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386 RAM Installation Issue

V

VirusVox

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Joined
May 5, 2020
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45
Location
New Brunswick, Canada
Hey all!

I'm not sure if this is a hardware issue, or a memory management issue on my end (I've never set up RAM in MS-DOS 6.22), but today I installed 4 1MB SIMMS in my 386, which should bring the total RAM to 6MB. The RAM was purchased as tested and working, so if the listing is trustworthy and accurate I'm not sure what's happening here. When loading the computer sometimes it will detect 640K of conventional memory, and 2048K of Extended Memory. But for the most part it detects 640K Conventional, and then beeps a few times in a high pitched tone. After that I get 3 short beeps and DOS force-loads into DOS Low.

In my CONFIG.SYS I have it set to load in this order:

DEVICE=C:\DOS\SETVER.EXE
DEVICE=C:\DOS\HIMEM.SYS
DEVICE=C:\DOS\EMM386.EXE
DOS=HIGH,UMB
FILES=30

Am I making a simple memory management mistake, or is this more than likely something deeper, hardware related? There were no SIMMS installed when I got the PC, but I can tell there definitely have been in the past as a couple of the tabs on the SIMM slots are broken off. All SIMM slots still have at least one tab so the RAM is still seating correctly from what I can tell.

I also have the RAM installed in the two slots farthest away from the CPU, one empty slot, and then the next two slots. I was troubleshooting that specific empty slot as it seemed as soon as I put a stick in it, it forced it to load into DOS Low, but that could've just been coincidence as it's still doing it.

Any ideas?

Thanks!
 
What model of motherboard? Most of the 386 boards I know of had 8 30-pin SIMM sockets and needed a complete bank of 4 SIMMs to be filled in order to work. 5 slots seems unusual so I hope you can provide more information. Pictures might not hurt either.
 
There are, in fact, 8 RAM slots on the board, I've just been moving them around and testing them to see if that helps the situation at all. The mobo is a Biostar MB-1325P. This link takes you to an overview of the board - https://stason.org/TULARC/pc/mother...TECH-INTERNATIONAL-CORPORATION-386-MB-31.html

I have moved everything to the indicated Bank 2 on the link, and now it's showing the 2MB of on-board memory, and flagging a CMOS memory size mismatch. I had them installed in this configuration on my first attempt, and it resulted in the beeping memory problems I had, but now it's not doing that and just flagging this error.
 
Last edited:
That was what I was just checking now, and all modules are 1MB but I did notice something strange. One module populated with Siemens chips led to me an electronic database sheet, showing it as a 1Mx1-Bit low power module, whereas the others are 1Mx9 modules. Could that be what's causing it not to work properly?
 
VirusVox said:
That was what I was just checking now, and all modules are 1MB but I did notice something strange. One module populated with Siemens chips led to me an electronic database sheet, showing it as a 1Mx1-Bit low power module, whereas the others are 1Mx9 modules. Could that be what's causing it not to work properly?
Click to expand...

Try not to mix and match. It's okay to experiment but it's always best to stick within the specs, especially on the initial setup. I think you're on the right track.
 
krebizfan said:
What model of motherboard? Most of the 386 boards I know of had 8 30-pin SIMM sockets and needed a complete bank of 4 SIMMs to be filled in order to work. 5 slots seems unusual so I hope you can provide more information. Pictures might not hurt either.
Click to expand...

386DX processors need a minimum of four 30 pin SIMMs in a bank to make up the 32 bit bus. 386SX processors only need two 30 pin SIMMs because of the reduced 16 bit external data bus.

There are chipsets which can run in "gimp" mode down to just one or two 30 pin SIMMs, but performance is obviously severely crippled. This "feature" was more common on retail systems so the manufacturer could save money on expensive memory.
 
Agent Orange said:
Try not to mix and match. It's okay to experiment but it's always best to stick within the specs, especially on the initial setup. I think you're on the right track.
Click to expand...

I don't actually have any other 30-pin SIMMS at the moment. I'll buy a matching set and try those when they arrive, and continue trying to troubleshoot these while I wait.
 
Okay, update on all of this:

I now have 8 identical 30-pin SIMMS, all 1 MB in size, installed in my 386 and nothing has changed. It still loads to 640K and then beeps in a high-pitched tone, tells me I have a CMOS Memory Size Mismatch, and then it loads into DOS with just 640K of memory. Is there something I'm doing wrong?

The only part of my CONFIG.SYS that has changed is during installation of my SB16 (which went off without a hitch) it changed FILES from 30 to 40. Everything else is still identical to what was indicated in the first post.
 
VirusVox said:
What's the difference, if I might ask? I only have 1 9-chip SIMM and I've bought two lots of them already. The SIMMS installed now are 3 chip, listed as 1Mx9
Click to expand...

Many older boards will not properly refresh the 3 chip SIMMs. The refresh timing for the 9 chips is different
 
A little over a year later, an update!

Turns out I'm just a bit of an idiot. 2+8 in SIMMS is not a supported RAM configuration on this motherboard. I removed the 2MB worth of socketed RAM chips and installed 8MB worth of SIMMS and the PC now correctly detects all 8MB of RAM!
 
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