exxos's Atari, Amiga & retro forum

JezC wrote: 31 Jan 2025 14:04 @rubber_jonnie I'll also try to test my expansion (no RTC) and see how that goes...just in case!

stephen_usher wrote: 31 Jan 2025 15:00 I'd fit the expansion, look up the address range it should have and then run Amiga Test Kit memory tester on that address range. It's possible one of the 41256 chips has become faulty. This is the least invasive test.

Then again, you know me. I try to exhaust all diagnostics before getting the soldering iron/desoldering gun out. :-) Been bitten too many times.

rubber_jonnie wrote: 31 Jan 2025 15:54 Ok, so piggybacking didn't work and when I tried to use the Amiga Test Kit to test the range where the trapdoor RAM should be (08000 to 0ffff) and it recognises it as a 512MB range, but as soon as I start the test it crashes the machine.

Interestingly though, the RTC on the trapdoor board is visible to ATK.

stephen_usher wrote: 31 Jan 2025 16:30

rubber_jonnie wrote: 31 Jan 2025 15:54 Ok, so piggybacking didn't work and when I tried to use the Amiga Test Kit to test the range where the trapdoor RAM should be (08000 to 0ffff) and it recognises it as a 512MB range, but as soon as I start the test it crashes the machine.

Interestingly though, the RTC on the trapdoor board is visible to ATK.

That's weird. It would suggest maybe an addressing problem where the external RAM is also being seen at a low address.

stephen_usher wrote: 31 Jan 2025 16:59 Maybe a short between a high and low address line, or maybe one of the higher address lines not reaching the card?