exxos's Atari, Amiga & retro forum

For the moment I have an issue - my recompiled firmware doesn't work.
Looks some libs or environment incompatibility. I will check and solve it later.

In meantime, I got digital analyser and recorded the boot session on ACSI port of STF and STE. I have some observation, maybe someone from you can review and find some conclusions.

As base I followed by instruction for test ST hardware: https://github.com/retro16/acsi2stm/blo ... hooting.md
1) No ACSI2STEM connected:
* STF: shows exact 8 CS pulses with perfect timing 250ns/50ms,
* STE: 8 CS pulses with timing 250ns/120ms.
The rest of signals like A1, IRQ, DRQ, ACK corresponds perfectly to CS as required on both.

The question the ACSI2STM is ready to have 120ms spacing on init? Or we have to find a reason why 120ms spacing in STE. Yes instruction says 50 ms more/less, but it's more then two times more!!!

2) Connected ACSI2STM
* STF: here both devices start talking and it works,
* STE: I can find 6 CS pulses, one "coated" with low A1 then, assume ACSI2STM sends low IRQ. What is really strange to me. It looks some way the ACSI2STM is not ready for my STE timing. Not sure the reason is in degradation of ICs or caps?
Do you have any idea how to explain it?

I can share captured signals if someone want to looks into.

Quick follow up to the ACSI2STM problem on my wonky STE. When I recapped the PSU 4 years ago I did it to factory (Mitsumi) spec. I was recapping a Mitsumi PSU for a mate and did it to Exxos spec, old mate bought a wad of components for the job so I decided to rerecap the PSU and another I have in a daily driver ST.
Well bugger me if the ACSI2STM now works flawlessly. All that changed was the recap spec and it fixed the only problem the machine had, ACSI2STM. As a plus its tidied up the video on the mongrel daily driver too. 8-)

atari030 wrote: 05 Feb 2025 23:23 Quick follow up to the ACSI2STM problem on my wonky STE. When I recapped the PSU 4 years ago I did it to factory (Mitsumi) spec. I was recapping a Mitsumi PSU for a mate and did it to Exxos spec, old mate bought a wad of components for the job so I decided to rerecap the PSU and another I have in a daily driver ST.
Well bugger me if the ACSI2STM now works flawlessly. All that changed was the recap spec and it fixed the only problem the machine had, ACSI2STM. As a plus its tidied up the video on the mongrel daily driver too. 8-)

capacitors recap specs can change things for Atari computers..... it's not just "let's smooth the signal here and there".

Yup. But what is interesting is another identical (as an Atari 1040STE can be) has an issue and the other does not. Tolerance is an important factor.

Reminds me of the old guitar POT debate. This model CTS sounds better than that model OAK etc, etc when they are all 250k +/- 10%.

@atari030 it could simply be voltage drop? The PSU having better output and less noise. I suppose that would clean up the TTL logic levels of most data transmission in the system?

I wouldn't think so, all voltages tested good under load. I'm thinking noise on the ACSI bus.