Sweet success, card works 100% in different DUT(Amiga)

So I think the Amiga 500 I was testing with has problems.  I’m not sure precisely what or why but

Today, I dropped my new A501 replacement card into a known-working Commodore Amiga 500.  It fired up immediately no issues with booting, everything worked, no wonkiness, memory tests passed 100%.  This amiga has an accelerator card, and I was able to run 300 tests of pretty much the entire memory space on the card in about 5 minutes.  Everything worked without error.

I’d like to get more data points here before I call it DONE, but it looks GREAT to me!

I’ve got to start putting up some more information, update the schematics with a few small fixes, and do some more testing.

Good milestone tonight!



Amateur Electronics Design Engineer and Hacker


  • Does it work without the accelerator fitted? Or is it just an odd coincidence that the slower system was possibly having issues related to faster rise times, when the faster system does not..

    • Yup, fair point. However, the main issues I was having were related to the address bus which are amiga generated.

      The fast rise times would only be seen in the databus where I have appropriate 33 ohm series resistors designed to take the edge off of the fast driver.

      As mentioned, I definitely need more data points before saying it works.