Changes

CPC 6320 / CPC 6512 - internal 320K / 512K for CPC 6128

1,681 bytes added, 14:03, 19 July 2023
[[File:CPC6320_schematics.jpg|thumbnail|none|CPC 6320 - schematics]]
 
 
=== Warning / Disclaimer ===
Although I have taken the utmost care preparing this documentation, I am no electronics engineer and did this only as a hobby project. I do not guarantee that it is error free and I accept no responsibility for damage to anyone’s hardware or other personal equipment or injury inflicted on you or others.
== Construction of the 320K (no PAL programming required) version ==
The required logic can either be built on a slim breadboard or with the help of a PCB that plugs into the PAL socket.
<br />
<br />
== Construction of the 320/512K (PAL programming required) version ==
 
For a 512K version the biggest challenge is, that when we replace also the first bank we must treat the first 64K as base RAM and the other 192K as extended RAM in a way that it is properly recognised by software.
 
While this can be done with logic ICs it would need to much space to properly fit into a normal CPC6128. Instead this is achieved with two PAL ICs. ATF16V8 ICs are easy to find and relatively cheap but need to be programmed with e.g. an Eprom programmer like the widely available TL866-II.
 
What you need:
 
* The PCB - [https://www.cpcwiki.eu/imgs/7/70/CPC6512_Gerber.zip PCB Gerber files]
* 2x Pin header 1x10
* 2x capacitor 100nF
* 2x ATF16V8 (or other PAL16L8 compatible ICs)
 
The assembly is pretty much identical to the PCB description above with the following changes:
 
* replace both RAM banks with 41256 RAM ICs
* connect all A8 pins on both banks so that all 16 ICs are fully parallel on all address lines.
* program two ATF16V8 ICs with the attached JED files and solder them to the PCB
* There is a connection from the PCB to D5. D5 is e.g. pin 29 on the 40007 socket. For other options check the schematics/Pinouts.
 
Note: It's also possible to use this PCB as a 320K version. In that case only replace the second (left) RAM bank and connect the D5 pad to GND (throughhole directly next to the D5 pad).
 
[[File:CPC6512 1.jpg|thumbnail|left]] [[File:CPC6512 2.jpg|thumbnail|right]] [[File:CPC6512 3.jpg|thumbnail|none]]
 
== References and links ==
* [https://www.cpcwiki.eu/imgs/4/40/CPC6320_Gerber.zip PCB Gerber files- 320K version]* [https://www.cpcwiki.eu/imgs/7/70/CPC6512_Gerber.zip PCB Gerber files - 512K version/PAL] 
* [[C't 512 KB internal RAM expansion|C't 512 KB internal RAM expansion]]
* [https://www.youtube.com/watch?v=b06CmqzrVE4 Repair video on Youtube that shows how to remove RAM ICs and add sockets]
144
edits