The PCB of the CPC 464+ is already prepared for using 128kB of RAM. So it is quite easy to upgrade to 128kB.
WARNING: You do this project at your own risk!
The following tools are needed:
Needed electrical components:
If you don't want to solder your RAM-Chips directly to the PCB you also need 2 IC-sockets (18pin).
First, you have to search for the following positions on the PCB: R28, R55, C12, C13, IC12 and IC13
At this positions, you have to remove the tin flux from the solderpoints.
Now you can connect the electrical components to the PCB:
The IC's have to be connected with the same orientation as the already existing RAM's.
You can test the new RAM-bank with the program below.
10 MODE 2:DEFINT b-z 20 PRINT"Bank:":PRINT:PRINT"Address: & OK!" 30 FOR bank=&C4 TO &C7 40 LOCATE 6,1:PRINT bank-&C3 50 FOR adr=&4000 TO &7FFF 60 LOCATE 11,3:PRINT HEX$(adr,4); 70 wert=255:GOSUB 120 80 wert=0:GOSUB 120 90 OUT &7F00,&C0 100 NEXT:NEXT 110 PRINT:PRINT"All banks OK!":END 120 OUT &7F00,bank:POKE adr,wert 130 OUT &7F00,&C0:POKE adr,255-wert 140 OUT &7F00,bank:wert2=PEEK(adr) 150 OUT &7F00,&C0 160 IF wert2<>wert THEN PRINT" ERROR!!!";:END 170 RETURN