VOGONS


First post, by andromeda

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Hi,
What is the maximum size for the ram memory for this motherboard, there is no documentation on this motherboard on the internet
or else is there a utility to know the total of maximum ram.

Motherboard:
amaquest AP8548 486 DX2-66 4 ISA 16 bit, 3 PCI rev 2.0 24Mb RAM
4x72pin FPM
Bios Award v4.50PG,
string bios: 11/30/95-SiS-496-497/A/B-2A4IBADBC-00
board/bios-version: AP8548 BIOS VER.D12 RELEASE 12/21/1995 UM8669
Chipset: SiS-496-497/A/B //SiS 496/497
PnP (ACFG,ESCD,DMI): PnP V1.0/ESCD
Computer ID: FC, SubTyp: 01, BIOS-Level : 0

Thanks for your help.

Reply 1 of 14, by red-ray

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Looking in the SiS-496-497 datasheet it says as below, to me 255 MB seems strange though.

 DRAM Controller
- Supports 8 Banks Non-Interleaved Access for Single and Double Sided SIMMs up to 255 MBytes.
- Supports DRAM CAS Before RAS Refresh.
- Supports "Table-Free" DRAM configuration.
- Programmable driving current for the DRAM signals.
- Supports Symmetrical and Asymmetrical DRAMs.
- Supports 256K/512K/1M/2M/4M/8M/16M/32M xN Fast Page Mode and EDO DRAM.

Reply 2 of 14, by andromeda

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I have already looked at the datasheet but I doubt that my motherboard supports 256MB especially with a dx2-66,
the 32MB strips do not work, it displays 16MB and it crashes the system,
the 8MB goes without problem, at worst I think the maximum is 64mo or 32mo on this kind of motherboard but I'm not sure,
I have no idea.

Reply 3 of 14, by evasive

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We don't have that one listed in the database yet, would you post pictures of front and back + a bios dump in the 80486 bios thread please?
80486 BIOS image collection
It will be listed here:
http://www.win3x.org/uh19/motherboard/search

In the mean time I'll see if I have a manual somewhere that may answer your question about the maximum memory supported.

Take notice that EDO RAM support is flaky at best on boards this early, you have a better chance with FPM memory sticks.

Reply 4 of 14, by dionb

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What kind of 32MB SIMMs are you trying? (number and type of chips) And are they known-good in a different system?
Also you say "strips" - have you tested with a single 32MB SIMM?

It's unlikely that the memory density is the cause of these problems; as a rule if memory is too large for the controller, it just addresses the chips with the highest supported density - so if it only supports 4Mb chips and you feed it 16Mb chips, it shows up as if the module is 1/4 of its regular size.

Being detected as 1/2 of its size and then hanging the system sounds like either the SIMM is dead or there's some other compatibility issue going on.

Reply 5 of 14, by andromeda

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evasive wrote on 2021-03-31, 06:03:
We don't have that one listed in the database yet, would you post pictures of front and back + a bios dump in the 80486 bios thr […]
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We don't have that one listed in the database yet, would you post pictures of front and back + a bios dump in the 80486 bios thread please?
80486 BIOS image collection
It will be listed here:
http://www.win3x.org/uh19/motherboard/search

In the mean time I'll see if I have a manual somewhere that may answer your question about the maximum memory supported.

Take notice that EDO RAM support is flaky at best on boards this early, you have a better chance with FPM memory sticks.

Yes, EDO RAM not work on my motherboard but FPM work well.

https://imgur.com/ug905t7

https://imgur.com/a/RlOxqW2

https://imgur.com/Gp464Ub

amaquest AP8548 486 DX2-66 4 ISA 16 bit, 3 PCI rev 2.0 24Mb RAM
4x72pin FPM
Bios Award v4.50PG,
string bios: 11/30/95-SiS-496-497/A/B-2A4IBADBC-00
board/bios-version: AP8548 BIOS VER.D12 RELEASE 12/21/1995 UM8669
Chipset: SiS-496-497/A/B //SiS 496/497
PnP (ACFG,ESCD,DMI): PnP V1.0/ESCD
Computer ID: FC, SubTyp: 01, BIOS-Level : 0
Controller board : VIA VT82C42N
Voltage stabilization chips:
DC to DC: A1012; regulator-HA17393 (Harris IMHO)
COM Interface: ASP AP 232, 2 units

Last edited by andromeda on 2021-03-31, 12:34. Edited 2 times in total.

Reply 6 of 14, by andromeda

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dionb wrote on 2021-03-31, 06:05:
What kind of 32MB SIMMs are you trying? (number and type of chips) And are they known-good in a different system? Also you say " […]
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What kind of 32MB SIMMs are you trying? (number and type of chips) And are they known-good in a different system?
Also you say "strips" - have you tested with a single 32MB SIMM?

It's unlikely that the memory density is the cause of these problems; as a rule if memory is too large for the controller, it just addresses the chips with the highest supported density - so if it only supports 4Mb chips and you feed it 16Mb chips, it shows up as if the module is 1/4 of its regular size.

Being detected as 1/2 of its size and then hanging the system sounds like either the SIMM is dead or there's some other compatibility issue going on.

I tested with 32MB double-sided strips, 8 chips on each side, the brands that work in my motherboard are goldstar and texas instrument,
the others that do not work are from the NEC, LGS, MT, I 've not tested 16MB strips, except one, no name which does not work,
I have no other machine to test them, at the beginning the strips worked under dos, I had 72MB (2x32Mo + 2x4Mo), as soon as i installed win95 it never worked, only crashes under win95,
and it corrupted the disk with weird characters, i had to repartition and reformat each time.
there, it no longer works at all, black screen.
now i have 2x8Mo + 2x4Mo (24Mo), it work fine.
I would have to test with a 16Mo texas instrument strip, if it works, it would mean that the maximum ram is 64Mo if not , the maximum ram is 32Mo.

Reply 7 of 14, by dionb

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andromeda wrote on 2021-03-31, 12:11:

[...]

I tested with 32MB double-sided strips, 8 chips on each side, the brands that work in my motherboard are goldstar and texas instrument,
the others that do not work are from the NEC, LGS, MT, I 've not tested 16MB strips, except one, no name which does not work,

OK, but what's the actual chip code on the chips on these modules?

For LGS it might be something like: GM71C17400BT6 Or maybe GM71C17403BT6.

See, particularly the comments that Goldstar chips do work but LGS (=Lucky Goldstar) don't suggests the problem isn't with brand but with age (Goldstar changed their name very early on in the 72p SIMM era), and that makes me suspect that even though the motherboard chipset is supposed to support EDO, this motherboard might not do so (or might need some BIOS tweaks). That 0 or 3 above is the difference between FP and EDO. If you post the chip code for each of the SIMMs that do work and those of the SIMMs that don't, we could see soon enough what the common factors are.

I have no other machine to test them, at the beginning the strips worked under dos, I had 72MB (2x32Mo + 2x4Mo), as soon as i in […]
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I have no other machine to test them, at the beginning the strips worked under dos, I had 72MB (2x32Mo + 2x4Mo), as soon as i installed win95 it never worked, only crashes under win95,
and it corrupted the disk with weird characters, i had to repartition and reformat each time.
there, it no longer works at all, black screen.
now i have 2x8Mo + 2x4Mo (24Mo), it work fine.
I would have to test with a 16Mo texas instrument strip, if it works, it would mean that the maximum ram is 64Mo if not , the maximum ram is 32Mo.

You're changing far too many things at once. Test with *one* SIMM and see if that works. Then replace it with *one* other SIMM. Only after you're sure that both work separately, try to see if they work together. Take it one step at a time, then you know exactly which bit went wrong if it does fail.

What's suspicious here is that 72MB >64MB. This might be a cache / tag configuration issue. If so, a single 32MB SIMM would work fine. DOS hardly uses anything over 1MB, so no surprise that that wasn't affected like Win95.

There's one more option: memory bus loading. If you have the memory bus at full capacity, with at least 48 chips on it with that 72MB config, it might need looser timings than with less chips. Here again, one, two or three SIMMs likely wouldn't have problem.

So, go at it in a structured way to see if it's:
1) related to specific chip specs (i.e. doesn't like EDO, even one single SIMM of a certain type won't work)
2) related to total RAM size (i.e. single 32MB SIMM is fine but at some point it borks, most likely when you go over 64MB)
3) related to bus loading, so number of RAM chips regardless of size

Reply 8 of 14, by andromeda

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Here are the strips that are currently working (24Mo)

on SIMM1: GOLDSTAR 8Mo GM71C4400BJ-70 double side 16chip FPM
on SIMM2: TI TMS4400DJ-60 8M double side 16 chip FPM
on SIMM3 TI TMS44400DJ-60 4Mo single side 8 chip FPM
on SIMM4: NEC 424400-70 4Mo single side 8chip FPM

TOTAL 24Mo (All work fine)

Here are the strips that do not work

1) MT 4LC4M4E8DJ-6 32Mo double side 16 chip EDO
2) NEC 4217400-60 32Mo double side 16 chip FPM
3) LGS GM71C17400CJ6 32Mo double side 16 chip FPM
4) HY51164001J-60 (4123) 16Mo single side 8 chip FPM
5) SEC KM416C1204AJ-60 4Mo single side 2 chip EDO
6) HY5118164BJC-60 4Mo single side 2 chip EDO

At the beginning some strips below worked, after they did not work any more, black screen or memory failed.
I tested each bar that did not work, one by one on each bank (simm1 .. simm4)

Currently In the bios the settings are as follows which works with 24Mo

https://imgur.com/8kHSO5U

https://imgur.com/8SjvW4L

I have tested 2) 3) and 4) on SIMM1, SIMM2, SIMM3, it don't work (only FPM)
I have tested all 3 EDO 1), 5) and 6) on SIMM1, SIMM2, SIMM3 it don't work
I have tested 5) and 6) on SIMM1 and SIMM2, it don't work

Either the characteristics of these rams are not good for my motherboard or it is at the level of parameters at the bios level,
by default it is in automatic enable

I ordered a 16MB single-sided TMS strip, I'll see what it looks like within 10 days
these are the same characteristics as the TMS which works at the cache level (CBR)

Reply 9 of 14, by andromeda

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I have received my 16MB FPM SIMM 72p 4Mx32 60ns 5v no parity TMS417800DZ-60, single side 8 chip
it work but is only 8MB.
either it's a problem with my order and I was sent a strip of 8MB instead of 16MB or my motherboard does not support more than 16MB,
which will make a total of 32MB for my motherboard.

Any idea ?

Reply 10 of 14, by weedeewee

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andromeda wrote on 2021-04-08, 09:49:
I have received my 16MB FPM SIMM 72p 4Mx32 60ns 5v no parity TMS417800DZ-60, single side 8 chip it work but is only 8MB. either […]
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I have received my 16MB FPM SIMM 72p 4Mx32 60ns 5v no parity TMS417800DZ-60, single side 8 chip
it work but is only 8MB.
either it's a problem with my order and I was sent a strip of 8MB instead of 16MB or my motherboard does not support more than 16MB,
which will make a total of 32MB for my motherboard.

Any idea ?

TMS417800DZ-60 : 2097152-Word BY 8-BIT HIGH-SPEED DRAM
with 8 chips it is indeed a 16MB module.

highly likely that your motherboard or bios is being picky.

Reply 11 of 14, by andromeda

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yes surely it is difficult, the other ram sticks work very well, where can the problem come from? I put a screen on the parameters of the bios ram, maybe the problem comes from there.
I set to automatic, it may be necessary to manually adjust the parameters of the ram?

https://imgur.com/8kHSO5U

except that the 16MB memory stick is seen as 8MB, it works well for the moment and I have no crash problem with win95.

Reply 12 of 14, by weedeewee

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andromeda wrote on 2021-04-08, 10:30:
yes surely it is difficult, the other ram sticks work very well, where can the problem come from? I put a screen on the paramete […]
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yes surely it is difficult, the other ram sticks work very well, where can the problem come from? I put a screen on the parameters of the bios ram, maybe the problem comes from there.
I set to automatic, it may be necessary to manually adjust the parameters of the ram?

https://imgur.com/8kHSO5U

except that the 16MB memory stick is seen as 8MB, it works well for the moment and I have no crash problem with win95.

Memory timings can be adjusted.
Memory size is (almost) always autodetected by the bios.
Failure to detect can be either due to bios, mainboard or both.
YMMV

Reply 13 of 14, by andromeda

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It is possible or else my motherboard only allows 8MB ram strips and is limited to 32MB in total,
because 8MB strips work and are detected correctly.
But I'll never know, unless I have a program that can determine the maximum RAM size for a motherboard.

Reply 14 of 14, by evasive

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I think it can only handle low-density chips on memory sticks so a 16MB stick would need to have 8 chips at least and a 32MB stick would need to have 16 (8 on each side of the stick).

64MB FPM/EDO 72pin sticks with 32 chips do exist BTW.

Chipset limit is 256MB.