The latest member of the family

[rubber_jonnie]

@rubber_jonnie I'll also try to test my expansion (no RTC) and see how that goes...just in case!

Good idea.

[stephen_usher]

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]

Turns out I'm a numpty.

I was looking at the bloody RAM upside down :dizzy:

So it isn't A2 and A5, it's the data in/data out pins that look all kinds of wrong. D'oh.

[rubber_jonnie]

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.

Yeah, I'm off looking for that now...

Also I have loads of 41256 RAM like on the expansion board so I could try piggybacking.

[rubber_jonnie]

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.

[rubber_jonnie]

Also interesting, I found the RAM I need to do an on board upgrade if it comes to it. It was in a drawer of Atari stuff.

[stephen_usher]

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.

[rubber_jonnie]

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.

Definitely is.

I have been wondering if the card is not compatible with this particular issue Amiga, but that would be rather odd.

[stephen_usher]

Maybe a short between a high and low address line, or maybe one of the higher address lines not reaching the card?

[rubber_jonnie]

Maybe a short between a high and low address line, or maybe one of the higher address lines not reaching the card?

If there is I don't think it's on the card, it's super simple and looking at it with the magnifying glass, it looks just fine.