That's... unexpected.

Not that an ancient PSU would be flakey - but the symptoms aren't ones I've ever seen. Good heads-up not to make assumptions, I might re-check some obscure issues here too.

Isn’t it strange? Growing up I remember having to replace failing PSUs but they’d normally do something more… obvious. Open and close the CD drive over and over, known working drives just aren’t recognized, etc, but nothing like this. I guess it had just enough juice to power the system up, but any kind of strain caused it to putter out. Regardless, I’m happy it worked, and Windows 95 was a mistake. I’ll have to post some pictures here soon. Running Windows 3.11 like a dream on a DX-33! Now it’s time to source more RAM and a faster processor…

Alright! She's up and running with Windows 3.11! I figured I'd show some pictures and ask a few questions now that it's up and running.

I've included shots of everything I think is pertinent! An overview of the system, the front, a shot of the chipset, both CPU's and RAM, and the jumper configuration.

So a few questions. In DOS, I can't really seem to run any games. I'm out of memory, and adding EMM386.exe from config.sys throws an error that it's not installed.

This computer came shipped with the OTI-077 video chipset, which surprisingly already had the 512k expansion added to the motherboard for a full 1meg of video RAM. Still, it's egregiously slow at 800x600. Flying Windows screensaver is probably running at a frame or two a second. Is this normal? I've installed the drivers from OAK OTI-77 driver diskette.

I suppose that's all I have for now! I know it's not much, but I love this little thing.

Oh, I forgot to add, this PC can handle up to 20megs of RAM (currently at 8MB), what kind of sticks should I look into? Also, with those jumper settings and that chipset in mind, what would be the most feasible processor upgrade? Would be pretty neat to get DOOM running at an acceptable framerate.

That pic shows 4x 30p SIMMs. That suggests you have the version of the board with 4MB onboard and 4x 1MB SIMM. The - only - upgrade you could do would be to 4x 4MB SIMMs (30p SIMMs need to be placed in fours in a 486). Specs don't say anything about parity but the ones you have have it (3 chips instead of 2 per SIMM) so it might be safe to look for parity. Fortunately the vast majority of 30p SIMMs are parity. Some boards are picky about 3 chips vs 9 chips, but for 4MB you're almost certainly going to need 9-chip SIMMs. Finally you need at least 80ns DRAM (lower is better)

One thing you don't need to worry about is FP vs EDO - 30p SIMMs are all FP, despite what clueless eBay sellers are saying (who assume "SIMM = eBay"). If in doubt, get a pic that shows the individual chips and look up the datasheets. FP datasheets frequently don't mention "Fast Page Mode", but EDO always do mention "Extended Data Out", so no EDO is no EDO 😉

But...

Your memory issus have nothing to do with 8MB not being enough. There are basically no DOS games - not even later ones that would run like a slug on a 486-33 - that can use more than 8MB. The only reason for upgrade is Win3.x performance (and there you do notice the difference between 8MB and 16MB).

Your problem is DOS memory configuration; reading the error you either don't have EMM386.EXE on the system or (more likely) the line in your CONFIG.SYS is pointing to the wrong place. Post your CONFIG.SYS here and say which directory EMM386.EXE is in and we should be able to see what's up.

Ah, I see! I see one pair of 4x4meg 3 chip 30pin 70ns SIMM modules on ebay, I might have to grab those on payday and see how it takes. I also noted that I have the plastic RAM slots that are the chagrin of many retro enthusiasts as they tend to snap, but of course I do, it's a Packard Bell.

Here's a copy of the current AUTOEXEC.BAT i'm running after removing some of the Creative Mixer bloatware which I thought was leading me to the memory errors

1set ieppp=C:\
2set pctcp=C:\pctcp.shv
3SET SOUND=C:\SB16
4SET BLASTER=A220 I5 D1 H5 P330 E620 T6
5C:\WINDOWS\SMARTDRV.EXE /L
6PATH C:\;C:\WINDOWS
7SET TEMP=C:\WINDOWS\TEMP
8LOADHIGH=C:\DOS\MSCDEX.EXE /D:MSCD001 /E 

here's the original, backed up AUTOEXEC.BAT just in case I broke anything

1set ieppp=C:\
2set pctcp=C:\pctcp.shv
3SET SOUND=C:\SB16
4SET BLASTER=A220 I5 D1 H5 P330 E620 T6
5SET MIDI=SYNTH:1 MAP:E MODE:0
6SET CTCM=C:\SB16
7C:\SB16\DIAGNOSE /S /W=C:\WINDOWS
8C:\SB16\AWEUTIL /S
9C:\SB16\MIXERSET /P /Q
10C:\SB16\CTCU.EXE /S /W=C:\WINDOWS
11C:\WINDOWS\SMARTDRV.EXE /L
12PATH C:\;C:\WINDOWS
13SET TEMP=C:\WINDOWS\TEMP
14LOADHIGH=C:\DOS\MSCDEX.EXE /D:MSCD001

and finally, if it can be of any use, my config.sys file

1DEVICEHIGH=C:\WINDOWS\EMM386.EXE RAM I=B000-B7FF
2DEVICE=C:\SB16\CTCM.EXE
3FILES=30
4BUFFERS=30
5DEVICE=C:\WINDOWS\HIMEM.SYS
6DEVICE=C:\WINDOWS\SMARTDRV.EXE /DOUBLE_BUFFER
7DEVICE=C:\WINDOWS\IFSHLP.SYS
8STACKS=9,256
9DEVICEHIGH=C:\DOS\OAKCDROM.SYS /D:MSCD001 
10FILES=40

Alright! I went through and reinstalled DOS 6.22. Everything is working as it should! A few games are complaining about memory, but only after I've loaded/closed a few other games. Reboots seem to help.

I also tried FastDOOM. Seeing others run it on a DX-33, it seems like I should be getting much better results. I've heard Oak Technology VGA chipsets are slow, but this is really slow. I guess I'm going to look into a SpeedStar 64 to see if I can't add any umph.

Would you recommend any CPU upgrade? I suppose with those jumpers and that chipset, I'm just not sure how high I could go. I doubt an AMD DX-5 would be very happy in there, seeing as the board apparently only supports 5v.

My PB is a different model but I think it's from a similar era(PB410A mobo), and it has issues with utilizing cache. I'm not sure if yours would be the same, but it does mean that my system will always under-perform. I upgraded from a 25MHz to 50Mhz chip and certainly saw an improvement, but it will always be behind the curve compared to a system with fully working cache.

I also tried an AM5x86 in it with the proper interposer for the voltage, and my system wasn't happy with it. I can't remember exactly what the issues were, but I think it was general instability. Since our systems are different I wouldn't necessarily say you can't push it that far, but I wouldn't pin my hopes on being able to do it.

Ah, I'm going to look a bit more into how it's utilizing the cache on the board, thank you. Under-performing is okay, I just want to see this computer in its peak shape, even if it does lag behind the rest. It was my first computer, so I'd love to give it everything I can.

I've found a 486SocketBlaster on PCBWay, adding that to the list of potential upgrades I'm going to buy for this. It's worth a shot, and if the board doesn't like it, I'll always have my DX-33. I'll report back with my findings, of course. Thank you for your insight.

SufferWell1396 wrote on 2025-02-09, 16:51:

Ah, I see! I see one pair of 4x4meg 3 chip 30pin 70ns SIMM modules on ebay, I might have to grab those on payday and see how it […]
Show full quote

Ah, I see! I see one pair of 4x4meg 3 chip 30pin 70ns SIMM modules on ebay, I might have to grab those on payday and see how it takes. I also noted that I have the plastic RAM slots that are the chagrin of many retro enthusiasts as they tend to snap, but of course I do, it's a Packard Bell.

Here's a copy of the current AUTOEXEC.BAT i'm running after removing some of the Creative Mixer bloatware which I thought was leading me to the memory errors

Copy code to clipboard

1set ieppp=C:\
2set pctcp=C:\pctcp.shv
3SET SOUND=C:\SB16
4SET BLASTER=A220 I5 D1 H5 P330 E620 T6
5C:\WINDOWS\SMARTDRV.EXE /L
6PATH C:\;C:\WINDOWS
7SET TEMP=C:\WINDOWS\TEMP
8LOADHIGH=C:\DOS\MSCDEX.EXE /D:MSCD001 /E 

here's the original, backed up AUTOEXEC.BAT just in case I broke anything

Copy code to clipboard

1set ieppp=C:\
2set pctcp=C:\pctcp.shv
3SET SOUND=C:\SB16
4SET BLASTER=A220 I5 D1 H5 P330 E620 T6
5SET MIDI=SYNTH:1 MAP:E MODE:0
6SET CTCM=C:\SB16
7C:\SB16\DIAGNOSE /S /W=C:\WINDOWS
8C:\SB16\AWEUTIL /S
9C:\SB16\MIXERSET /P /Q
10C:\SB16\CTCU.EXE /S /W=C:\WINDOWS
11C:\WINDOWS\SMARTDRV.EXE /L
12PATH C:\;C:\WINDOWS
13SET TEMP=C:\WINDOWS\TEMP
14LOADHIGH=C:\DOS\MSCDEX.EXE /D:MSCD001

and finally, if it can be of any use, my config.sys file

Copy code to clipboard

1DEVICEHIGH=C:\WINDOWS\EMM386.EXE RAM I=B000-B7FF
2DEVICE=C:\SB16\CTCM.EXE
3FILES=30
4BUFFERS=30
5DEVICE=C:\WINDOWS\HIMEM.SYS
6DEVICE=C:\WINDOWS\SMARTDRV.EXE /DOUBLE_BUFFER
7DEVICE=C:\WINDOWS\IFSHLP.SYS
8STACKS=9,256
9DEVICEHIGH=C:\DOS\OAKCDROM.SYS /D:MSCD001 
10FILES=40

To be sure I'd have to see the output of MEM /C/P, but looking at this you have at least three big conventional memory no-nos in CONFIG.SYS

CONFIG.SYS:
- CTCM.EXE doesn't need to be in CONFIG.SYS, better to call it in AUTOEXEC.BAT
- HIMEM.SYS should be called first of all
- if you want to free up conventional memory, load DOS high and do it before EMM386 with: DOS=HIGH,UMB
- EMM386.EXE should be called immediately after that
- FILES & BUFFERS look OK
- SMARTDRV.EXE eats RAM and should be loaded high if used at all. You're also calling it in both CONFIG.SYS and AUTOEXEC.BAT. Do the latter only.
- IFSHLP.SYS is only needed if you're running Windows, if not, save yourself some RAM here
- STACKS looks OK
- OAKCDROM.SYS looks OK
- You alreay called files earlier on. Want 40? Make it 40 once.

So I would do:

1DEVICE=C:\WINDOWS\HIMEM.SYS
2DOS=HIGH,UMB
3DEVICEHIGH=C:\WINDOWS\EMM386.EXE RAM I=B000-B7FF
4FILES=40
5BUFFERS=30
6STACKS=9,256
7DEVICEHIGH=C:\DOS\OAKCDROM.SYS /D:MSCD001 

Then AUTOEXEC.BAT:
set iepp & pctcp: can't do any harm (just setting environment variables), but why? Unless you need these, leave out
SET SOUND & BLASTER - looking good if parameters are correct
CTCM.EXE can be called here. It's not a TSR, just an init program that terminates after use, so no need to load high. Same goes for DIAGNOSE
Leaving out AWEUTIL saves memory, but kills the EMU8k synth chip that's the main reason for using an AWE card. This one's complicated though as it really eats RAM and protected mode games (like Doom...) won't work with it active, but most non-protected mode games won't be able to use its wavetable without AWEUTIL. If anything, this is a good reason to make a DOS boot menu and choose options with and without it.
It's better to load MSCDEX before SMARTRV (if you really want the latter in the first place), and to try to load both high.

So my suggestion:

1SET SOUND=C:\SB16
2SET BLASTER=A220 I5 D1 H5 P330 E620 T6
3SET MIDI=SYNTH:1 MAP:E MODE:0
4SET CTCM=C:\SB16
5C:\SB16\CTCM.EXE
6C:\SB16\DIAGNOSE /S /W=C:\WINDOWS
7REM LH C:\SB16\AWEUTIL /S
8LH=C:\DOS\MSCDEX.EXE /D:MSCD001
9PATH C:\;C:\WINDOWS
10SET TEMP=C:\WINDOWS\TEMP
11REM LH C:\WINDOWS\SMARTDRV.EXE

At a guess this will save you about 100kB of conventional memory and solve your problems with games complaining about memory usage.

You could win more by tweaking which things are loaded high in which order. Also, there are more lightweight alternatives for OAKCDROM.SYS, MSCDEX.ECE, SMARTDRV.EXE and smarter alternatives for EMM386.EXE to play around with, but they're another set of DOS rabbit holes to dive down only if you are obsessed with conventional memory.

Oh, and no mouse driver?

Perfect! Thank you so much for your help! I have those settings loaded and she's flying. I loaded CTMOUSE as soon as you brought it up, I had forgotten that DOOM had been complaining about the lack of a mouse driver.

Anything else you'd recommend? I'm looking at prices of parts and good lord, things are expensive. I'll probably end up getting them, but maybe ebay isn't the best place to look... Do you have any recommendations?

Thing to remember about eBay is that the prices you see when you randomly search are precisely the ones no-one was prepared to pay. Really good deals crop up on eBay all the time, but are snapped up just as quickly. If you want something that isn't cheap, set up an alert for a search term so you get a heads-up as soon as one pops up. Chances are it will be a lot less expensive than the price nobody wanted to pay.

But unless you want to start exploring all the wild wonderful DOS sound options, the only suggestion I'd make is to add a network card for file transfer (via FTP, run the MTCP server on this old thing, use a modern client like Filezilla on your modern machine). If you want an easy to find and easy to get running option, 3Com's 3C509B is a safe bet. That said, I've just installed an SMC 8416 card in my most recent DOS box and found it just as easy. Intel and AMD cards (yes, both made ISA NICs) are fine too, as are DEC and even Realtek and UMC options. In fact, you can usually get pretty much anything with an RJ45 working and for the purposes of file sharing under DOS, performance differences aren't that relevant. Just make sure it is an Ethernet card and not ISDN or Token Ring.