Some lower quality boards during that era are very quirky with RAMs as mentioned by Horun. I suspect it's more to PCB design than chipsets (well, Opti is good chipset but SARC I don't know). The traces from north bridge to SIMMs needs to be in equal length so that the signals arrive at the RAM chips in sync. If not then the timing will become more critical, hence the board becomes "choosy". Biostar being a brand name might have more stringent control on the traces in terms of PCB design.

Are you able to see the RAM timing in the Biostar BIOS? If so perhaps you could copy them over to your other 2 boards and try them out.

NScaleTransitModels wrote on 2020-06-20, 02:26:

I didn't get a shot, but it looked something like this: https://www.betaarchive.com/imageupload/2015-08/1440457032.th.22699.png […]
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I didn't get a shot, but it looked something like this:

Except it was right after the "preparing setup wizard" loading bar. This time, I'm having a different problem altogether. I'm not even sure if it has to do with the memory, or my graphics card (Cirrus GD5422), or the CPU running above spec. The setup completed without any crashes or freezes, but I'm getting strange graphical glitches upon reaching the desktop. Restarted and same deal. I even tried another graphics card, a GD5429, with similar graphics issues.
graphics glitch.png

I'm starting to think this board just has a bad chipset 😕

Could be, that is definately a video glitch, could be Vid card issue or driver. Cirrus chips are generally supported under Win9x.

NScaleTransitModels wrote on 2020-06-20, 02:46:

But I'm still not entirely sure why it won't work with the 9-chip 4mb SIMMs.

Yes makes no sense. Have to take care of the better half, will try to give some better informative info tomorrow.

kalohimal wrote on 2020-06-20, 03:19:

Some lower quality boards during that era are very quirky with RAMs as mentioned by Horun. I suspect it's more to PCB design than chipsets (well, Opti is good chipset but SARC I don't know). The traces from north bridge to SIMMs needs to be in equal length so that the signals arrive at the RAM chips in sync. If not then the timing will become more critical, hence the board becomes "choosy". Biostar being a brand name might have more stringent control on the traces in terms of PCB design.

Are you able to see the RAM timing in the Biostar BIOS? If so perhaps you could copy them over to your other 2 boards and try them out.

It just could come down to PCB design if both have reputable chipsets. Interestingly enough, the Biostar has less options and completely different options under advanced chipset setup. I'm not sure how they'd translate over to the Shuttle's BIOS options. The BIOS on the Biostar:

Slow refresh cannot be disabled, only set to 15, 30, 60, and 120. CAS and RAS are "normal" or "enabled". And no DRAM waitstates option 🤔

Stable BIOS settings on the Shuttle:

Yeah then I guess your options are quite limited, perhaps can use SIMMs with faster timing. Btw when CMOS is reset, my 486 board (also a cheap brand J-Mark board with AMI BIOS) will load up the default values which are conservative. The DRAM read wait state is set to 2 and write wait state to 3.

I was able to get the PCChips board to run at 33mhz using the jumper setting. No idea why it wouldn't work at 33 last time. However, as expected, it didn't fix the video glitch issue in Win95.

I'm starting to think the cheapass SARC chipset just doesn't like Cirrus video cards 😂 I swapped in the ATI Mach8 from the Biostar system and now the PCChips is fine. I wasn't able to duplicate the glitches I'd gotten on the Cirrus GD5422 and GD5429.

Ironically enough, the Biostar doesn't like the ATI at all (screen flickering). But then again, that board sadly has serious corrosion damage 😕

kalohimal wrote on 2020-06-20, 06:30:

Yeah then I guess your options are quite limited, perhaps can use SIMMs with faster timing. Btw when CMOS is reset, my 486 board (also a cheap brand J-Mark board with AMI BIOS) will load up the default values which are conservative. The DRAM read wait state is set to 2 and write wait state to 3.

IMG_20200620_142709a.jpg

Yeah my next step is to try 60ns 9-chip SIMMs once I receive them. Strange how my Shuttle board defaults to the tightest timings instead... and HDD type 17 (why 17 in particular 🤔) but I guess that's just how it is.

NScaleTransitModels wrote on 2020-06-20, 05:49:

Slow refresh cannot be disabled, only set to 15, 30, 60, and 120.

One of these all-to-often confusing setup option names. "15" is the settings you would call "disabled".

The setting actually seems to mean "refresh interval in microseconds". Industry standard is 15.6 microseconds per row, which yields 2 milliseconds per all 128 rows of a chip with 128 rows and columns (16 kilo-entries). This matches the usual requirement given in https://console5.com/techwiki/images/8/85/MK4116.pdf, see page 3, 4th to last entry in the table. Later chips are usually designed to be compatible with that, see for example http://pdf.datasheetcatalog.com/datasheet/sie … 117400BT-50.pdf (a typical 4Mx4 chip you would find on a 3-chip 4 Meg module). "It says 2048 refresh cycles, 32ms" on the front page. So it needs an 11-bit row number (can count from zero to 2047) on RAS-only refresh, and it includes an internal 11-bit row counter form CAS-before-RAS refresh. If you divide 32 milliseconds (per chip) by the number of refresh cycles needed to refresh the whole chip, you get 15.6 microseconds. This is why you need to choose 15. Higher numbers mean less refresh cycles, and thus slightly increased performance at the risk of memory corruption. You can safely use slow refresh if you have special memory chips for low-power application applications that are designed for being refreshed less often. Typical PC SIMMs do not have these special chips.

See https://www.datasheets360.com/pdf/-5753780607200078319 for a datasheet that includes a low-power version with an extended refresh period of 128ms per chip instead of 16 ms per chip (at 1024 cycles per chip). If all memory modules in your computer had low-power chips like the -S model in that datasheet, you can safely use the setting 120.

Shuttle: replace the caps with decent low-ESR electrolytics. PCChips: what brand/series are your replacement caps? If not a reputable brand/good series: replace them too.

mkarcher wrote on 2020-06-20, 08:22:

See https://www.datasheets360.com/pdf/-5753780607200078319 for a datasheet that includes a low-power version with an extended refresh period of 128ms per chip instead of 16 ms per chip (at 1024 cycles per chip). If all memory modules in your computer had low-power chips like the -S model in that datasheet, you can safely use the setting 120.

That gets me wondering how common those low-power SIMMs are, seeing as how most BIOSes of the time seem to support them. Doing a quick search on Ebay, I wasn't able to find any modules that were marked with a -6S, -7S etc. or any specified for low power. I did come across some on Amazon that mentioned low power consumption in the description, but even these don't have a -6S or any special markings: https://www.amazon.com/MEMORY-macintosh-Music … r/dp/B017YEI5TC

evasive wrote on 2020-06-20, 11:04:

Shuttle: replace the caps with decent low-ESR electrolytics. PCChips: what brand/series are your replacement caps? If not a reputable brand/good series: replace them too.

I thought that tantalums were more reliable than electrolytics on old hardware, as long as they're powered up every now and then? These are the two kinds I see on the Shuttle, and none of them seem damaged:

The first looks like a 10μF, 16V but not sure about the second one. Also I don't have access to a soldering iron at the moment, so the caps on the PCChips are still original. Uranus branded, 10μF 25V?

The 9 chip simms did you enable parity on the motherboard?

Opti and Sarc (pcchips) are not the greatest chipsets. I had best success with SiS mostly, but not yet on VLSI or VIA.

Cheers,

pentiumspeed wrote on 2020-06-20, 23:47:

The 9 chip simms did you enable parity on the motherboard?

Opti and Sarc (pcchips) are not the greatest chipsets. I had best success with SiS mostly, but not yet on VLSI or VIA.

Cheers,

You can enable parity with 9 chip but is not required to be enabled if your board supports non-parity simms. Most XT and 286 required parity but it was slowly dropped during 386/486 era for desktop computers.

pentiumspeed wrote on 2020-06-20, 23:47:

The 9 chip simms did you enable parity on the motherboard?

Opti and Sarc (pcchips) are not the greatest chipsets. I had best success with SiS mostly, but not yet on VLSI or VIA.

Cheers,

There are no options, BIOS or jumpers, for parity or anything that could be related on either board. The PCChips actually has a build date of 02/1994 on the sticker; I would've expected it to support non-parity (and have the option). But yeah, I believe my 9-chip's are parity and should still work in theory.

SiS motherboards seem pretty rare for 386's. Not sure if I've seen any recently. Do you know if UMC or "Chips" (not PCChips) are any good? They seem to be the most common, after Opti.

Horun wrote on 2020-06-21, 00:48:

Most XT and 286 required parity but it was slowly dropped during 386/486 era for desktop computers.

It seems most 386 boards still require parity. I was not able to get non-parity modules to boot in any of my 386 systems and I didn't see a parity option. My Dell 486P/50 (early 486 from 1992) also requires parity.

Also, speaking of chipsets (hope it's not too off topic): are there any known to be good for a 50mhz overclock via 100mhz oscillator? In particular, I'm looking at getting another board for this purpose with Opti 82C392 (like my Shuttle board), but stamped for 40mhz.

NScaleTransitModels wrote on 2020-06-21, 03:11:

There are no options, BIOS or jumpers, for parity or anything that could be related on either board. The PCChips actually has a […]
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pentiumspeed wrote on 2020-06-20, 23:47:

The 9 chip simms did you enable parity on the motherboard?

Opti and Sarc (pcchips) are not the greatest chipsets. I had best success with SiS mostly, but not yet on VLSI or VIA.

Cheers,

There are no options, BIOS or jumpers, for parity or anything that could be related on either board. The PCChips actually has a build date of 02/1994 on the sticker; I would've expected it to support non-parity (and have the option). But yeah, I believe my 9-chip's are parity and should still work in theory.

SiS motherboards seem pretty rare for 386's. Not sure if I've seen any recently. Do you know if UMC or "Chips" (not PCChips) are any good? They seem to be the most common, after Opti.

Horun wrote on 2020-06-21, 00:48:

Most XT and 286 required parity but it was slowly dropped during 386/486 era for desktop computers.

It seems most 386 boards still require parity. I was not able to get non-parity modules to boot in any of my 386 systems and I didn't see a parity option. My Dell 486P/50 (early 486 from 1992) also requires parity.

Also, speaking of chipsets (hope it's not too off topic): are there any known to be good for a 50mhz overclock via 100mhz oscillator? In particular, I'm looking at getting another board for this purpose with Opti 82C392 (like my Shuttle board), but stamped for 40mhz.

If memory serves, there were SIMMs with fake parity logic that never found errors, but simply generated the expected checksum from the actual data bits .

EDIT: Found a reference to those . http://bat8.inria.fr/~lang/hotlist/hardware/s … ver/parity.html

NScaleTransitModels wrote on 2020-06-20, 22:33:

I thought that tantalums were more reliable than electrolytics on old hardware, as long as they're powered up every now and then […]
Show full quote

I thought that tantalums were more reliable than electrolytics on old hardware, as long as they're powered up every now and then? These are the two kinds I see on the Shuttle, and none of them seem damaged:
shuttle 20200620_151033.jpg
shuttle 20200620_150954.jpg
The first looks like a 10μF, 16V but not sure about the second one.

I have already seen quite a few cases where they will simply transform into a little cloud of smoke. Powered on every now and then or not.

NScaleTransitModels wrote on 2020-06-20, 22:33:

Also I don't have access to a soldering iron at the moment, so the caps on the PCChips are still original. Uranus branded, 10μF 25V?
pcchips 20200620_145902.jpg

The only "Uranus" brand I can find is from India. But by the looks of the thing it was stripped from a portable radio somewhere in the last century. Replace them all please.