VOGONS


First post, by davidrg

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Lately I've been building myself a 486DX4-100. This is probably the first 486 I've built in 15 years (I got distracted by unix workstations for a while, plus less free time when I finished university) and has been quite a lot of fun. Enough that I'm tempted to build more - perhaps recreate my families first computer that could play games (a 166Mhz Pentium) and maybe a 386.

Here is the machine in all of its yellowed glory (just booted to windows so the CRT, a Panasonic PanaSync E70i, would be less of a mirror):

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The specs so far are:

        CPU: AMD Am486DX4-100
Motherboard: DataExpert EXP4045
RAM: 32MB 60ns Fast Page
VGA: S3 805 VLB, 1MB RAM. Digital part# PC76H-EA originally out of a DECpc LPx (sadly I never owned the machine).
IO: 16bit ISA Winbond UN1072
Network: 3Com Etherlink III 3C509B-TPC
Audio: SoundBlaster ViBRA 16 CT2810 with a DreamBlaster X2GS
Gravis UltraSound Classic rev. 3.4
Drives: 200MB Western Digital Caviar
1GB industrial type CF Card
32X Mitsumi FX322M 32x CD-ROM (I would have preferred 4x but didn't have one handy and the 32x looks pretty much identical)
1.44M 3.5" Mitsumi/Newtronics D359T3
1.2M 5.25" Teac FD-55GFR

I set out specifically to build a fast(ish) 486 so part of my reason for grabbing this particular case from storage (aside from the built-in speakers) was my belief that it was a DX4-100. Seems at some point in the distant past I upgraded it to a 100MHz Pentium - probably in 2004 based on the dates on the hard disk. The soldered RTC chip in the Asus motherboard was dead so the motherboard & CPU have gone into an antistatic bag back into storage.

I imaged the hard disk that was already in the case before wiping it for this new build. I could have just done everything off of CF cards but I kind of miss the hard drive noises - it feels kind of weird loading games from the CF card in silence. Sadly the mounting bracket for both the hard disk and 3.5" floppy drive were gone when I first got the case 20+ years back so previously I held the floppy drive in place with duct tape and let the hard disk rest on the bottom of the case. At the moment I can't find my duct tape so I've just got to be careful when inserting 3.5" disks. The cable mess seems to provide enough resistance that the floppy drive doesn't push back into the case too easily.

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Getting it going was a bit of a challenge. Somehow I'd managed to avoid learning that there was a difference between FPM and EDO - back when I was in high school some 72pin ram just didn't work in some computers and it was a mystery as to why. Now I know why and my big box of RAM is now sorted.

Expansion cards were the other issue. Somewhere I have a box of VLB cards including some that are apparently quite fast for DOS (ARK1000PV and ExpertColor DSP6430/C&T F64300) and a bunch of I/O cards but I can't for the life of me find it. The only VLB cards I could track down were the S3 805 I'm using now and some NOS Pine cards that have an annoying option ROM. The S3 card seems nice enough though and the Winbond I/O card is at least stable. There is a little bit more detail on the S3 card in this thread.

Additionally, it seems like the 2nd 16bit ISA slot (second one up from the GUS just below the I/O card) doesn't work which caused a lot of confusion when I was trying to get this setup to POST reliably as at first I had a random VGA card in there. Sound cards installed in that slot simply don't work, and if I put the NIC there the NIC driver crashes on startup. No idea why but aside from a SCSI card I can't think what else I'd want to put in this machine anyway so its not really a problem.

As for the audio setup, the case has a pair of 5W 4 ohm magnetically shielded speakers in the front along with headphone and microphone jacks. IIRC they sound pretty good but I don't think I've heard them properly in 20 years because the volume control knob no longer works (the reason this case went into storage way back then). The toggle button next to the audio jacks is for switching between SoundBlaster and CD audio. I'm feeding CD audio into the sound card so for now its acting as a mute switch. I was tempted to see if I could rig it up as a SoundBlaster/GUS toggle but I don't think I'll bother now.

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I'm now feeding the GUS line out (more like speaker #2) into the ViBRA 16s line in and then feeding he ViBRA 16s line out to the case speakers and this seems to work pretty well. No switching between sound cards, I just have the SoundBlasters line-in set such that games using the GUS are about the same volume as games using the SoundBlaster. I would have set it up the other way round and fed the ViBRA 16 into the GUS line in for less noise but... the GUS mixer doesn't work at all and the card is always at max volume, where as the Creative mixer works just fine. I spent a while trying to make the GUS mixer work but perhaps it only works for certain applications or for the newer PnP cards. The 3rd 3.5mm audio cable in the back is just to hook up the front microphone jack. I very much doubt I'll ever use it but figured I may as well connect it up anyway.

Things still to be done:

  • Replace the (not yet leaking and still holding a charge!) soldered NiCd battery with a CR2032 (holders are slowly making their way from China)
  • Expand the GUS to 1MB
  • Replace the stereo volume control potentiometer
  • Add a DreamBlaster X2GS (on its way - I didn't pay for tracking so I guess it will just be a surprise in the mail eventually!)
  • Duct tape the floppy drive in place 🙁
  • Figure out how to feed the PC speaker into the SoundBlaster so I can use headphones (I've seen a couple of different wiring diagrams for this, all with missing details and some with warnings about hardware damage if you do it wrong)
  • Maybe patch the BIOS to fix its Y2K issue (it thinks its 2094). I'm running an NTP client on startup which sets the time correctly so its not really much of a problem at the moment.
  • Replace or lubricate the PSU fan (its noisy when cold)
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Last edited by davidrg on 2022-06-08, 08:49. Edited 3 times in total.

Reply 2 of 22, by Cuttoon

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amadeus777999 wrote on 2022-04-16, 08:52:

Did you try optimizing the settings?

He did. You can plainly see, it works. Optimal settings.

Nice machine - those speaker cases are bloody rare, there's a thread for them:
The AT cases with built-in stereo speakers thread!

You really should try to find a period correct 4x CD-ROM drive.
Then you'll get perks like noticing that it will not take certain CD-R types or none above 650 MB because, turns out, that was actually the initial standard... 😁

I like jumpers.

Reply 3 of 22, by davidrg

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I'm not really familiar with optimizing 486 systems so settings are pretty much all at their defaults at the moment. Anything in particular I should look into?

I've put some minimal effort into keeping a reasonable amount of free conventional memory (something I never really paid attention to in the past). Currently I'm running with 595K free which seems to be enough for everything I want to run for now. Freeing up more should be pretty easy if I hit something that needs more.

Annotated Memory Usage
Modules using memory below 1 MB:

Name Total = Conventional + Upper Memory
-------- ---------------- ---------------- ----------------
MSDOS 19,021 (19K) 19,021 (19K) 0 (0K)
HIMEM 1,168 (1K) 1,168 (1K) 0 (0K)
EMM386 3,120 (3K) 3,120 (3K) 0 (0K)
DPMS 1,808 (2K) 1,808 (2K) 0 (0K) Needed by PHOST (otherwise PHOST uses a lot more memory)
IFSHLP 3,872 (4K) 3,872 (4K) 0 (0K)
COMMAND 3,184 (3K) 3,184 (3K) 0 (0K)
CTMOUSE 3,104 (3K) 3,104 (3K) 0 (0K) Mouse driver
PHOST 10,256 (10K) 10,256 (10K) 0 (0K) Remote control thing. Can't load high, supports windows, IPX only.
SETVER 512 (1K) 0 (0K) 512 (1K) Not sure why I've got this actually
VIBRA16 21,536 (21K) 0 (0K) 21,536 (21K) Creative garbage
CTMMSYS 8,112 (8K) 0 (0K) 8,112 (8K) Creative garbage. I assume I could drop one or both of these if needed
MTMCDAI 11,264 (11K) 0 (0K) 11,264 (11K) Mitsumi CD-ROM driver
ANSI 4,240 (4K) 0 (0K) 4,240 (4K)
SMARTDRV 29,024 (28K) 0 (0K) 29,024 (28K)
DOSKEY 4,144 (4K) 0 (0K) 4,144 (4K)
MSCDEX 27,952 (27K) 0 (0K) 27,952 (27K)
SHARE 13,888 (14K) 0 (0K) 13,888 (14K) Needed by C++ or pascal compiler IIRC. Could go if needed.
Client32 3,504 (3K) 0 (0K) 3,504 (3K) Whole network stack (NIC driver, IPX, TCP/IP, DHCP client & network drives)
TINYH_N 34,144 (33K) 0 (0K) 34,144 (33K) Different remote control thing - supports TCP but not windows
Free 609,840 (596K) 609,520 (595K) 320 (0K)

Memory Summary:

Type of Memory Total = Used + Free
---------------- ---------- ---------- ----------
Conventional 655,360 45,840 609,520
Upper 158,640 158,320 320
Reserved 393,216 393,216 0
Extended (XMS) 32,347,216 8,916,048 23,431,168 Most of the XMS usage is the network stack - cache is currently set to 4MB.
---------------- ---------- ---------- ----------
Total memory 33,554,432 9,513,424 24,041,008

Total under 1 MB 814,000 204,160 609,840

Largest executable program size 608,880 (595K)
Largest free upper memory block 192 (0K)
MS-DOS is resident in the high memory area.

At this stage things seem pretty stable except sometimes on first boot games run extremely slowly - hitting the reset button fixes it every time. Not entirely sure what causes it - everything else seems fine. Probably a TSR misbehaving. Games under Windows aren't as stable as they could be either - I've had SimCity 2000 and other games lock up the machine a few times. Once I've crossed everything off the to-do list I'll try removing the remote control software and see if that fixes it. Could also be graphics drivers I suppose - I don't recall if I had those issues when I had a (faulty) OTI-087B card in the machine.

For me looking period correct is more important than actually being period correct - I'll happily stuff the machine with more RAM than anyone would have had back then but I won't put a 52x DVD burner in it. Luckily this 32x drive looks pretty much identical to the quad speed Mitsumi drives I've got somewhere so it at least looks the part but I suspect that drive is not entirely reliable so may get replaced anyway. I've got some MKE Panasonic drives somewhere (though only one plastered with creative logos) which would fit nicely. Though like the 5.25" floppy drive the CD-ROM drive is kind of just for show - it ought to be there even if I rarely need it. Only a single floppy disk was used to setup the machine and everything on it - all the software (including DOS) was installed from the network.

Reply 4 of 22, by Cuttoon

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Well, it's a VLB system, they never had the reputation of running very stable. Usually, there are some jumpers on the motherboard for "wait states", to harmonize VLB and FSB timings. The more, the merrier. But AFAIK, the Am486 DX4 was a "DX3" like the Intel, running at 3 x 33 MHz. And the wait states were mainly crucial for systems with 40 MHz FSB.
Of course, having two sound cards is already a luxury complication.

Sometimes, the BIOS setup has two different sets of default settings - "safe" and "optimized" so if it does not run stable on the latter, you could try that out.

Ah, the conventional memory battle... that's always great fun.
DOOM in 1993 came with the DOS/4GW extender that abolished the memory limit, but a game as late as 1994's Colonization still had the old problem, and was rather demanding...

I like jumpers.

Reply 5 of 22, by Gmlb256

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You could drop these Creative TSRs, they are unnecessary and are needed for Creative programs that you will never use (except the mixer software and CT-VOICE.DRV which some games requires it). There are SB16 drivers that doesn't require neither VIBRA16 nor CTMMSYS, another alternative is using UNISOUND for initialization.

Freeing you some UMB for more useful TSRs.

Reply 6 of 22, by davidrg

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Had a look at the motherboard jumpers manual on ultimateretro and nothing much there - just CPU & cache configuration (256K installed).

In the BIOS I've just got these settings but I don't really know what any of them do:

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Disabling auto-configuration just enables the three disabled options (SRAM burst read/write cycle, DRAM Wait State). I'm guessing there isn't really anything here that would make a particularly significant performance impact and I'd be better off figuring out where I put those faster VLB video cards. At the moment Doom and Terminal Velocity run well, Duke3D is playable (at 320x200), Quake runs too slowly to really be playable (I assume this really wants a pentium).

As for conventional memory, is there a list anywhere of games requiring particularly large amounts? So far my (relatively limited) selection all run fine in 595K but I could get to 611K free without sacrificing anything I use frequently if the need came up.

Reply 7 of 22, by Gmlb256

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Quake needs a Pentium CPU because it uses the FPU which on the 486 is slow and not pipelined.

For conventional memory 611K is fine for most DOS games. AFAIK there isn't a proper list of DOS games that demands a lot of conventional memory but one that I heard is Dark Sun: Wake of the Ravager.

Reply 8 of 22, by CoffeeOne

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davidrg wrote on 2022-04-19, 01:20:
Had a look at the motherboard jumpers manual on ultimateretro and nothing much there - just CPU & cache configuration (256K inst […]
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Had a look at the motherboard jumpers manual on ultimateretro and nothing much there - just CPU & cache configuration (256K installed).

In the BIOS I've just got these settings but I don't really know what any of them do:
PXL_20220418_101532525.jpg
Disabling auto-configuration just enables the three disabled options (SRAM burst read/write cycle, DRAM Wait State). I'm guessing there isn't really anything here that would make a particularly significant performance impact and I'd be better off figuring out where I put those faster VLB video cards. At the moment Doom and Terminal Velocity run well, Duke3D is playable (at 320x200), Quake runs too slowly to really be playable (I assume this really wants a pentium).

As for conventional memory, is there a list anywhere of games requiring particularly large amounts? So far my (relatively limited) selection all run fine in 595K but I could get to 611K free without sacrificing anything I use frequently if the need came up.

Hi,

I agree that better timing would'nt bring sooo much.
But still, with external 33MHz you should ALWAYS be able to use 2-1-1-1 for cache. 3-2-2-2 is a setting for external 50MHz, if your board cannot handle 2-1-1-1 it would be really weird.

Reply 9 of 22, by chinny22

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Nice rig,
re-learning of finding out about things about 20+ year old hardware for the very first time is a big part of the fun.
Back in dark ages memmaker was my only trick to free up memory for example, these days everything's 2 seconds away on the internet.
486's are great, I've got 3 but they aren't the best dos retro box, too fast for old games too slow for late dos SVGA titles, a Pentium is really a better suited rig for late dos

There you go a reason to build that other rig PLUS you could fire up a network game of doom 😉

Reply 10 of 22, by davidrg

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Yeah, its been a lot of fun re-learning this stuff again. I had to actually google which way round the motherboard power connectors went - when I was a kid I didn't even have to think about it! Though I'm sure I never knew about DOS memory management back then - I was just lucky the NetWare client didn't use conventional memory and whatever other TSRs I used didn't use enough to cause problems. I don't think it was until mid last year when I saw the DOS 6 conventional memory tricks thread that I actually learned any of this so of course I immediately fired up my DOS computer at the time and set about trying to free as much memory as possible.

I think I'll absolutely build a Pentium next - once this 486 is finished and its off the dining room table. The volume control potentiometers finally arrived (hope they're the right size) - now just waiting on GUS RAM and the battery holder. I'll probably want to figure out how to route the PC speaker into the sound card too - the cases built in speaker is very quiet at the back under the PSU.

I'm pretty tempted to build a 386 and something older too - pretty sure I have some nice AT (or maybe XT) clones that ought to be restored. Not sure what I'd actually use them for that the 486 couldn't handle though; I don't think I actually have any speed-sensitive games. But if nothing else selecting some hardware, building the things and getting them on to the LAN and running nicely should be fun.

Reply 11 of 22, by kolderman

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The glory days where the old guard 486 was making it's last stand against the Pentium upstart, and beating it. I remember that point of time well. It also kind of represented the last stand of DOS too.

Reply 12 of 22, by Gmlb256

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kolderman wrote on 2022-04-28, 20:56:

The glory days where the old guard 486 was making it's last stand against the Pentium upstart, and beating it.

Off-topic: Beating it? Not sure about that when taking account that Pentium was dual-pipelined and the 486 getting relegated into the low-end by that point. It is not just the FPU performance.

Reply 13 of 22, by kolderman

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Gmlb256 wrote on 2022-04-28, 22:48:
kolderman wrote on 2022-04-28, 20:56:

The glory days where the old guard 486 was making it's last stand against the Pentium upstart, and beating it.

Off-topic: Beating it? Not sure about that when taking account that Pentium was dual-pipelined and the 486 getting relegated into the low-end by that point. It is not just the FPU performance.

The 486 DX4 100 outperformed early Pentiums for typical software that was not necessarily optimized for the Pentium. It didn't last long, but it was a nice moment in time.

Reply 14 of 22, by Gmlb256

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kolderman wrote on 2022-04-28, 23:03:
Gmlb256 wrote on 2022-04-28, 22:48:
kolderman wrote on 2022-04-28, 20:56:

The glory days where the old guard 486 was making it's last stand against the Pentium upstart, and beating it.

Off-topic: Beating it? Not sure about that when taking account that Pentium was dual-pipelined and the 486 getting relegated into the low-end by that point. It is not just the FPU performance.

The 486 DX4 100 outperformed early Pentiums for typical software that was not necessarily optimized for the Pentium. It didn't last long, but it was a nice moment in time.

Touché. Many consumer software wasn't optimized for Pentium CPUs prior becoming mainstream.

Reply 15 of 22, by davidrg

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That is something I've kind of wondered about. Why does the DX4 even exist and what was its market position? The Pentium had already been on the market for a year when the first DX4 came out and writeback version came out at the same time as the 75-120MHz P54C Pentiums. Who was buying DX4s instead of Pentiums and what was the price difference? Was the DX4 just a super budget/value offering for the cheapest of the cheap PCs? Or were the early Pentiums sold exclusively as business machines?

Back in the early-mid 2000s I was just taking any PC that was offered to me for free and ended up accumulating quite a mountain of them. I ended up with plenty of 386, 486DX and DX2 but very few DX4. Perhaps 3-4 in total with only one of them being PCI based. I think I only ever had one P5 Pentium (a 60Mhz Deskpro XL which I still have) but I had (and mostly disposed of) a few dozen P54C Pentiums (mostly Venturis 575, Prolinea 575e and Deskpro 2000 100-120Mhz plus various generic/custom PCs). I don't know how representative my hoarding was of the NZ PC market 5-10 years prior but it seems like both the DX4 and first generation Pentium were quite uncommon - I guess everyone just went from the DX2-66 straight to the P54C Pentium.

Reply 16 of 22, by chrismeyer6

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486s lasted a good while into the 90s as the price premium for a Pentium based computer was significant. The 386 was still quite common during the 486 and early Pentium days. Back then computers were very expensive and people tended to hold on to them a lot longer than they do now.

Reply 17 of 22, by kolderman

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davidrg wrote on 2022-04-28, 23:31:

That is something I've kind of wondered about. Why does the DX4 even exist and what was its market position? The Pentium had already been on the market for a year when the first DX4 came out and writeback version came out at the same time as the 75-120MHz P54C Pentiums. Who was buying DX4s instead of Pentiums and what was the price difference? Was the DX4 just a super budget/value offering for the cheapest of the cheap PCs? Or were the early Pentiums sold exclusively as business machines?

Back in the early-mid 2000s I was just taking any PC that was offered to me for free and ended up accumulating quite a mountain of them. I ended up with plenty of 386, 486DX and DX2 but very few DX4. Perhaps 3-4 in total with only one of them being PCI based. I think I only ever had one P5 Pentium (a 60Mhz Deskpro XL which I still have) but I had (and mostly disposed of) a few dozen P54C Pentiums (mostly Venturis 575, Prolinea 575e and Deskpro 2000 100-120Mhz plus various generic/custom PCs). I don't know how representative my hoarding was of the NZ PC market 5-10 years prior but it seems like both the DX4 and first generation Pentium were quite uncommon - I guess everyone just went from the DX2-66 straight to the P54C Pentium.

The DX4 was an upgrade option I believe, and a very popular one at that. A brand new Pentium system would have cost upwards of 3k in late 90s $$$ around this time. And given it could match early Pentiums in performance, it was a no-brainer for those say running a DX2-66. I think I recall being amazed at how well Tie Fighter ran on the DX4, a game that seriously pushed systems at the time. I was obviously the last gasp for the 486 platform, but just today lost of people will choose to upgrade if they can.

Reply 18 of 22, by chinny22

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Our first PC was in early 1995, a DX2/66 that was cheap at $1000 Aussie dollars and that didn't include the screen
(Basically a pallet went missing, the company claimed it on insurance, pallet sowed up so they sold off quick at a discount)
My mate got a Dx4/100 towards the middle of '95 which replaced a 386/40
First Pentium I came across wasn't till 96 or 97? and that was a friend whos family wasn't rich as such but did have more disposable income then the typical family.

This was all before the internet became really common place and stand alone PC's don't need updating nearly as much.
I'd say people that did need to upgrade from their 386 for whatever reason probably did it when the Dx2/66 offered the best bang for buck.
As Win95 and/or dialup became more mainstream that was probably the next major cause for people to upgrade, but that wouldn't be till around 96 or so for the average person by which time Pentiums had dropped enough in price to become affordable to the average income family

Reply 19 of 22, by Anonymous Coward

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The main obstacle to buying a Pentium was the cost of memory. At least my situation was that there wasn't much point to upgrading to a Pentium if you couldn't afford more than 8MB of RAM. By the time I could afford the RAM the P5 architecture was basically finished.

DX4 wasn't that popular in my area either. I knew a lot of people with PCs, but I only ever met one guy with a DX4 in his desktop PC. I think he got it really late too...around 1997. I did encounter the DX4-75 somewhat often in laptops though. In the late 90s, I encountered loose DX4 CPUs sometimes, but they were always the AMD version. I think the first time I ever saw an Intel DX4 in the flesh was around 2001, when I went out of my way to buy it on eBay because I was really curious.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium