REV 3 - REV 5 - The beginning (ST536)

flegmatik · Post by **flegmatik** » 04 Nov 2023 18:12

Thanks! The difference is noticeable.

capture28.png

olivier.jan · Post by **olivier.jan** » 08 Dec 2023 13:43

I was preparing the ST536 today (flashed latest firmware) but just realized my last 27c4096 was dead :pullhair:
I don’t know the wiring of the ST536: if I flash the custom TOS to, let’s say, a pair of SST39SF010 and install it directly on the motherboard will it work or the ROM must absolutely be in the PLCC socket ?

Post by **exxos** » 08 Dec 2023 14:08

olivier.jan wrote: 08 Dec 2023 13:43 I was preparing the ST536 today (flashed latest firmware) but just realized my last 27c4096 was dead :pullhair:
I don’t know the wiring of the ST536: if I flash the custom TOS to, let’s say, a pair of SST39SF010 and install it directly on the motherboard will it work or the ROM must absolutely be in the PLCC socket ?

I don't know what machine you are fitting it in... Of course whatever machine must be able to hold patched TOS206 and decode it.. But the ST536 does have the ROM_CE as a output wire so you can drive external ROM boards, but to my knowledge nobody has actually done it that way yet.

For example on the STFM if you have the DUALTOS board for 104/206 it has a external CE line which connects to the V2.x series booster for TOS206 decoding. So the same can be done with the ROM_CE output on the ST536... I thought ahead a little bit in that respect in case people broke the socket ;)

olivier.jan · Post by **olivier.jan** » 08 Dec 2023 14:25

It’s a Mega ST. I guess the ROM_CE is the little connector right next to the ROM socket on the ST536. I will try this over the weekend then. Thanks a lot. I found some 27c4096 on eBay in the meantime, but it will take a while to arrive.

olivier.jan · Post by **olivier.jan** » 08 Dec 2023 19:32

Actually, after modifying the jumpers to switch from a 6 rom setup to a 2 rom one, I realized the ST536 doesn’t fit when the ROM chips are inserted. I could add an extra socket to raise it but then the STGA plugged in the Mega Bus wouldn’t fit :headbang:
So let’s keep it simple: I have one PLCC dual TOS from your store with a vanilla 2.06. It will do until I receive the blank chips from eBay.
I guess I can start setting it up, from what I understand, it will be without Alt-RAM until I can flash the new TOS.

Post by **exxos** » 08 Dec 2023 19:49

olivier.jan wrote: 08 Dec 2023 19:32 from what I understand, it will be without Alt-RAM until I can flash the new TOS.

MAPROM should install alt-ram IIRC.
The main problem with vanilla 206 is, it does not handle the 030 caches. So at a minimum you need to probably use the disabled jumpers on the ST536 and disable it in the GEM menu if its there. Otherwise you could end up with all sorts of corruption problems relating to the floppy or hard drive access... Things might behave a little better with IDE.. But ultimately I just gave up with the thing and patched 206 with the cache stuff from TOS306 etc.

olivier.jan · Post by **olivier.jan** » 08 Dec 2023 21:31

Ok I was not using maprom so far, I was trying to get IDE to work.
It was rebooting immediately when trying to access CF card, so I checked the joints and cleaned a few suspicious ones.
I might have cleaned a bit too much as it’s not booting anymore…

I’ll repair using the microscope this weekend and will try with maprom.

olivier.jan · Post by **olivier.jan** » 09 Dec 2023 23:41

Some progress today but still no IDE and I’m not sure it’s a hardware issue.
I cleaned a bit the ST536 and as the iron was warm I built a second one. Now both are working correctly but I face the exact same problem on both with IDE:
- CF card is detected by HDDriver 11 and PPDriver
- Partitioning with PPDriver is immediately followed by a black screen and a few seconds later a reboot without action on the CF.
- Partitioning with HDDriver sometime works but most of the time black screens also.
- When partitioning works, I can read data, write small files but it black screens and reboot when trying to write files of more than a few kB.
- Installing driver to C works but it doesn’t boot from HD anyway.

I tried a few different CF, same results.
Will do some more tests tomorrow, I might try to flash an older firmware for the ST536 until I receive the chip to burn a proper modified TOS.

Post by **exxos** » 10 Dec 2023 00:28

Flashing older firmware will just add more problems . Sounds more like you have memory corruption. I don't know if you have done all the fixes for your mega or not ? I've never heard of accessing the IDE leading to black screen crashes before.

Post by **PhilC** » 10 Dec 2023 09:45

Just to interject quickly, it can be a bit hit and miss which CF cards work, so might be worth trying a different one.

Incompatible ones will cause the reported behaviour or no boot at all.

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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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