If you're sure that it is capped at 64MB in Win98 in addition to DOS mode (where a 64MB max is no surprise), it's possible that your BIOS only supports INT 15H AH=88H to determine the amount of memory, which has a 64MB max. There is a newer variant INT 15H AX=E801H, but perhaps your BIOS doesn't support it, so Win98 sees only 64MB. 128MB is an astoundingly high amount of memory for 01/11/95, and it's possible the Award "core" for your BIOS is even older.

jakethompson1 wrote on 2023-11-11, 22:40:

If you're sure that it is capped at 64MB in Win98 in addition to DOS mode (where a 64MB max is no surprise), it's possible that your BIOS only supports INT 15H AH=88H to determine the amount of memory, which has a 64MB max. There is a newer variant INT 15H AX=E801H, but perhaps your BIOS doesn't support it, so Win98 sees only 64MB. 128MB is an astoundingly high amount of memory for 01/11/95, and it's possible the Award "core" for your BIOS is even older.

I see, but if the bios didn't support it (INT 15H AX=E801H), why would it show and test it correctly before booting the OS? Also, the board is supposed to accept up to 128 mb according the the documentation. Of course, 128 megs is overkill for what I need, but it would still be nice to max the board out.

In general, I found this board to be pretty buggy overall with unstable ide/fdd controllers, fiddly cache timings and a supposedly error-prone Dallas RTC-clone. My next desperate attempt will be to get a new RTC battery (CR1220, not something I have in stock) for it. Seems trivial and it was replaced pretty recently, but I read that it could run low within a year already, causing all kinds of instabilities. But I am really not very confident that this will change anything for my ram problem.

By the way, I am sure that it's limited in Win98 as well and I verified that the corresponding setting in msconfig is OFF.

Since your config screen shows drive A: as 1.2mb and no 1.44mb, I suspect your cmos battery is indeed dead as that doesn't sound a suitable configuration for a Socket 4.

Boot into "safe mode command prompt only" (no himem.sys)
Run DEBUG:
-r ax
AX ????
:e801
-a
????:0100 int 15
????:0102 int 3
????:0103
-g

You will either get NC (no error) or CY (error) at the end of the last line. If you get CY then E801 isn't supported even if the chipset portion of the bios supports more than 64MB, so there is no way to report >64MB to the OS. Linux could be used on such systems by overriding the bios with a mem= parameter. If you get NC then you can interpret AX/BX/CX/DX (in hex) as given here: http://www.ctyme.com/intr/rb-1739.htm

Nice jake !
Win98 has a 512Mb limit (unmodded) so do not think it a Win98 thing. The ECS SI54P AIO has same chipset and looks near identical but has BIOS thru late 1995 where yours in 1994 so most likely a bios issue.

Here is far more detailed info from os2museum https://www.os2museum.com/wp/windows-nt-3-1-a … mory-detection/

jakethompson1 wrote on 2023-11-12, 02:28:

Here is far more detailed info from os2museum https://www.os2museum.com/wp/windows-nt-3-1-a … mory-detection/

Ahh interesting, edit: have seen the OS2 64MB enable in bios and did not quite understand it, and that was later unneeded. It is all about the int15 usage 😀

What kind of ram are you using
EDO/FPM 60ns/70ns?

Is it all matching?

I would tend to view this as either some type of board damage or ram compatibility limitations

Very old SIS boards for me at least were very strange in what modules would work and would not, sometimes 4 of a kind failed

jakethompson1 wrote on 2023-11-12, 02:18:

Since your config screen shows drive A: as 1.2mb and no 1.44mb, I suspect your cmos battery is indeed dead as that doesn't sound […]
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Since your config screen shows drive A: as 1.2mb and no 1.44mb, I suspect your cmos battery is indeed dead as that doesn't sound a suitable configuration for a Socket 4.

Boot into "safe mode command prompt only" (no himem.sys)
Run DEBUG:
-r ax
AX ????
:e801
-a
????:0100 int 15
????:0102 int 3
????:0103
-g

You will either get NC (no error) or CY (error) at the end of the last line. If you get CY then E801 isn't supported even if the chipset portion of the bios supports more than 64MB, so there is no way to report >64MB to the OS. Linux could be used on such systems by overriding the bios with a mem= parameter. If you get NC then you can interpret AX/BX/CX/DX (in hex) as given here: http://www.ctyme.com/intr/rb-1739.htm

Thank you for the detailed instructions!

I am indeed getting CY at the end of the last line.

I guess that's also the end of the line for this issue... I suppose there is no equivalent overriding parameter for DOS or Win98 (of course, there is no >64 MB option in the BIOS, not even in modbin)?