Need help figuring out what I can do/upgrade on an old 486 I was gifted
Posted by dametreus@reddit | vintagecomputing | View on Reddit | 66 comments
To make a long story short im now in possession of a 486 PC from about 1992 if my research is correct. Its a Zeos machine that according to the previous owner was used for CAD in the early 90s? I wanna use it to play some DOS and early Windows 95 games but im not exactly sure what im able to upgrade on this system.
Right now it seems to have the following hardware installed
- A Zeos motherboard (This is also a Zeos system if that helps)
- An Intel i486 DX 50MHz
- An unknown amount of ram
- No L2 Cache
- A Diamond Speedstar 24 (Which from what ive been able to gather is a really good ISA 2D video card? So ill probably leave that as is seeing as I dont have PCI or VLB)
I wanna upgrade it to be closer to something around 1994-1995 in hopes that it might be able to play Duke Nukem 3D and possibly Quake? But im not sure what if anything are drop in replacements.
I was thinking about putting in
- A Cyrix 5x86 or Pentium Overdrive (Seems like a drop in replacement for this 486???)
- A Soundblaster Awe-32 or Soundblaster pro 2.0
- Some amount of L2 Cache
- and a Roland Mpu-401 compatible card to use with an MT-32 or something
Not sure how much of this is possible but thats why I figured id ask here since you guys probably have more knowledge about this than I do
carcenomy@reddit
The DX50 is a pretty neat thing, they were premium fanciness back in the day for CAD before the DX2 arrived.
The no VLB thing is a blessing in disguise for this system; it's running the bus at 50MHz, cards would scream in terror.
This is almost certainly the same reason it doesn't have the unique cache upgrade, they were usually rated for 25MHz and 33MHz not 50MHz.
Basically treat it like a very aggressive 386. Chuck in an SB16 or something and enjoy it, it'll never quite be the angry Doom/Duke/Quake system but it's a very unique slice of history from a very specific point in time.
NightmareJoker2@reddit
There are few cards that accept a 50MHz bus, but the VLB Cirrus Logic and Tseng cards all do. The same is true of most EISA cards.
My EISA+VLB 486DX-50 has an S3 86C805, I think, that even has jumper settings for it.
The 50MHz bus speed is more advantageous for server workloads than the faster CPU core speeds of the clock doubled ones, because the faster bus means faster uncached memory access times, and better I/O latencies and throughput for things like SCSI and Ethernet controllers. A 50MHz bus means faster file transfers, and can be the difference of several megabytes per second. To put that in context, a 3com 100Mbps Ethernet card is I/O limited by the 32-bit EISA bus to ~30-40Mbps, at 50MHz it can be almost 60Mbps. Unfortunately the Adaptec 32-bit EISA SCSI controllers are all slower than the 16-bit ISA ones (most of which aren’t stable at 50MHz), but at 50MHz they too are faster than any SCSI controller at 33MHz.
Also, Duke Nukem 1 and 2 run fine on my 50MHz 486DX, Duke Nukem 3D I haven’t tried, it’s not really my style. I suppose I can install it and report back.
carcenomy@reddit
Oh yeah DN1 and DN2 would be smooth as glass, DN3D is a very different animal though!
Super keen to hear more about your machine though, these DX50s coming out of the woodwork is amazing
NightmareJoker2@reddit
I accidentally tested at 16MHz first, because I didn’t realize the turbo button was pressed, and it stuttered a lot… 😅
But at 50MHz, “standard” mode works okay even with the graphics on high. It’s only 320x200, but at the SVGA VESA modes, of which the game supports up to 800x600, they all stutter, even in the menu.
A 50MHz can totally play Duke 3D with all the sound options and graphics stuff turned on.
docshipley@reddit
I actually have a VLB system running a DX50. I'll admit it took a lot of mixing and matching to get a pair of VLB boards that'll run on that bus and run stable, but it screams. Diamond S3 video and a Promise I/O card.
Totally agree about preserving this one as is (although I'd sneak some reliable storage in there). It's a great find.
techika@reddit
Vlb system has fsb and multiply corection jumpers for overclock. Vlb video card are 2x faster tha isa. Vlb i/o has 32 bit controler , isa are only 16 bit
canthearu_ack@reddit
VLB is actually multiple times faster.
ISA is a 16bit bus running at best 16mhz (stock is 8mhz, so 16mhz ISA is quite an overclock in of itself)
VLB is a 32bit bus running at generally a minimum of 33mhz. (If you had a 486 at 25mhz, well yeah, VLB was running at 25mhz then)
So typically minimum of 4 times difference, usually somewhat more, as I reckon most people weren't able to flog their ISA bus quite that hard.
That said, a lot of contemporary graphics chipsets only had a 16bit interface to the local bus, which means that they were only getting half the maximum performance out of the VLB bus. This often didn't matter a lot, as a 32 bit VLB interface wouldn't be any faster than a 16bit VLB interface unless your code did 32bit reads and writes.
techika@reddit
Top answer, thanks for lection.
canthearu_ack@reddit
I second this. This is a very neat system. I would most definitely have it in my fleet. But it wouldn't be my doom system!
Kitchen_Part_882@reddit
Doom (and Doom2) ran fine on my SX 25 when I overclocked the CPU to 40MHz (I had a friend who played on a 386DX at quarter resolutionor less while I ran one step down from max screen size).
I did have VLB graphics, VLB disk controller (multi i/o card) and a bunch of cache chips I liberated from a dead motherboard, along with 16MB of RAM though.
Quake is definitely a no though - needs a Pentium to be anything but a slideshow (and, depending on taste, a pair of Voodoo2 cards for the visuals).
canthearu_ack@reddit
As mentioned in my other post, VLB makes a huge difference.
DrNick42@reddit
This
GGigabiteM@reddit
It'll play Doom. Duke 3D will also work if you lower the resolution and reduce the sound quality and number of effects.
carcenomy@reddit
I feel like you're gonna have a pretty sub optimal experience with the ET4000 in Build engine stuff...
This feels like something I should try for science.
GGigabiteM@reddit
It's not going to be a speed demon, but it will run. The ET4000AX was one of the better ISA video chips.
Now if it were an OAK video chipset... yeah that would be a very bad time.
carcenomy@reddit
I can probably test this, my 486 has dead L2 cache at the moment just like OPs machine, I could whip the Speedstar out of my 386... close enough for government work to see how it would do 😀
LSD_Ninja@reddit
I’m painfully aware of just how fickle the DX-50 was in a VLB system because I blew up a motherboard trying to troubleshoot it.
DisastrousLadder4472@reddit
Yeah, the DX-50 is a relatively rare 486 and was really pushing the limits of the tech at the time. It was quickly succeeded by the DX2-50 and DX2-66, I think. Keep it “stock”, IMO :)
RedditWishIHadnt@reddit
There’s no CPU cooling. Get a fan on that gent and it will do 80Mhz reliably (based on my own experiments 30 years ago).
NoctisBE@reddit
I'd honestly keep the DX50. Maybe throw in a PicoMEM (or PicoGUS if you prefer spinning rust), that way you have a decent sound card. Duke3D should run if you lower the screen size, and Doom should run just fine. Also, there's plenty of awesome games that run just fine on that machine.
canthearu_ack@reddit
This really isn't a good Doom/Duke3d/Quake system. The processor isn't too bad for Doom, but too slow from Duke3d and Quake.
But the biggest problem is that this system is not really good at pushing pixels, as it only has an ISA bus. Realistically, the full screen 3d games do better with a VLB or PCI systems, which can push a lot more pixels per second from the processor to the graphics card.
That said, most games up to Doom should perform well. The ET4000AX chip is generally high performance and mostly well tolerated by LCD screens.
Without a faster bus, this system will never be worth upgrading the CPU in. Nor will it be worth trying to track down whatever this thing used for L2 cache.
Get yourself a PicoGUS, maybe even get 2. This will look after pretty much all your sound, MPU-401, input and CDROM needs.
If you want a faster system for use with quake/doom/duke3d, perhaps pick yourself up a Pentium system. It will be far far cheaper, and much faster in the end, then anything you can do with this system.
lweinmunson@reddit
Duke3d should run on anything that can handle doom. I had a 486sx33 and we played a lot of network Duke in college. The engine was a little more advanced, but nothing truly 3d yet.
crmb_266@reddit
Are you sure ? I had a 486sx33 and Doom was ok (except le last levels) but Duke3D was running slow-mo except the smallest screen size maybe. I was only able to play with Build (the map editor)
lweinmunson@reddit
Yep. That 486 carried me through at least around '95 with 4MB of RAM. I don't remember if we had to change the resolution or even if that was an option with Duke3d, but we all had 486 systems with some form of VESA cards. I don't think any of us at the time noticed frame rate problems, and if we did, we just lived with it.
canthearu_ack@reddit
Eh, you can get duke3d to start up and run on reasonably low end machines.
A 486DX-40 with VLB Graphics card did ok with Duke3D, as that is what I originally played it on, but it wasn't that great an experience objectively. Given that you can get much better DOS hardware for not a lot of money, there is no real reason to put up with sloppy game performance!
Remember that we struggled through games playing bad because there really wasn't much other choice. That upgrade to make Duke3d run well was multiple thousands of dollars, and we were poor people back then!
And another thing, I shall again empathise that the OP isn't able to run VLB graphics cards in his system. This makes a really big difference for these kinds of games. Each frame takes a lot longer to move from the processor to the frame buffer when that frame buffer is on the ISA bus, starving the CPU of cycles needed to do the 3d perspective rendering. Don't forget that the 486 and Pentium were in-order execution engines. The entire pipeline stalls while the memory writes are taking place.
Altruistic_Lock_5362@reddit
The memories , this looks more like an office only machine. 50 mhz. My first compaq, was a 90mhz, my first taste of processing power in a home. My wife worked for Seagate tech. So I was able to buy ram and HD for almost nothing. And yes, Doom was a fun as hell game that was so addicting.
techika@reddit
https://theretroweb.com/motherboards/s/zeos-upgradable-systems-mainboard
Is look likes 386 mainboasd upgradet to support 486 dx
songoffall@reddit
Congrats on a lovely acquisition. Just from the get go, forget about Quake with a 486. To play Quake comfortably in software mode you would need at least a Pentium MMX or even better - a Pentium II
You might want to check the voltage limitations of your board before you put CPUs in it. Putting a 3.3v 486 in a 5v board is a recipe for a disaster.
I would also say it's a pretty early 486 board because of no VLB and no PCI. So have realistic expectations of your graphics too.
256k cache is good, also put in the TagRAM chip if you can. Don't go overboard with the RAM, as soon as you get above the cacheable amount it will start creating problems. Cache above 256k on your PC will do almost nothing.
As for SoundBlaster AWE32 vs SoundBlaster Pro 2.0 - put whatever you want in it. I'd say the AWE mode is nice as long as the games support it. But the OPL sound is more authentic on Pro 2.0. And an MT-32 makes the AWE mode redundant. But it will cost you. Another card I'd highly recommend, while not entirely period-correct (1995-1996) is ESS AudioDrive ES1868/1869. Might be the best ISA general purpose sound card, and if you get one with a WaveBlaster header, you get ESFM, which is as good or better than OPL, MPU401 in UART mode, WaveBlaster, SoundBlaster Pro 2.0 mode - all on one card with great compatibility and no need for TSR drivers.
The most important thing is, it's a period piece, you don't need to fall into the trap of trying to make it the fastest 486 possible, but you can make it a nice 1991 PC. Even if you put the most expensive high performance parts on it, you'll find out there's so many bottlenecks that your parts no longer make sense. It is better to go with a Cirrus Logic CL-GD5402 graphics card than the allegedly fastest ISA card Tseng ET4000 as I learned from my experience - WinG games on Windows 3.11 and even WinG SDK demos just crashed with it. I think you can still get CL-GD5402 for $50 on Ebay and even cheaper elsewhere. High compatibility is your friend here even more than performance.
It should run Doom and Duke3d comfortably, but I'd say mid to late era 2d DOS/Windows 3.11 games is where it will shine most.
lweinmunson@reddit
My first PC was a Zeos, and I'm not surprised that they managed to get a DX50 in there. One of the selling points on my 486 was that they used 52ns RAM speeds instead of the 70ns that was common at the time.
chandleya@reddit
I strongly advise against CPU in place upgrades. That’s actually a special machine. It’s capable of dual CPUs if you can source the riser.
https://theretroweb.com/motherboard/manual/32412.pdf
It also supports zeos hella proprietary 256KB fast cache daughter board
dnabre@reddit
Ever since one came through my high school computer club's donated equipment (we fix, tweaked, and updated them for the school), a dual 486 has been on my bucket list (right beside the dual 68K).
chandleya@reddit
Probably more likely to source a Ps/2 90 for that but yeah, top tier goal.
dnabre@reddit
Realistically I'm not expecting to ever get my hands one, but one can dream, right?
bio4m@reddit
AWE-32's are rare. Most cards sold as AWE-32's are actually SB32's
Personally I have a Creative Vibra 16 in my build (has a low output noise floor and a real OPL3 chip)
MPU-401 cards from Roland are crazy expensive. You can get support on most Sound Blasters but beware the hanging note bug
The PicoGUS is a phenomenal alternative
MT-32's are crazy expensive as well, look into MT32Pi as a modern alternative
ZarK-eh@reddit
For Roland, I went and build a few HardMPU's (PickledDog on github) and some MT32-Pi's. Maybe even consider https://pcmidi.eu with mpu-401's...
carcenomy@reddit
Preach! The PicoGUS even if you're not using it as a GUS clone is worth its weight for the intelligent mode MPU401 support alone.
Distribution-Radiant@reddit
I'd start with hooking up the hard drive. ;)
But the DX-50 wasn't a very common CPU, and should make that thing fly. Those were $$$$ back in the day.
LSD_Ninja@reddit
One of the reasons why the DX-50 isn’t terribly common is that the 50MHz bus speed doesn’t play nice with VLB.
tes_kitty@reddit
It should also get a heatsink. Running a 486DX-50 without one is not a good idea.
royalfarris@reddit
Dont' bother with any other cpu, that one is plentiful. This is the highest bus speed of any cpu of the era, and in many instances faster than the DX2xx series.
A soundblaster of any type is absolutely something you want.
A network card as well would make life easier.
If you can find an L2 cache, go for it. But few people had them.
Then you can see what type of extras you can find. You've got a lot of slots there to plug in neat stuff.
Der_Unbequeme@reddit
there is no upgrade for this thing, unless you get the Turbo Cache Module.
Best upgrade is an other main board for this cpu.
a i486-50 need a heatsink,
you can change the CPU with a DX/2-80, but you must change the oscillator crystal with a 40mhz one.
Objective-Ad3943@reddit
I’d like to see a good photo of the graphics card.
roanish@reddit
Do nothing, play commander keen.
docshipley@reddit
Remember that the processor is configured by jumpers, not BIOS settings. It's likely that you're stuck with a DX, as opposed to DX2, CPU.
My memory is foggy, but I think that weird header/socket next to the CPU is for Zeos' proprietary cache module. Good luck with that.
If you want a serious period gaming system you would need VLB video and at least 128kB cache, IOW a whole different motherboard, but what you have there is a very solid workstation. The DX50 is no slouch and it's a good video card. I would slap a decent sound card in it, trade all the hard drives for Compact Flash adapters and add a FlashFloppy "drive".
carcenomy@reddit
Sir... you raise more questions than answers with that last sentence - Duke ran great on a Pentium 100 with a 1MB Trio64V+, unless you were trying to run it in whacky VESA modes it would run superb on a 166 with a 4MB card.
AppropriateCap8891@reddit
But the 50 MHz bus and no wait states actually puts those past a DX-2, and as fast or faster than many DX-4s. The slower bus speeds and doubling-tripling wait states tended to really hamper the performance of those processors.
The optimal solution would be to look for one of the DX-4 100 chips that would work at 50 MHz. Those did give a boost, as it worked at the max bus speed and only doubled waits and not triple.
docshipley@reddit
Life I said, the DX-50 is no slouch.
Given the limitations of what OP has, though, and that it's essentially an all-original OEM workstation, I don't think trying to soup it up is the best answer.
GGigabiteM@reddit
The Pentium Overdrive will never work in this system, it requires Socket 3, which has 238 pins, vs the 169 pins of Socket 1 and 2.
Likewise, the Cyrix 5x86 will also not work in this system because of the 50 MHz bus speed and because they require a lower core voltage than 5 volts.
The core voltage issue can be solved using an interposer, and many companies released 486 interposers or PCBs using PQFP Am5x86s with voltage regulators on a small PCB, like the Evergreen 586 133. There are modern reproduction interposers like the 486 socket blaster.
https://github.com/scrapcomputing/486SocketBlaster
The 50 MHz bus speed is more of a problem. The only CPU that will really work with the 50 MHz bus is the Am5x86, and you'll need a good binned chip. The Am5x86 has no problem doing 160 MHz on a 40 MHz bus with a 4x multiplier, but 50 MHz is pushing it. It will also take a 3x multiplier, so you could run it at 150 MHz. You will definitely need the 486 socket blaster or another interposer that exposes the multiplier to configurable jumpers. Most Am5x86 parts won't do 200 MHz, and those that do usually require more core voltage.
The Cyrix 5x86 likely won't work at all. Cyrix had a terrible time getting that chip even working, and they had to disable a whole bunch of advertised features in order to make it stable. Getting one much beyond 100 MHz is mostly a pipe dream, and you need a 33 MHz bus, not 50.
To change the bus speed on that, you might be able to remove the oscillator can and solder in a 14 pin oscillator socket so you could change the speeds. Full sized 5V TTL oscillators are getting harder to find these days, but you can still find some.
gen_angry@reddit
I think you’ll be pretty limited on this system. Not having VLB or PCI is a huge bottleneck at this stage, ISA alone just physically can’t carry enough bandwidth for duke 3d and especially quake. It’s a bus designed around the 8086.
Win95 is also a bit much for this system. Yes it “requires” a 386, but you’d still be on the pretty low end of the system chart especially being limited to ISA only. Remember in 1995, there were pentiums past 100mhz out by then, and they had PCI.
This would be fine for DOS 6.22 and doom though and pretty much every game from 1992 or so and earlier will scream on it.
If you intend to keep it and just use it for those older games, a sound blaster of some sort will do well. Avoid pnp versions if you can but may be difficult.
If you can snag a cheap 5x86 and want to try it out, it’d be a decent bump in CPU speed to a point. I wouldn’t expect miracles though.
The L2 module for this might as well be unobtanium. It doesn’t look standard.
kriebz@reddit
That L2 cache module is standard, to a point, but alas, it is indeed unobtanium. https://www.ardent-tool.com/misc/Turbocache.html
gatofisch@reddit
100% Been looking for one for my NCR MCA system for a while
GGigabiteM@reddit
With enough pictures and documentation, it may be possible to just build one, at least using the Intel cache controller IC.
The modules using PAL/GAL logic wouldn't be possible unless the PAL/GAL code was known to be able to burn them to new chips.
In either case, that's a whole lotta work.
gen_angry@reddit
Huh, TIL. Im familiar with COAST and cache DIPs but not those. That's neat.
Imobia@reddit
Ok that cpu isn’t in a zif socket. It looks to be on some sort of daughter board.
I don’t think you should try and remove that.
There is a cache slot, never seen that before. If you could locate that then sure try and add it.
Otherwise_End_8660@reddit
It's your regular LIF socket. You need the "comb" shaped thingy to remove it.
gnntech@reddit
This looks to be a pretty old 486 board with either 8mb or 16mb of SIMM ram. You can get a 486 dx/2 66mhz or a dx/4 100mhz chip in there.
It's possible you might be able to drop in a 5x86 chip to get up to 133mhz but the BIOS may have difficulty seeing it.
The bigger limitation is the bus on the board. It looks to be all 16-bit ISA slots. No VLB (which saw some popularity in the 486-era) and no PCI. This will limit what you can do in terms of video card upgrades.
Still a good 486 machine and worth it to get working properly. Would be a solid Windows 3.1 or OS/2 box.
techika@reddit
Socket 1 doesn't support dx2-dx4 Maximum is dx , and overdrvie at 5 volts
techika@reddit
I would rather bet on another motherboard, what you have socket 1 is the maximum you have put in. If you want to boost, put 256 cache, but you also need a cache controller. For a video card I recommend tseng labs et 4000 w32 isa, ram - the more you have, the better. For a hard disk it is good to see scsi with an isa controller.
I have everything you need for an upgrade, but the shipping cost will be more than you would find for another configuration.
wjn313@reddit
Nothing. It's perfect the way it is.
dametreus@reddit (OP)
Hello! I figured instead of responding to every comment individually id just make one big response lol. First off I wanna thank everyone for your insight and help! I really appreciate it! Sounds like the machine I got is still a good piece of kit just not for the era of games I was hoping for. That being said it still looks to be an amazing machine for Early 90s DOS and Win 3.1 games! I plan on putting a PicoGUS in there at the recommendation of a few of you guys and a floppy drive emulator. Probably gonna pick up an MT32Pi as well. The system itself already has a CD drive and 3 1/2 floppy so I should be set there! As for the games I initially wanted to play with this PC it sounds like at some point I need to build out a Pentium system for that! Again thank you all for your help! Ill be sure to come back here and post updates on this system when im able to get it finished up!
ThisBell6246@reddit
Look there is not much you can do with it, but it's not a bad machine, its just that a lot of the things we take for granted these days weren't a thing back then. That being said, you might be able to upgrade the RAM, install an ISA video capture card, Sound Blaster 16, ISA SCSI controller and network card, Multi I/O card etc. While the all the naysayers would say it cannot run this or that, I'd say give it a go. Sure it will never run Quake, but then who cares. There are thousands upon thousands of Dis and Windows 95 titles available that should run without issues. Think of Doom, Superfrog, Where in the world is Carmen Sandiego, StarWars Dark Forces. Jill of the Jungle, Another World, Commander Keen, 4D Stunt Driver, Wolfenstein etc.
cybermeuf@reddit
Also windows 95 can run with +4 MB of memory but more is better (upgrading simm memory can be tricky because they work in pair) - avoid the OSR 2.5 "desktop upgrade", you can pick up an early version because you will not be concerned about the evolutions in OSR 2/2.1 (agp, mmx, fat32, usb, directx…)
cybermeuf@reddit
- A sound card with OPL3/midi and a wavetable connector! I love my es1868 (isa but slightly more recent)
- a network card like a 3com 3c509
- a bigger hard drive or a second hard drive to experiment with windows, dos or os/2 :) (old bios struggle with +512 MB drives)
fondow@reddit
What is the cpu voltage? Late 486 don't have the same and you need an adaptor or an overdrive.
Marco-YES@reddit
Remove the barrel battery if it has one. Can't see under the cables.
dametreus@reddit (OP)
I already took the battery off, thankfully it was a separate box that connected to the board with a header