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386 SX40 build

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First post, by Andy1979

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Hello all, my first post on this forum.

I recently rescued a pile of old computer parts from my parents' loft. My first PC was actually a generic Pentium 120 AT system assembled by a local company in 1996. Since then I've always built my own systems, gathering a small collection of surplus parts along the way.

Amongst the bits and pieces in the loft was a 386 AT tower system, which I first cobbled together 15 years ago out of the tower from my P120 when the PSU and motherboard died, an AMD 386SX40 motherboard, 4x1mb SIMMS and an ISA graphics card that I'd found in a 'junk box' at a computer fair about 20yrs ago. I already had a basic ISA multi I/O card that had seen previous use in my pentium.

In addition at some point I was given an old 5 1/4 inch floppy and a Tandon TM262 21mb MFM hard drive and Western Digital controller card which I thought I'd try and get working in this.

I can't find much info on the board, which seems to be a generic 'made in China' model from circa 1992. I did find something almost identical on eBay which was labelled as an 'ML765 V3', and has 'Firenze Research Lab' as the manufacturer. Mine has no such markings. The graphics card looks to be an Acumos AVGA1.

Unfortunately the board has suffered battery leakage while in storage, which had damaged one of the tracks to the keyboard socket. I was able to clean things up with the usual vinegar/water/IPA process, and repair the track damage with a wire. The keyboard BIOS socket had also been damaged on one pin, which I was able to fix with a small piece of metal.

Currently the system will boot from floppy and I can access the AMI bios, but any attempt to boot from hard disk (using either the IDE port or the WD MFM controller) meets with an 'HDD Controller failure' error message. Think I need to try all the various permutations of expansion slots as there are no address jumpers on my IDE controller card.

The other weird thing is that the RAM shows up as 3840K when all 4mb is installed. Also cannot seem to get the machine to recognise any more than 4mb, although the only other 30pin SIMMS I own are 2x256k so it's not like that's a big deal.

Am hoping that the above issues aren't due to battery damage to any internal layers of the board.

Keen to get this up and running for some period correct gaming / software. I have DOS 6 and Windows 3.11 on floppy, and some software from my father's old 386 laptop (which we sadly no longer have). I'm also building a Pentium 133 system, so don't need it to run anything too demanding. I have an 81mb IDE drive to use with it for now, but ultimate plan is to use a 128mb compact flash.

Have attached a few photos in case anyone is interested, or can identify the board.

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Last edited by Stiletto on 2020-08-11, 21:55. Edited 2 times in total.
Reason: Restoring revision 17027

My Retro systems:
1. Pentium 200, 64mb EDO RAM, Matrox Millennium 2mb, 3DFX Voodoo 4mb, DOS6.22 / Win95 / Win98SE
2. Compaq Armada M700 laptop, PIII-450, Win98SE
3. Core2Duo E6600, ATI Radeon 4850, Win XP

Reply 1 of 25, by jesolo

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Welcome to the forum.

Starting with the motherboard, it was manufactured by Micro Leader Enterprises.
Check here if you can perhaps find your motherboard: http://arvutimuuseum.ee/th99/#1 (look under 386 motherboards for a schematic that is similar to yours).
This will help you with memory installation and what the motherboard supports.

MFM drives are a bit more tricky to set up and, in most cases that you change controllers, you need to low level format the drive (this can be done via the DOS Debug command).
Take some pictures of the drive and the controller.
Do you have both the 34 pin and 20 pin cables?
Just be careful with those old MFM drives (handle with care). The older models had to have their heads parked manually.
Depending on the model, you normally selected a pre-defined hard drive number in the CMOS setup and then you would have to boot up in DOS and low level format the drive.

However, for a 386 PC, I would recommend you rather go with an IDE drive (together with an IDE controller card).
The hard drives are becoming scarce, but you can still find IDE controller online. For the former, a Compact Flash (CF) card is a good alternative.

Reply 2 of 25, by Andy1979

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Thanks Jesolo

That link is a great resource, but unfortunately I can't seem to find a similar schematic with the two bios chips between the ISA slots and the 8 SIMM slots.

Definitely planning to go IDE, really just wanted to try the MFM drive out of curiosity to see if it still works (it powers up, so that's a start). Hasn't been powered up for at least 16yrs.

Last edited by Stiletto on 2020-08-11, 21:56. Edited 2 times in total.
Reason: Restoring revision 17028

My Retro systems:
1. Pentium 200, 64mb EDO RAM, Matrox Millennium 2mb, 3DFX Voodoo 4mb, DOS6.22 / Win95 / Win98SE
2. Compaq Armada M700 laptop, PIII-450, Win98SE
3. Core2Duo E6600, ATI Radeon 4850, Win XP

Reply 6 of 25, by Andy1979

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MMaximus wrote:
AllPlatformsGamer wrote:

Nice build, also with CRT monitor!

Nice build. Looks like a TFT monitor to me though 😉

Thanks - will be nice if it works. It is a TFT, but bezels are so large it looks retro now.

All the CRTs got thrown away years ago as there wasn't space 🙁 My only remaining CRT is CGA/TV resolution and belongs to my Acorn A3010.

Sadly between the Pentium and the 386 I only have one ISA soundcard, which is an Opti 82C925 I think. Will have to keep an eye out for something suitable.

My Retro systems:
1. Pentium 200, 64mb EDO RAM, Matrox Millennium 2mb, 3DFX Voodoo 4mb, DOS6.22 / Win95 / Win98SE
2. Compaq Armada M700 laptop, PIII-450, Win98SE
3. Core2Duo E6600, ATI Radeon 4850, Win XP

Reply 7 of 25, by Andy1979

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Success! I was an idiot and was missing a jumper on the I/O card.

IMG_3748.JPG

Now have DOS 6.22 and Windows 3.11 installed. Amazingly Scandisk surface scan reports no errors on the 81mb Connor IDE drive.

Next problem - various clear-outs have left me with only PS/2 (or USB) mice. I currently have a Microsoft Intellimouse 1.3A wheel mouse connected to a PS/2 to serial adapter, but none of the built-in Windows 3.11 mouse drivers will work with it. Need to try and find a driver that works.

At the weekend I will investigate using the CF card adapter, see if I can get the 5.25inch drive working and hopefully solder in a replacement CMOS battery (am thinking to use a 3.6V cordless phone pack, so it can be mounted away from the motherboard).

Last edited by Stiletto on 2020-08-11, 21:57. Edited 4 times in total.
Reason: Restoring revision 17029

My Retro systems:
1. Pentium 200, 64mb EDO RAM, Matrox Millennium 2mb, 3DFX Voodoo 4mb, DOS6.22 / Win95 / Win98SE
2. Compaq Armada M700 laptop, PIII-450, Win98SE
3. Core2Duo E6600, ATI Radeon 4850, Win XP

Reply 9 of 25, by chinny22

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Try the Ps2 to serial adapter in a newer computer, good chance the mouse isn't serial compatible and passive adaptors don't work like PS2 to USB adaptors.

I liked the 2 black 5 1/4 drives in the beige case, suited it well.
Sound cards are one of the most enjoyable parts to get, maybe moreso for the Pentium, just having the one card is a good problem to have!

Reply 10 of 25, by Andy1979

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@MMaximus - Yes, I am in the UK.

Managed to find a BNIB serial mouse for £6.49 on eBay so have ordered one of those. Always a useful thing to have if you like messing with old computers.

@chinny22 - the black Tandon TM262 will be going back in if I can get it working. If it turns out the drive is toast I might keep the bay adapter anyway as I agree it suits the case. Don't think I need a CD Rom in this system.

Have ordered a (used) SB16 Value PNP from Amazon (CT2890) which was the same card I had 'back in the day'. Will put that in the Pentium and try the Opti card in the 386. I see there's a whole sub-forum for soundcards on here - know that card isn't one of the best, but I'm just looking for something that works without spending the earth and feels authentic to me as it's very similar to what I used at the time.

Last edited by Stiletto on 2020-08-11, 21:57. Edited 2 times in total.
Reason: Restoring revision 17031

My Retro systems:
1. Pentium 200, 64mb EDO RAM, Matrox Millennium 2mb, 3DFX Voodoo 4mb, DOS6.22 / Win95 / Win98SE
2. Compaq Armada M700 laptop, PIII-450, Win98SE
3. Core2Duo E6600, ATI Radeon 4850, Win XP

Reply 11 of 25, by Andy1979

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BNIB Mouse Systems serial mouse received yesterday, complete with driver disk. Wonder where it's been for the last 20yrs? Good weight to it and very smooth, I'm pleasantly surprised. Might use it with my P133 system too.

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Am now maxing out the 256k AVGA1 card at 800x600x16 in Windows. Although I found a driver for it, the default Windows 3.1 SVGA driver seems to work best - colours were washed out with the Acumos driver. Cirrus Logic GD5401 drivers didn't work (believe AVGA1 was rebranded to this after CL purchased Acumos).

Hopefully the new CMOS battery will arrive today/tomorrow so I can get things set up properly.

Last edited by Stiletto on 2020-08-11, 21:57. Edited 2 times in total.
Reason: Restoring revision 17032

My Retro systems:
1. Pentium 200, 64mb EDO RAM, Matrox Millennium 2mb, 3DFX Voodoo 4mb, DOS6.22 / Win95 / Win98SE
2. Compaq Armada M700 laptop, PIII-450, Win98SE
3. Core2Duo E6600, ATI Radeon 4850, Win XP

Reply 12 of 25, by Andy1979

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Some further success. Found the jumper settings for the MFM controller, and after a lot of trial and 'ROM BASIC' errors it finally booted into DOS 5.0 with a working copy of QBasic (yay - Gorillas!) and Word Perfect 5.1. It's very slow, but I love the physicality of the drive as you can see the servo turning back and forth. Looks like the machine it came from was last used in 1994. Currently running a surface scan.

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I also got the 5.25inch floppy going. Turns out the Epson 621-L is only a 360K drive, but that's OK as I only have DSDD floppies anyway. Routing the floppy cable to use both drives was proving difficult, but found a jumper on my I/O card that reverses drives A & B - problem solved.

Next job is to fit the new CMOS battery and get the CF card set up. Think I will leave the MFM drive in the case disconnected, as it won't work in tandem with my IDE controller. Must remember to park the heads first though!

Last edited by Stiletto on 2020-08-11, 21:58. Edited 2 times in total.
Reason: Restoring revision 17033

My Retro systems:
1. Pentium 200, 64mb EDO RAM, Matrox Millennium 2mb, 3DFX Voodoo 4mb, DOS6.22 / Win95 / Win98SE
2. Compaq Armada M700 laptop, PIII-450, Win98SE
3. Core2Duo E6600, ATI Radeon 4850, Win XP

Reply 13 of 25, by Andy1979

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Almost finished now. Soldered pins in place of the CMOS battery and mounted a 3.6V NiMH pack from a cordless phone safely away from the motherboard using sticky velcro. Seems to be keeping time and remembering the BIOS settings after leaving it on for a day to charge up, which is good as the battery was only reading 0.3V when it arrived.

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CF card is also mounted and working. Left the older MFM and IDE drives in situ in case I ever want to use them. Also installed a 3Com network card.

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Should have a more suitable keyboard somewhere, though when I get my other retro machines up and running am planning to use my old Microsoft Natural Keyboard Elite. Now it's time to play some games! Last job will be to install a sound card when I find something appropriate.

My Retro systems:
1. Pentium 200, 64mb EDO RAM, Matrox Millennium 2mb, 3DFX Voodoo 4mb, DOS6.22 / Win95 / Win98SE
2. Compaq Armada M700 laptop, PIII-450, Win98SE
3. Core2Duo E6600, ATI Radeon 4850, Win XP

Reply 15 of 25, by probnot

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Andy1979 wrote:
Almost finished now. Soldered pins in place of the CMOS battery and mounted a 3.6V NiMH pack from a cordless phone safely away […]
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Almost finished now. Soldered pins in place of the CMOS battery and mounted a 3.6V NiMH pack from a cordless phone safely away from the motherboard using sticky velcro. Seems to be keeping time and remembering the BIOS settings after leaving it on for a day to charge up, which is good as the battery was only reading 0.3V when it arrived.

IMG_3774.JPG
IMG_3777.JPG

CF card is also mounted and working. Left the older MFM and IDE drives in situ in case I ever want to use them. Also installed a 3Com network card.

IMG_3781.JPG
IMG_3789.JPG

Should have a more suitable keyboard somewhere, though when I get my other retro machines up and running am planning to use my old Microsoft Natural Keyboard Elite. Now it's time to play some games! Last job will be to install a sound card when I find something appropriate.

Nice rig! What are those yellow ground(?) wires going to the floppy screws and I/O cover screw for?

Also, I have a similar situation with RAM on my 386. Yours only reports 3840k (from 4096k), so 256k is missing. Mine (with 6mb) reports 5760k (from 6144k) so 384k is missing. I wonder if these older motherboards reserved it for something?

Reply 17 of 25, by Andy1979

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probnot wrote:

Nice rig! What are those yellow ground(?) wires going to the floppy screws and I/O cover screw for?

Also, I have a similar situation with RAM on my 386. Yours only reports 3840k (from 4096k), so 256k is missing. Mine (with 6mb) reports 5760k (from 6144k) so 384k is missing. I wonder if these older motherboards reserved it for something?

Thanks.

The yellow wires were installed by the system builder who supplied my Pentium system in 1996 (where the case came from), so I left them in. Assume they are for grounding as you suggest. They were quite thorough - all of the drive connectors had also been fixed in place with a glue gun, in a way that they could still be removed for upgrades.

Interesting that you also have 'missing' RAM, and that the amount seems to scale linearly. (With 2mb mine reports 1920k). I had initially assumed it was shadowing the video RAM which is 256k, but perhaps not? My first real PC was a Pentium with 16mb and I don't remember it doing this, but I seem to recall my Dad's 386 laptop with 2mb also reported 1920k on start up.

My Retro systems:
1. Pentium 200, 64mb EDO RAM, Matrox Millennium 2mb, 3DFX Voodoo 4mb, DOS6.22 / Win95 / Win98SE
2. Compaq Armada M700 laptop, PIII-450, Win98SE
3. Core2Duo E6600, ATI Radeon 4850, Win XP

Reply 18 of 25, by i486_inside

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probnot wrote:

Also, I have a similar situation with RAM on my 386. Yours only reports 3840k (from 4096k), so 256k is missing. Mine (with 6mb) reports 5760k (from 6144k) so 384k is missing. I wonder if these older motherboards reserved it for something?

As a result of the original IBM PC only having a 20bit Address space, there was only enough address space for 1MB so many peripherals use memory addresses in the upper memory area, a lot of times the computer bios and graphics card bios may be shadowed in the UMA, option roms on various ISA cards may use addresses from the UMA, portions video ram may be mapped to addresses in the UMA.

Reply 19 of 25, by Andy1979

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System now has an Opti 82C925 sound card installed. Not exactly period correct, but it emulates an SB Pro and it works, albeit a little noisily. Most of my games are from 1994-1997 for which I'm building a separate P133 system with an SB16 anyway.

Had thought the card was Adlib compatible, but Rick Dangerous 2 seems to crash when I select Adlib audio. Perhaps an IRQ problem?

My Retro systems:
1. Pentium 200, 64mb EDO RAM, Matrox Millennium 2mb, 3DFX Voodoo 4mb, DOS6.22 / Win95 / Win98SE
2. Compaq Armada M700 laptop, PIII-450, Win98SE
3. Core2Duo E6600, ATI Radeon 4850, Win XP