Before you start you will obviously need a set of eight memory chips to double the memory (from 256K to 512K) in your machine, probably now only available from a PCW specialist, handle them gently to avoid bending the legs on the chip, although I find them not to be as delicate as is suggested by other writers on this subject. Remove the back of your machine and slide out the CPU/MEMORY BOARD, it
will then be noted that the bottom row of sockets are empty and awaiting tasty chips. The chips can be fitted, in any order as they are all identical, with the board left where it is but it is much easier to pull off the five plugs and work with it on a flat surface. Look at the chip and note which end has the half moon indentation, as this needs to tie up with the half moon cut-out on the socket, carefully offer the chip to the socket ensuring that all the legs go into their appropriate holes, then push home. Work from one end to the other, neither end has been found to have any advantages, although there might be a difference for someone who is left handed. After fitting all the chips you will need to alter the small switches on the most commonly found Mark 2 board (largish 5 pin plug at the top of the board).
The settings for the switches are:-
256K
512K
A
ON
A
OFF
B
OFF
B
ON
C
OFF
C
OFF
D
ON
D
ON
Should you be unlucky enough to have a Mark 1 board (largish 4 pin plug at the top of the board) you will not find any switches but instead wire links. You will need to alter the continuous wire in
LINK 1 by soldering as shown below.
The link layout is:-
256K
512K
LINK 2
LINK 2
C---
---o
D
C---
---o
D
LINK 1
LINK 1
A
o---
---B
A---
---o
B
GERMAN PCW8256. Owners of the German version of the PCW8256 (which as we all know was issued within the U.K. when stocks of the British version ran out) will note that their CPU/MEMORY BOARD has metal shields either side, you will only need to removed the shield that faces the disc drive before the memory chips can be replaced or fitted. All of these boards so far encountered are of the Mark 2 type so follow the instructions relating to this board. THE FINAL STAGE: Re-fit the CPU/MEMORY Board (if you removed it) but leave the back of the machine where it is, just in case you have made a blunder. Now is the time to test your handy work, boot the
machine up using your CP/M plus (version 1.4) Start-of-Day disc and see how much memory is reported -- it should now be 368K. Then re-boot using Locoscript (version 1.20) as supplied with the machine and it
should now show around 352K of space on drive 'M'. I always use Moonstone's excellent programme 'PCW CHECKUP' to give the machine a complete test when extra memory has been fitted and would advise
anyone else to do likewise. NB. You can add an additional 1.5MB of memory (to give you 2MB) to your 8256 via a backpack but these are extremely difficult to find now.
PcW9256.
The 150ns memory chips as supplied for the PCW8256 work fine in the PcW9256, but gaining access is far more complicated and not for the faint hearted. The disassemble/reassemble process is left upto the reader but I will offer a little advice on fitting the chips. When the lower board has been extracted and the top metal shield removed from it, you will have access to the empty memory sockets.
Fit the chips with their half moon indentations facing the smaller existing 100ns memory chips and corresponding to the half moon cut-outs on the sockets. You will then need to remove the jumper marked 'LK10' (see drawing) and it might be wise to put this jumper in a safe place, but if lost - no problem - as it is a common PC type, available anywhere. Once your machine has been very carefully put back together (do avoid damaging in anyway the shield between the two printed circuit boards) you can use the small programme titled 'RAMTEST' available on the later versions of the Locoscript start-of-day discs to check your handy work or use Moonstone's programme 'PCW CHECKUP' to give your machine a thorough testing.
DK'TRONICS 256K RAM PACK FOR THE CPC.
Owners of the DK'Tronics 256K Memory Pack having trouble with the RAM chips inside their unit might be interested to know that it uses the same chips as fitted as standard to the PCW8256/8512 and can use these chips as replacements. They are easy to obtain and cheap to buy. The DK'Tronics Silicon Disc Pack would also appear to use the same Memory chips, but this only noted from viewing one example.
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