"Archmont" desktop 386DX-40 build

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"Archmont" desktop 386DX-40 build

Postby JidaiGeki » 2017-11-06 @ 13:16

I've got a few builds in the pipeline, but this one is tickling my fancy at the moment. To kick off, here's a pic of roughly where I'm at:

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I've never owned a full 386DX until now, as my 386 machines have otherwise ended up being SXs. Friends in the past had computers based on 32-bit 386s, but at home I skipped from an SX desktop straight to a Pentium, with only brief dalliances with cut-down 486s in laptops. So this is a bit novel, but it does fit nicely into my line-up.

This build didn't start out with a 386 focus. I bought the desktop case a couple of years ago as it was affordable, and I wanted to house a 486 motherboard with a DX4-100. Archmont was from memory just a vendor of re-badged clones here in Oz (not that that is a bad thing, of course). This is how it was when I first got it, it was mostly an empty shell with an Ahead ISA video card screwed in to the rear cage.

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Though it didn't come with a motherboard, the quality check date on the PSU and other bits suggested an original build of late 1991. The guy who sold it to me mentioned that it was a 386-based machine, before the barrel of death leaked and killed the motherboard, and corroded part of the case.

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I sort of fixed it up, sanding back some surface rust, and taping off and spraying the worst area inside and out. I couldn't match the bare metal finish of the case interior, and spraying the whole thing would be a waste of paint & time. Ultimately it's covered up by the motherboard so the repair area doesn't bother me.

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The origins of the motherboard are a mystery to me, I can't remember how or when I bought it, or who the seller was. Probably a spontaneous late night eBay purchase. Anyway, it has a ULSI 387 co-pro, and came with 8MB RAM installed. The problem was, half of it was parity, the other half non-parity. It wouldn't boot with all 8MB on-board, so the parity RAM has got the chop for the time being, and it got into full swing with 4MB. Maybe I'll consider 32MB next year, but it'll probably need all parity RAM then. The barrel battery is removed, and there isn't a replacement organised as yet.

The power supply arrangement is temporary; after some digging I found the proper power switch but to fit it means taking off the case front again, so for now the ultra safe arrangement is to have the switch dangling over the front. Cards that are going into it are a Tseng Labs ET4000 (with "Rainbow" BIOS); a Winbond floppy and IDE controller; an Adaptec SCSI/sound card (AMM1570); and possibly some other sound card to complement the Adaptec, maybe a GUS or SB depending on how the Adaptec sounds. The AMM1570's supposedly got on-board wavetable, but having read the two manuals for the card twice over I'm guessing that's only available in Windows as it's not mentioned much at all.

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The LED MHz display almost deserves a post to itself. Given that this was going to be a 486 build, I originally swapped out the 2-digit LED display, and put in a 3-digit display, which lined up perfectly with the aperture and screw holes and had standard jumper settings. Once I decided to go back to the 386, the 2-digit unit was more appropriate, so it was restored to its rightful place. Originally, I'd had a hard time figuring out how the 2-digit readout, an "AT-05C" model, worked. There are no instructions anywhere online. It has two banks of DIP switches, one row for tens, and the other for units.

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It wasn't immediately apparent to me how this worked, and only through logging various combinations did it become clear what was happening. The bank of 7 is for tens, the bank of 12 is for units. The switches for units seem to map roughly to the segments (theoretically it should have 14 switches, but it's working now, so no need to touch it again soon), while the switches for the tens (the bank of 7 switches) light up different combinations of segments that can be pieced together to make legible numbers. For the non-turbo mode, only the first three switches changed anything, giving readouts of 1, 2, 3 or blank. The non-turbo display range can only range between 1 to 39.

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Close enough wasn't good enough. The stray single black lead shown in a previous pic, when plugged into the motherboard's +ve turbo LED terminal, activated the Turbo mode. This then opened up the balance of the switches to give a greater range of displays. I haven't tested all combos but I'd imagine 99 is possible. I've set it at 40 now, and hooked up the Power and Turbo lights which are powerful enough to shine through the smoked plastic cover as shown.

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So where I'm up to is planning the next phase. The case seems to be a little out of square, so fitting drives and the blank drive cover is a physical challenge. The original power supply died on me but there are some on order. While I'd love an era correct monitor, I don't have one but my eyes are still peeled for that elusive 14" CRT. Finally, I've got a Seagate Hawk 1GB drive to go in, and the CD-ROM installed in the first pic is a 4x SCSI caddy loading Toshiba XM-3501B. Once those are hooked up, it'll be DOS 5 or 6.xx with Windows 3.11 on-board, and then it's DOOM time.

Thanks for looking, I'll try to update soon!
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Re: "Archmont" desktop 386DX-40 build

Postby jesolo » 2017-11-06 @ 15:34

Very nice build.

I think you might be a bit underwhelmed with Doom's performance on a 386DX.
A 486DX2-66 is recommended for a more "smooth" frame rate (above 25 fps).

It does, however, make for a great PC for playing the original Wing Commander :happy:
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Re: "Archmont" desktop 386DX-40 build

Postby bjwil1991 » 2017-11-07 @ 15:32

Wow. That's a nice system you got there. DIP switches for the turbo function? That's nice. The 486 I had from 1994-2012 had jumpers for changing the speed indicator (didn't have a manual for it).

My Packard Bell Pack-Mate 28 Plus's processor was upgraded from the dreaded i486SX2-50 to a DX2-66 since some of the games ran too slow or didn't work very well, and the turbo for it is just disabling and enabling the cache (CPU and on-board) for speed sensitive games (as well as Roland MT-32 games that work on 386 processors or older).
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Re: "Archmont" desktop 386DX-40 build

Postby BitWrangler » 2017-11-07 @ 16:56

I have never had problems mixing parity and non-parity SIMMs. Presuming there's a way to set the board for non-parity, it just ignores the extra bit. Only problems I can think of is if it doesn't let you set it by jumper or CMOS and tries using parity if it sees any parity SIMM.... or of course actual faulty modules, or speed issues.

I haven't played doom on a DX40, but on an SX40 it was okay with a half decent pixel pusher.... I would have thunk 32bit bus and cache would make a DX more betterer.

Edit: Yah the jumperable displays, I got fed up of changing speeds on them and ended up with mine saying "HI" and "LO", that was usually when I'd got 3 figure mhz in a 2 fig case though. These days, I'd be tempted to set them all to 88, because every time you turn them on you're going back in time.... however, 88 has unpleasant connotations also.
Basement full of ancient PC stuff, starting to go through it. Most recently toyed with DOS era stuff 15 years ago, so memory might be rusty. So what's this BitWrangler guy's deal ??? >>> http://www.vogons.org/viewtopic.php?f=25&t=56382
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Re: "Archmont" desktop 386DX-40 build

Postby Anonymous Coward » 2017-11-07 @ 23:02

In China, 88 means goodbye. What's so wrong with that?
Will the highways on the internets become more few?
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Re: "Archmont" desktop 386DX-40 build

Postby BitWrangler » 2017-11-07 @ 23:05

H is the 8th letter of the alphabet so the neo-nazis think they're being as clever as their enigma machines to use 88 to represent heil hitler.
Basement full of ancient PC stuff, starting to go through it. Most recently toyed with DOS era stuff 15 years ago, so memory might be rusty. So what's this BitWrangler guy's deal ??? >>> http://www.vogons.org/viewtopic.php?f=25&t=56382
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Re: "Archmont" desktop 386DX-40 build

Postby JidaiGeki » 2017-11-08 @ 01:16

Thanks for the replies and feedback!

@jesolo, yeah I think the 486 will definitely make Doom buttery smooth. It's been ages since I last played. I can remember when I first saw it being played though; in early 1994 my friend's family had a 386DX40, and I walked into their computer room to see his brother playing Doom in the dark with headphones on. Pretty cool stuff, big step up from Wolf3D. Later on that evening we cracked out the blank 3.5s and I had a copy :D My 386SX squeezed out a few frames of Doom, but his DX40 crapped all over my machine. If it becomes a grind I'll go take on the Kilrathi ...

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@bjwill, I do like the switches. Some engineer clearly realised that fiddling with numerous jumpers jammed into a T configuration in a small space was tricky and used the MHz limitations of the day for efficiency - guess he/she never thought there'd still be voltage going through it in 2017! I might put together an instruction sheet, but I sincerely doubt there are many of these in the wild.

@Anon, ah I didn't know that, so it must be in Cantonese that 8 means luck, fortune/wealth or similar? There are a lot of cars running around here with deliberate combos of 8 in their number plates, mostly since 1997...

@BitWrangler, I just put the other 4MB parity back in, it works! Must have been inserted poorly before, I tried it twice, including switching the banks around, but now there's a solid 8MB. And re 88, you learn something new every day :-S
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Re: "Archmont" desktop 386DX-40 build

Postby CkRtech » 2017-11-08 @ 08:12

Love where this build is going, JidaiGeki. Thanks for sharing.
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Re: "Archmont" desktop 386DX-40 build

Postby BitWrangler » 2017-11-09 @ 03:02

Heyyyy Wing Commander, gotta play that again, back in the day I think I got hung up on trying to win Kurasawa 2, I'd shoot down 3 of 4, then the last one would be a bastard and survive long enough to get a shot off that finished the ship I was meant to escort.
Basement full of ancient PC stuff, starting to go through it. Most recently toyed with DOS era stuff 15 years ago, so memory might be rusty. So what's this BitWrangler guy's deal ??? >>> http://www.vogons.org/viewtopic.php?f=25&t=56382
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Re: "Archmont" desktop 386DX-40 build

Postby JidaiGeki » 2017-11-09 @ 14:45

CkRtech wrote:Love where this build is going, JidaiGeki. Thanks for sharing.


Thanks so much CkRtech! I've made a bit of progress too, apologies for potato phone pics.

Last night I sat down with the SCSI drive and SCSI/audio card to set the jumpers. Didn't have enough tiny jumpers for the hard disk so I left parity off, but set appropriate IDs, termination, etc., and most other settings were at default. The Seagate Hawk drive is actually a 2GB unit, not 1GB, but the card can handle that. Decided against putting in a Barracuda, for a 386DX I'm sure 5400RPM is enough.

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Next on the to-do list was to sort out the power switch. Face off ...

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Then SCSI card and drive in, and HDD LED connected to the drive. Though 3.5" hard disks were around at the time this case was built, there is no 3.5" internal cage, so the Hawk sits in the 3.5"->5.25" adapter that I dug up. For ease of installation the 5.25" is at the bottom, as its length gets in the way of the cabling.

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Finally, both floppy drives in, CD-ROM attached, and covers installed. The CD-ROM is just a placeholder at the moment. I bought three of these Toshibas but none of them exhibit signs of life when power is connected, so further testing is required. From memory this was a picky drive, I actually bought one new in 1994 for $700! Ultimately though I think an IDE CD-ROM might be easier to deal with.

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The best part of this build has been that almost everything plays nicely! The SCSI BIOS picks up the drive, and it can boot from the card; the floppies both work. DOS 5 installation was a breeze, and after formatting the hard disk, and installing from 5 pristine floppies, it boots quickly into DOS Shell. Couldn't be happier with that. Installed the SCSI Audio driver from the Adaptec floppy, and then got ready for the next step ... DOOM.

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As jesolo rightly pointed out - the 386DX-40 doesn't cut the mustard in DOOM. I played through the first two parts of the first ep with the screen size at a legible dimension, but had to drop it back dramatically to get any decent framerate. It's on an ET4000, with a decent disk subsystem and 8MB RAM, so there isn't much more I can throw at this other than CPU power, so DOOM will have to wait for progress on a 486 build. Chose V1.2 over V1.666 but that surely doesn't make too much difference? Anyway I'm reaching up to that WC shelf tomorrow!

Again there was some upside, the sound works just fine. I can't compare the SB emulation to a real SB at the moment, but I found that this card does provide wavetable GM music in DOS, but it's fairly poor and tinny compared to the SB music. The percussion sounds OK though. Will need to turn down the volume using the software mixer as well. Will provide some feedback on WC once it's up and running.

BitWrangler wrote:Heyyyy Wing Commander, gotta play that again, back in the day I think I got hung up on trying to win Kurasawa 2, I'd shoot down 3 of 4, then the last one would be a bastard and survive long enough to get a shot off that finished the ship I was meant to escort.


I generally only managed to survive escort missions by burning ahead to the next waypoint, and waiting for the friendly ships to draw closer. This way I could knock off a couple of enemy ships and the mission was a tad bit easier.
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Re: "Archmont" desktop 386DX-40 build

Postby Cyrix200+ » 2017-11-09 @ 14:56

JidaiGeki wrote:<snip>... SCSI/audio card ... <snip> ... the SCSI Audio driver from the Adaptec ...<snip>


Huh, I did not know that this existed.
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Re: "Archmont" desktop 386DX-40 build

Postby Anonymous Coward » 2017-11-10 @ 01:56

It's definitely a weird card. I'm really curious why Adaptec didn't use chips from Creative or Mediavision though.
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Re: "Archmont" desktop 386DX-40 build

Postby JidaiGeki » 2017-11-10 @ 13:33

Anonymous Coward wrote:It's definitely a weird card. I'm really curious why Adaptec didn't use chips from Creative or Mediavision though.


The sound side of things is quite similar to the Cardinal MPC700A card, which I also have, and which I think pre-dates the Adaptec. It was what drew me to this card as I was looking for the Cardinal wavetable upgrade, which is an EPROM but seems to be vapourware. I'll have to find the Cardinal card for comparison.

I added a newer 15" CRT and Honeywell keyboard today, and played Wing Commander Academy for a little while. Much better playability than Doom from the WCII engine. Sound isn't so great though, effects are a let down. Will see what WC1 brings. Hope to possibly even complete the build this weekend!

Edit: now that I have sunlight again, here's a picture with the CRT and joystick. Makes WC:Academy a lot easier and fun! Need to add a mouse as well.

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Last edited by JidaiGeki on 2017-11-11 @ 04:39, edited 1 time in total.
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Re: "Archmont" desktop 386DX-40 build

Postby Robin4 » 2017-11-10 @ 17:51

Very nice build.. If i can do a suggestion; I would rather mount that 5.25 inch floppy drive in the second 5.25 bay or the top one.. Because 5.25inch floppy`s would easily get damaged when then are getting fold.. This would happen if your keyboard sits right in front of your desktop case. So there isnt much room to insert the 5.25 inch floppy and can accidentally bent your disk... The best setup would be.. 5.25 inch drive on the top, Cdrom in the middle.. Harddisk drive on the bottom.

I really do love the aesthetics of this build.. Specially those special system case power / turbo / hdd lighting included that smoke plexi door and dont forget that nice setting up turbo 7 segment display.. This really give me the Pre- 90s feelings..
~ At least it can do black and white~
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Re: "Archmont" desktop 386DX-40 build

Postby Robin4 » 2017-11-10 @ 18:00

Anonymous Coward wrote:It's definitely a weird card. I'm really curious why Adaptec didn't use chips from Creative or Mediavision though.


Maybe Creative chips where expensive back in the days because of licenses.. So most manufacturers go with cheaper solutions..

Same problem with those CMS chips.. Yes they where cheap aftermarket parts.. But like Creative kept this as a secret to the audience.. So because people didnt know which parts where used, you had to purchase expensive parts from creative.. (they had labled them with there own creative parts numbers)
Thats why most people didnt purchase these CMS chips because they where to expensive for what it would add to the soundcard.. And CMS was already over-ruled by the Adlib and soundblaster standards which where better.. So why would you buy to expensive optional add-on chips??
And that why the Adlib standard and Soundblaster standard came be more popular on the long run.. Most game developer had more intrest in the more supported Adlib and Soundblaster standards then CMS music..
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Re: "Archmont" desktop 386DX-40 build

Postby gdjacobs » 2017-11-11 @ 00:24

I love those door-and-tray CD-ROM drives!
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Re: "Archmont" desktop 386DX-40 build

Postby BitWrangler » 2017-11-11 @ 16:03

Yah, they do have that advantage that they don't grab anything when they retract, the big square tray fronts are all corners and snag stray cables or sleeves etc.
Basement full of ancient PC stuff, starting to go through it. Most recently toyed with DOS era stuff 15 years ago, so memory might be rusty. So what's this BitWrangler guy's deal ??? >>> http://www.vogons.org/viewtopic.php?f=25&t=56382
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Re: "Archmont" desktop 386DX-40 build

Postby chinny22 » 2017-11-17 @ 14:05

SCSI 386, Living the earlier 90's dream!
Also intrigued by the sound/scsi combo. Guess if you got say a MPU-401 and a MT32 it may hide the not so great sound a bit.
and sure Doom may suck on this, but Wold3d should be about right
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