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A3630 reimplementation

2 months ago 125
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Description

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:

  • KEL200 connector, a 200-pin connector which is used to connect the CPU card to the Amiga 4000 motherboard (it should be the same in Amiga 3000 if I am not mistaken). However I am not sure this card makes much sense in the A3000 as it already has a 68030 CPU/FPU. Perhaps only if using a higher clock than the default 25Mhz. Link for the component here:

https://easyeda.com/component/6cd7654456d944538593b212cc868df5

  • MC68030 PGA. There are already a few parts available in EasyEDA but I needed all the pins as they appear in the A3630 schematic.

https://easyeda.com/component/777c712c29d84dcaa5a63b3431f4d7e8

  • MC68881/2 PGA. Same reason

https://easyeda.com/component/8b5fda783f7240aaa5cb2edf46755f96

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.

Documents

PCB_2020-09-24_09-03-58

Main Sheet

BOM

ID Name Designator Footprint Quantity
1 22uF C203,C103 CAP-D4.0×F1.5 2
2 OSCILLATOR U3 CRYSTAL-SMD-7X5 1
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
6 0.22uF C101,C201 CAPACITOR_SMD0805_HANDSOLDERING_REVA_DATE21JUN2010 2
7 0.01uF C301 C0603 1
8 MC68030RC PGA U1 MPGA128 1
9 22R R3 R0603 1
10 JUMPER-CLK JP1 1X03 1
11 4.7k R1,R4 R0603 2
12 100R R2 R0603 1

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你现在访问的是EasyEDA海外版,使用建立访问速度更快的国内版 https://lceda.cn(需要重新注册)
如果需要转移工程请在个人中心 - 工程 - 工程高级设置 - 下载工程,下载后在https://lceda.cn/editor 打开保存即可。
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