REV 3 - REV 5 - The beginning (ST536)

Post by **exxos** » 29 Nov 2025 23:51

I think your on the wrong point on the SDRAM..

You probably should upgrade to the latest ROM version as well.

coonsgm · Post by **coonsgm** » 30 Nov 2025 03:22

Aha! I miscounted the SDRAM pin....it was the 11th. Fixed. Now I just need to for the the new AT27C4096's to get here faster....4 on order from Digikey.

Post by **exxos** » 30 Nov 2025 10:41

coonsgm wrote: 30 Nov 2025 03:22 Aha! I miscounted the SDRAM pin....it was the 11th. Fixed. Now I just need to for the the new AT27C4096's to get here faster....4 on order from Digikey.

Have you tried booting with the ROM you have as it should still pass TT RAM test as a minimum?

coonsgm · Post by **coonsgm** » 30 Nov 2025 12:35

exxos wrote: 30 Nov 2025 10:41
coonsgm wrote: 30 Nov 2025 03:22 Aha! I miscounted the SDRAM pin....it was the 11th. Fixed. Now I just need to for the the new AT27C4096's to get here faster....4 on order from Digikey.
Have you tried booting with the ROM you have as it should still pass TT RAM test as a minimum?

See below images the system freezes just after copying the ROM to TT RAM. It doesn't make it to the TT RAM test. The second image is the error message when trying to boot EmuTOS 1.4. It recognizes 60mb of "Fast RAM".

IMG20251130072221.jpg

IMG20251130072824.jpg

coonsgm · Post by **coonsgm** » 30 Nov 2025 12:49

I did make certain I have continuity between the correct PLD pin and SDRAM pin and that there aren't any bridges on the PLD (from the remove and replace with the 288)

Post by **exxos** » 30 Nov 2025 12:51

coonsgm wrote: 30 Nov 2025 12:35 See below images the system freezes just after copying the ROM to TT RAM. It doesn't make it to the TT RAM test.

Is the floppy drive connected? I've seen it lockup at that point as is when it accesses the floppy drive next.

The second image is the error message when trying to boot EmuTOS 1.4. It recognizes 60mb of "Fast RAM".

Weird.. Don't know why the address is right at the top end. Nothing should be trying to access that high up.

It makes me wonder if EMUTOS stops checking for ram when it hits bus error or it keeps trying the whole address range? If that's the case, it would corrupt the ROM shadow in ram. Maybe someone knows?

coonsgm · Post by **coonsgm** » 30 Nov 2025 12:53

exxos wrote: 30 Nov 2025 12:51 Is the floppy drive connected? I've seen it lockup at that point as is when it accesses the floppy drive next.

Yes, the floppy drive is connected, but IDE is disconnected.

Post by **exxos** » 30 Nov 2025 12:59

coonsgm wrote: 30 Nov 2025 12:53 Yes, the floppy drive is connected, but IDE is disconnected.

Should be fine at that...

Looks like TTram is copying fine now which is good..

Have you tried the 536 in a H4 or H5 and make sure you have 5.2v on the 5v rail on the PSU.

coonsgm · Post by **coonsgm** » 30 Nov 2025 13:03

I've tried in both the Mega ST and the H5. Same results. I boosted the voltage to 5.21v, same result.

Could the SDRAM been damaged by my previous botched connection to the pin next to the correct one?

Post by **exxos** » 30 Nov 2025 13:19

coonsgm wrote: 30 Nov 2025 13:03 Could the SDRAM been damaged by my previous botched connection to the pin next to the correct one?

I don't think so.. It would have shorted the clock chip enable to the clock, chip enabled is low driven by the PLD.. It wouldn't have passed ROM copy if the SDRAM was toast.

You definitely used the beta1SS firmware?

I don't know what else it could be..

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REV 3 - REV 5 - The beginning (ST536)

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Re: REV 3 - REV 5 - The beginning (ST536)

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Re: REV 3 - REV 5 - The beginning (ST536)

Re: REV 3 - REV 5 - The beginning (ST536)

Re: REV 3 - REV 5 - The beginning (ST536)

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