 1 Branch depending on the status of a particular bit in the status register the pro gram will jump by the indicated amount if the condition is met or merely incre ment if not Bus a group of wires that carry related binary signals usually a word as in a 16 wire address bus A bus can be bidirectional as in the case of a data bus Byte a word consisting of eight bits Cross Assembler program on a larger computer that allows a microprocessor programmer to use assembly language The assembler reduces the program to the machine language Decoder usually a device that detects a certain specific address on the ad dress bus DMA direct memory access a process in which a microprocessor is removed temporarily from a system to allow data to be transferred rapidly in or out of memory without microprocessor control EPROM A PROM that can be erased and reused indefinitely Most EPROM s are erased under ultraviolet light and can be recognized by the clear cover over the silicon chip Hex short for hexadecimal numbers calculated to the base 16 Interrupt an external signal that causes a microprocessor to jump to a specific subroutine Interrupts
22. receives a 7 MHZ fre quency from the clock driver circuitry and this frequency is divided down by counters to generate a frequency of 1 7 MHZ which is used throughout the system The 1 7 MHZ is shown on the schematic as O The data chip also generates Pixclock PXCLK which is 3 547 MHZ This is used to synchronize the RAM s with the data chip to insure the proper timing and colors when data is being dumped from the RAM s for display on the Screen The data chip also generated R Y B Y and the composite video which is output to the RF modulator CHIP The Z 80 communicates with the I O chip through input and output instruc tions The state of an 8 x 8 switch matrix can be read through the Switch Scan cir cuit When an input instruction is executed one of the 500 507 lines will be ac tivated When a line is activated the switch matrix will feed back 8 bits of data on 510 517 This data is in turn fed to the 2 80 through MUXDO MUXD7 The Z 80 can read the position of the four hand control potentiometers through the Analog Digital Convertor Circuit These pots are continuously scanned by the A D Convertor and the results of the conversions are stored in a RAM in the A D Convertor Circuit The Z 80 simply reads this RAM with input instructions Also included in the chip are the audio registers The Z 80 loads data into the Music Processor with output instructions This data determines the characteristics of the audio that is
23. rithmetic and logic operations registers to serve as easily accessible memory for data frequently manipulated an accumulator a special register closely associated with the ALU address buf fers to supply the control memory with the address from which to fetch the next instruction and input output buffers to read instructions or data into the microprocessor or to send them out MICROCYCLER The task of the microcycler is to combine the 16 bit Address Bus and the 8 bit Data Bus from the Z 80 into one 16 bit Microcycle Data Bus to the Data Chip Ad dress Chip and I O chip This was done to reduce the pin count on the custom chips 11 ADDRESS CHIP The address chip has several tasks 1 Itprovides an interface for the light pen 2 t multiplexes the 16 bit Microcycle Data Bus from the Z 80 into a 6 bit bus for the RAM This is necessary because the RAM s only have 6 pins available for information processing 3 It synchronizes with the data chip to insure that the data being dumped from RAM for display on the screen is displayed at the proper time 4 Because of the slow speed of the microcycler and of the address chip the address chip generates a wait signal to the Z 80 telling it to wait until the instruction being processed is completed before the next instruction is started DATA CHIP One of the data chips most important functions is to generate the correct clock frequency used by the rest of the system The data chip
24. s from the potentiometers are changed to digital information by an 9 bit Analog to Digital Convertor within the I O chip Provisions for expansion are provided for a full keyboard via an IEEE Bus along with a separate input to accommodate a light pen OPERATION When the Bally Arcade is turned on the Z 80 microprocessor begins executing instructions out of ROM This ROM can also be from a cassette that is plugged in to the cassette connector The first thing the Z 80 does is write data into the RAM so that the menu appears on the screen What is seen on the screen is a con tinuous dump of the data in the RAM at that instant The data in RAM is not exact ly the same data that the Z 80 pulled from ROM The data is modified along the way by the Z 80 dependant upon the state of the switches knobs or triggers Depending on the state of these the 7 80 makes decisions and modifies the data accordingly on the way to the RAM MICROPROCESSOR CPU The task of the microprocessor is to receive data in the form of binary digits 1 s and O s to store the data for later processing to perform arithmetic and logic operations on the data in accordance with previously stored instructions and to deliver the results to the user through an output mechanism A block diagram of a typical microprocessor would show the following units A decode and control unit to interpret instructions from the stored program the Arithmetic and logic unit or ALU to perform a
25. the silver clips that are attached to the edges of the shielding figure 2 item 4 After the clips are removed the metal shielding on the bot tom of the game board can be removed 6 Turn the board over and remove the four 4 remaining phillip screws that secure the keypad cassette assembly to the game board figure 3 item 1 7 Holding the two pieces together turn them over and carefully lift the keypad cassette assembly away from the game board 8 Holding the keypad cassette assembly in your right hand press down gently on the keyboard itself with your left hand and slide the keyboard completely out 9 Remove the reset button and the remaining plastic shielding by pulling them up and off gently 10 Reverse the above steps to install a new game board IMPORTANT NOTE Insure that all shielding is in place and secure to conform to FCC regula tions 15 Fig 2 UNIT WITH TOP REMOVED 1 A F Modulater 3 Four 4 Philips screws In of board 2 Power Connector 4 Silver clips Fig 3 BOTTOM OF GAME BOARD 16 GLOSSARY OF COMPUTER TERMS Accumulator a register in the microprocessor that operates on data It is so called because these registers were first used to accumulate totals Address specific memory location that is called out by the program counter ALU arithmetic and logic unit the circuitry that performs the manipulations on data held in the accumulator Assembly Language a co

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