ARM3 Upgrade Fitting and Operating Instructions
Contents
1. ARM3 Upgrade Fitting and Operating Instructions WARNING Both the Archimedes and the ARM 3 upgrade are static sensitive Exercise all possible anti static precautions whilst fitting the upgrade static damage is NOT covered by warranties If your Archimedes warranty is still valid 12 months from date of purchase then the ARM 3 Upgrade must be fitted by an approved Component Level service centre to maintain the Acorn warranty DISASSEMBLING THE ARCHIMEDES Be sure to disconnect all cables from the Archimedes case particularly the mains power and monitor power before proceeding Remove the three screws along the top of the rear of the computer and those either side of the front of the computer Slide the top cover carefully off towards the rear Remove the front fascia of the computer by unscrewing three screws along the front underside and one more on either side of the front Unplug the fascia wiring carefully before removing it If an expansion backplane is fitted then remove any expan sion boards and then the backplane Unplug the two bolts and three power connectors and then pull the back plane firmly upwards Remove the two screws which fix the diskette drive bra cket onto the metal bar at the front of the computer Take care not to lose either of the screws inside the computer Detach the diskette power and data cables by pulling their bodies towards the rear of the computer You should now be able to see the area o2. UN 4 ARM3 in the Boot sequence for your computer USING THE ARM 3 WITH THE PC EMULATOR in the PC Emulator vesions 1 30 and later the emulator can be started from the desktop by double clicking on the PC application This action will kill off all relocatable modules that have been loaded into RAM by the user including that which controls the ARM3 cache so the PC Emulator will not get the benefit of the ARM3 To avoid this the PC Emulator configuration must be changed as follows Open the PC application by holding down the Shift key and double clicking on PC The configuration file is stored in side the directory folder marked GenBoot open it by double clicking on that icon Load the file marked Config into a text editor such as Edit The file consists of a num ber of questions followed on the next line by an answer Y or N The line that says Perform RMClear is usually fol lowed by a Y to tell the system to clear the Relocatable Modules in RAM Change the line following this question to contain the single letter CAPITAL N Once you have made this change save the file back to where it came from in Fdit nress F3 and then Return Now when the PC Emulator is started it will not clear all the modules Note that since the system is no longer removing all the modules that are loaded you may find that the PC Emulator has insufficient memory available to it If this is a problem you may edit the Config file again an
3. USING THE ARM 3 UPGRADE WITH RisclX Versions of Risc iX numbered 1 13 and later will run if the above instructions are followed Earlier versions require the use Of a special version of the ARM3 control software to ensure correct operation with Unix You will need to install it instead of the Risc OS software follow these instructions and then double click on the ARM3 icon afterwards Hold down a SHIFT key and double click on the ARM3 application icon A series of files will be displayed in a new window Move the pointer to the file called CacheMdl and rename it CmdIROS and press RETURN Move the pointer tO the file called CmdlUnix and repeat the process above this time naming it CacheMd1 instead Close the ARM3 window and test it out by double click ing On it Risc iX will now run correctly To maximise the speed of Risc OS reverse the renaming process described above so CmdIROS becomes CacheMdl again gt Aleph One Limited The Old Courthouse Bottisham CAMBRIDGE CBS 9BA U K Tel 0223 811 679 revfitio92 Facsimile 0223 812 713
4. d change the response to the question Quit desktop for maximum memory to the letter Y In this case all applications will be stopped and their memory given up before the PC Emulator starts CONFIGURATION OF THE ARM 3 STATE The ARM3 application provides a new CONFIGURE option for the cache If you enter CONFIGURE CACHE ON then the computer will start up with the cache on similarly CONFIGURE CACHE OFF causes it to start up with the cache Off Entering CACHE alone causes the computer t0 report the present cache state as On or Off TECHNICAL DETAILS The cache control module provides five SWIs so that prog rammers can control the cache from their own programs SWI Cache_Control only uses bit 0 of the registers If the bit is 0 the cache is switched off if it is 1 the cache is switched on Three further SWIs provide access to the internal registers of the ARM 3 For each of these three calls RO contains a data word in which each bit represents a 2MByte chunk of the memory map Bit 0 represents the memory from amp 0 to amp 1FFFFF and bit 31 represents the chunk from amp 3E00000 to amp 3FFFFFF A bit set means the chunk is cacheable updateable disruptive a clear bit means that it is not The initial settings for these registers are carefully chosen so do not change them without good cause and knowledge of what you are doing The SWIs all take two parameters the cur rent value of the relevant register is logically AND
5. ed with R1 and then EORed with RO Thus to set the parameter put a new value in RO and set R1 to 0 To read the old value put 0 in RO and 1 in R1 Hex 1 is amp FFFFFFFF All these SWIs return the new state in RO The SWIs Cache_Cacheable Cache_Updateable and Cache_Disruptive determine how the cache behaves during accesses t0 various parts of memory If memory is marked as cacheable then reads from these locations are cached 10 space is not cached as it can change without the processor doing anything If memory is marked as updateable then writes to these locations update the value for that location in the cache if the data has been cached clearly this should not be the case for Read Only Memory If memory is marked as disruptive then any writes to that memory will cause the contents of the cache to be discarded This is necessary so that when the operating system writes to the memory controller to remap the RAM pages the cache is flushed of any invalid data It is important to note that mis use of these SWIs can have serious side effects including crashing the machine or making it run very slowly They should only be used by experienced and capable program mers who need t0 tune the cache to fit a specific application It is not necessary to use them to take advantage Of the higher speed offered by the Upgrade The final SWI is Cache_Flush which simply removes all cached information from the cache it takes no parameters
6. f the main circuit board previously obscured by the diskette drive Identify the large square 84 pin ARM 2 chip it has VL86C010 or ARM printed on it and the smaller square MEMC chip it has one or more of MEMC MEMC 1a or VL 86C110 printed on it before proceeding further MEMORY CONTROLLER UPGRADE MEMCt1a If your computer has a model number ending 1 such as 420 1 it will have a MEMC1la Memory Controller chip in it If your computer does not contain this version of the chip it will need to be fitted and tested before the ARM 3 upgrade NOTE that this is NOT optional the ARM 3 upgrade can not operate properly without this chip WARNING This upgrade must be performed by an Acorn Approved Service Centre in order not to void the warranty TO fit the MEMC 1a upgrade you will need a 68 pin PLCC chip extractor tool a MEMC la chip included in kit a pre programmed PAL chip included in kit a 33 Ohm resistor for A440 computers only included Fitting the MEMC1 a upgrade ON A440s ONLY With a pair of side cutters remove tran sistor Q14 from the board and then remove the three stubs of its legs from the board This obviates the need to remove the PCB or use a desoldering tool Form the resistor and then solder it onto the two holes as indicated in the figure On all models Remove the MEMC from its socket using the extractor tool BR noting its orientation Insert the new MEMC la from the kit wi
7. harder than you expect Nevertheless the circuit board is not infinitely strong so use your common sense or you could damage it TESTING THE UPGRADE You will need to reassemble the computer in the following order 1 the floppy disc drive bracket two screws and its two cables 2 the expansion backplane two screws three wires if present 3 the front fascia and wiring one plug and five screws Be careful to ensure correct alignment of the floppy disc drive as you do so inserting a disc helps to do this by bringing out the eject button 4 Double check that all internal parts of the computer are screwed down and wired up correctly 5 Re attach the monitor keyboard and mains power cables Switch on the monitor and then the computer The com puter should beep and some keyboard lights illuminate if all is well If not TURN THE COMPUTER OFF IMMEDI ATELY and go through the procedure above checking as you go before trying again If no picture appears on the monitor try switching the computer off and then On again whilst holding down the DELETE key this resets configuration memory to use a normal monitor Consult the User Guide for more inform ation on using different monitors Follow the instructions below and enjoy the increased speed of the computer USING THE ARM3 UPGRADE If you are using RISC OS 3 you do not need our software at all The operating system will detect the ARM3 Upgrade but see below about Configu
8. ring the ARM3 to work automatically The diskette supplied with the ARM3 Upgrade contains the application Arm3 which must be installed to allow select ion of the processor speed You can do this in one of several ways the most convenient is to configure your computer so that the application runs automatically as part of the boot sequence when you turn the computer on We describe how to do this below NOTE the diskette is usually packed BENEATH the plastic foam in the ARM3 box From the Desktop Enter the desktop and select the disc drive with the Arm3 support disc in it Double click on the Arm3 program and notice that a new icon appears on the right of the icon bar with the legend Arm3 Clicking select on this will change its state with the faster Cache On state appearing as a hare while the Cache Off state appears as a tortoise These spri tes appear in the applications Sprites file so you can swop them for others using Paint if you wish From the Supervisor command line To run the Arm3 application from the command line put the disc provided in Drive 0 and type in 0 Arm3 This will set up the application You can then use the commands CACHE ON and CACHE OFF to turn the extra speed on and off from the command line You will want to copy the Arm3 application onto your hard disc should you have one If you put it in the root directory then you can run it either by typing in RUN ADFS 4 ARM3 or by putting R
9. th the same Orientation Push it home with your thumb until it is flush within the socket Remove the existing PAL with a screwdriver or DIP chip extractor and replace it with the one from the kit again ensuring the same orientation Reassemble and test the computer BEFORE proceeding with the ARM 3 upgrade INSTALLING THE ARM 3 UPGRADE Using an 84 pin PLCC chip extractor and NOT A SUB STITUTE TOOL remove the ARM 2 chip from its socket Place the chip on an anti static surface out of the way SERVICE CENTRES please note that the ARM 2 chip still belongs to the customer and you should make arrangements to hold it for them or return it to them safely packaged as they see fit Remove the ARM 3 Upgrade from its packaging Orient the Upgrade correctly There is a chamfer On one corner Of the plug to fit a corresponding filled in corner in the socket The Aleph One Logo and lettering on the board should be the right way up when viewed from the front keyboard of the computer Place the upgrade plug ON the socket and establish visually that it is correctly aligned on the socket Using moderate force push the upgrade into the socket until you feel it click home EXCESSIVE FORCE SHOULD NOT BE NECESSARY examine the upgrade plug pins and the main circuit board socket again if you feel uneasy It will be very apparent when the plug is correctly fitted The upgrade is quite rugged so do not be alarmed if you have to push
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