TAPR Open Hardware License
This is an Amiga 4000 A3630 CPU Card reimplementation, simpler 2-layer board that supports only 68030/68882 in PGA package. I am currently building a replica A4000 board and I want a simple way to test it. I could not find a used A3630 card and testing it on an expensive 68060 CPU card is out of the question, I wouldn't want to burn such an expensive card. So I decided to build a A3630 reimplentation on my own. By the time I was half-way I found out that it was already reverse engineered by John "Chucky" Hertell at: http://www.reamiga.info/?page_id=44. Furthermore, after about a few weeks of trying to understand the schematics by looking at Chucky's board, I found the actual A3630 schematics on https://www.amigawiki.org/dnl/schematics/A3630.pdf! That showed me many mistakes I had made and allowed me to clean up my own schematics. In the process I ended up redoing the schematics and the board from scratch.
In any case, I continued with my design as it is simpler than the original A3630, it doesn't offer the choice of 68020/68030 nor different choices of PLCC/PGA FPU. I went for PGA versions for both, as they are much easier to solder by hand than QFP (I have not mastered drag soldering yet), not to mention much cooler looking. A feature I kept though is the choice of using a crystal for the CPU/FPU if running on a different frequency than the 25Mhz default. Ideally total cost for the board should be slightly less 100EUR, incl. CPU/FPU. As mentioned this is a 2-layer board. The original A3630 is 4-layer (middle layers are GND/VCC). I don't think it's really needed in this case as the frequencies are quite low. Although I have not tested that claim yet and I may be wrong.
In the process, I created a few parts/footprints for the following items:
NOTE: This is still not reviewed and untested! Do NOT try it out on your Amiga yet! Consider this an alpha release! You have been warned! Note 2: This is my first average complexity hardware project. I'm pretty sure I've made many design mistakes in the schematics/PCB. Comments and suggestions to improve it are welcome.
|3||KEL 8817-200-170S-F A3640 replacement PCB connector||CN606||KEL200 AMIGA 4000 CPU CONNECTOR||1|
|4||MC68881/MC68882 PGA||U2||MC68881 MC68882 PGA68||1|
|5||220pF||C102,C202||CAPACITOR 22UF 16V||2|