386DX40 build

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386DX40 build

Postby DonutKing » 2010-12-29 @ 06:19

After building my 486DX2, I had a heap of parts that I wasn't using and it seemed a shame for them to just sit there.
Fortunately I came across a brand new 'Contaq' brand 386 motherboard on ebay, going for about $25. The seller seems to have a bit of stock of these so if you are looking for a 386 board this is the go :)

Anyway, had a bit of free time over the Christmas break so decided to whack together another old machine. We're aiming for a 92-93ish system.

First, the motherboard.
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Comes with a manual and that's it.
It has an SiS chipset (the big chip in the centre) while the other two large chips are marked 'Contaq'.
On the left are the cache sockets, the board comes with 128kb of cache and has one bank empty.
The large socket in the lower centre is for the 80386 CPU while the smaller socket is for the maths co-processor, or 80387. Note the lack of a lever, this is before zero-insertion force sockets came around, so installing and removing processors can require a bit of carefully applied force.

The battery is one of the old barrel types; thankfully it hasn't leaked. I wanted to test the board to confirm that its flat so I'll start the system outside the case, before I remove the battery.

Now for the goodies... The legendary Am386DX-40; Intels own 386 only went up to 33MHz, while AMD's 40MHz 386 could compete with early 486's for a much more attractive price. You can read more about the 386DX-40 at the Red hill Guide.

I have also installed an 80387 Maths Coprocessor; although this is a 33MHz unit it seems to work fine with the 40MHz CPU. I ran a couple of utilities, 87TEST and COPCHK22 which confirm it works properly. There's precious little software I can put on this system to make use of the 387 apart from AutoCAD and Falcon 3.0 but its nice to have :)
The extra pins on the copro socket are for a Weitek 3167 coprocessor; they were faster than the 80387 but not software-compatible, software had to be written specifically for the 3167 to use it.

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Now for the memory. Here we have 8x 1MB 30 pin SIMM modules. These SIMMs are 8-bits wide (9 with parity) so you need to install them in multiples of 4 to match the 386DX's 32-bit bus. (The 386SX had a 16-bit bus and so only needed SIMMs installed in multiples of 2. The smaller bus width was to reduce motherboard complexity and therefore cut costs, however performance suffered as a result).

These modules are Toshiba branded; not sure where they came from but I had 8 identical modules so that's why I went for them. 8MB is actually quite a lot for this era but I have stacks of this stuff so I might as well use it.

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Now to plug in a video card. I went for the Tseng Labs ET4000AX; this was a well known card in its day for its excellent speed. This was mainly due to its high ISA bus throughput compared to other cards of the time.

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Anyway, connected the power and fired up the board, everything works well. However, I confirmed that the battery was indeed flat as it wasn't keeping BIOS settings after shutdown. So the old barrel battery was removed and an external battery fitted:

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Now, on to the case. A couple of months ago I bought two desktop cases from OCAU. Rather than reposting photos here is a link to the original post containing the photos:
http://forums.overclockers.com.au/showp ... ostcount=7

Interestingly, the system inside it was a Socket 4 Pentium, not Socket 7. Socket 4 was the original socket for 5V, 60 and 66MHz Pentiums and is quite exotic because most people were still buying 486's/586's until the Socket 5 and 7 Pentiums came around and the Pentium's price dropped. Socket 5 CPU's will work in a Socket 7 board however Socket 4 has a regular, square pin grid array, while 5/7 have a staggered pin grid array. so Socket 4 CPU's won't fit in the later boards. This is interesting for my collection, and it may even have the f00f bug - will need to investigate one day...

Anyway, Socket 4 was only around for a year or so until socket 5 came along, so this puts the case at roughly 93/94 so just about perfect for my needs.

The case needed a bit of a cleanup but it came up pretty good.

Once the board was mounted in the case I had a bright spark and pulled out an old, dead 486 motherboard I had. It had almost the same type of cache chips as the ones on this board. I ripped it out and installed the cache chips in the 386. There was a single jumper I needed to change to set the board up to use 256KB of cache instead of 128KB. I also had to change the TAG RAM chip - top left chip with small writing - with one of the new chips.

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This is, again, a lot of cache for the era and would have been quite expensive if it were bought new.

After plugging in the chips, I booted up and ... Success!

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So now everything is coming together. At this point I plug in the front panel headers. I discovered that the LED display on the front panel was set to read '60' so I needed to change that. This is set by jumpers on the back of the panel, I had to take the front of the case off to get at them. They can be set to any arbitrary characters you like. After a bit of trial and error, I set the panel to say '40' in turbo mode and 'LO' when turbo is disabled.

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Now for the expansion cards. Here is the IDE-I/O controller card I used:

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It had the jumper settings printed on the board which is always handy. This card contains the serial, parallel, floppy and IDE ports for the system. Nowadays all these things are integrated into the motherboard.

I have installed a 3.5" and a 5.25" floppy drive, so I will have both A and B drives. The 5.25" drive uses a board edge connector instead of the rectangular pins like 3.5" drives do. Rather than jumper settings like hard drives, the A and B drives are determined by the twist in the cable. The drive attached after the twist is the A drive.

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The hard drive I used is a Connor 425MB. This BIOS doesn't automatically detect the drive so the drive settings - cylinders, heads, and sectors - had to be entered manually. modern BIOSes will do this for you, which is a good thing because if you enter these incorrectly you can cause the drive to 'wrap around' to the beginning of the disk and start overwriting data. Often this problem wouldn't become evident until after enough data had been written to the drive.

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Now, the sound card. This is a Sound Blaster Pro, model CT1690. sound Blaster 16's are a lot more common however they are not 100% SB PRO compatible; there are certain games that work better with the Pro than a 16.

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It has a Sony CDROM interface built into it; this is because early CD ROM drives were not IDE compatible so you needed controller cards to use them. These controllers were often integrated into sound cards as part of a 'multimedia package'.

The CDROM I am using is a Sony CDU-33A-01. Its a double speed drive and has a 34 pin interface instead of IDE's 40 pin interface. Thankfully, floppy drives use a 34-pin interface so I just used a floppy cable without a twist in it and cut off the unused connectors.

I managed to find the driver for this on DriverGuide.com. It is called SLCD.SYS and comes with an install program. I was a bit miffed because after installing it the drive didn't work. Reading the docs revealed that the /B switch for the driver's CONFIG.SYS line set the CD ROM's memory I/O address. The installer set this to 340. Apparently it should be set to the sound card's base address plus 10, so after setting it to 230 it worked perfectly.

One issue with the SB PRO, is that it is not MPU-401 MIDI compliant. I had just bought an MT32 synth which requires an MPU-401 interface. The SB16's are MPU401 compliant but they support is quite limited and can cause issues with certain older games, and many of them have a 'hanging note' bug which basically makes an SB16 a poor choice. Instead, I have a Music Quest MPU-401 interface card:

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This card has a DB9 port on the back, and the black adapter converts this to two 5 pin MIDI connectors.
This card also supports MPU-401 'intelligent' mode so gives better compatibility than an SB16.
Roland cards are usually the ones to go for but they seem pretty rare, this is the best I could find.

Anyway, put it all together, and installed DOS 5 on the hard disk.
I decided to go for DOS 5 as its more appropriate for a 93ish machine. DOS 6 came out in 93 but DOS 5 was still more common at the time. There are some subtle differences but overall it does the same things. Main things are the lack of Scandisk (use CHKDSK instead), Defrag and compression utilities.

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Anyway, its all together and working great :D Here's the final product.

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I wish I could have got the cables a bit neater, but with every drive bay filled and all the ribbon cables going everywhere its quite cramped in there. Desktop cases are definitely easier to work on; note the hard drive in the top right. I have to remove the power supply to take out the hard drive o_O


I've been playing Sam and Max and Return to Zork on it; the MT32 really gives the old games a new lease on life :) I hope to get some XWing time in these holidays too :D

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Last edited by DonutKing on 2019-8-08 @ 00:18, edited 2 times in total.
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Re: 386DX40 build

Postby Mau1wurf1977 » 2010-12-29 @ 06:44

Fantastic build!

I like everything about that machine. The case, the board, the choice of video and sound cards, the monitor.

Your choice of parts clearly shows that you have done lots of research! I must say, to me at least, this is the perfect retro 386 machine. 386DX 40 check, SB Pro check, MPU401 check, ET4000 check, MT-32 check.

It's as if you took my wishlist and put it all together for real LOL

If you don't mind and run 3dbench (software and instructions found here: viewtopic.php?t=26175) and post your results.
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Re: 386DX40 build

Postby DonutKing » 2010-12-29 @ 07:37

Heh, glad you like it :)

I ran 3DBENCH and scored 15.3. Judging by your database this is a bit on the low side, although still within expectations....
Here's the entry if you want to add it to the database:
AMD-386DX-40-1-40-Contaq-Contaq 386/'MS-3124'-SIS 85C206-256KB-ISA-ET4000AX-1024KB-DonutKing-15.3

I think I may have to do a little bit of fiddling... I've already set all the RAM timings as tight as I can.
I notice in the manual that it has jumpers to control the ISA bus speed. Its currently set to run asynchronously to the CPU, at 7.2MHZ however you can also set it as a divider. I might try changing this to try and get the ISA bus to run closer to 9 or 10MHz and see if this gives any performance boost.
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Re: 386DX40 build

Postby GL1zdA » 2010-12-29 @ 08:04

Nice build. I like it how carefully you selected components to make it a build for a specific year - I'm usually no that orthodox, especially about storage (HDDs/CD-ROMs).
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Re: 386DX40 build

Postby DonutKing » 2010-12-29 @ 08:12

Well I mainly was curious about how those proprietary CDROMs worked, I think I got that off ebay for $15 or so. So I decided to build a system for it :)
And let's face it, DX40's are a cool little chip ;)

You could argue that 425MB is excessive for that time period but its quiet and seems to work well, and doesn't hit the 504MB barrier so I'm happy with it for now :)
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Re: 386DX40 build

Postby Mau1wurf1977 » 2010-12-29 @ 08:20

That score is perfect!

The idea of that database is really for "reference" and not for overclocking / tweaking. I'm certain that fiddling with your BIOS settings will improve performance, but what's the point LOL
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Re: 386DX40 build

Postby retro games 100 » 2010-12-29 @ 08:33

Congratulations DonutKing! :happy: You have produced another Vogons thread masterpiece! :cool:
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Re: 386DX40 build

Postby Amigaz » 2010-12-29 @ 09:21

Impressive build!

How about making it more impressive by adding a Gravis Ultrasound Classic ;)
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Re: 386DX40 build

Postby DonutKing » 2010-12-29 @ 09:23

Sure, if you wanna tell me where I can get one for less than $100AU plus shipping.....
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Re: 386DX40 build

Postby Amigaz » 2010-12-29 @ 09:27

DonutKing wrote:Sure, if you wanna tell me where I can get one for less than $100AU plus shipping.....


Ebay.de

The usually sell for 30-50 euro
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Re: 386DX40 build

Postby Mau1wurf1977 » 2010-12-29 @ 09:31

DonutKing wrote:Sure, if you wanna tell me where I can get one for less than $100AU plus shipping.....


I have a GUS PnP (not sure which one exactly, it's red and has RAM sticks at the back).

You aren't missing much. IMO the GUS is totally overrated. Games that support MT-32 or General Midi sound better on those cards anyway.

It's only a handful games that use "tracker technology" like pinball fantasies where the GUS sounds better. It's more useful for the "demo scene" which used the cards heavily (e.g. famous second reality demo).

Here are recordings from the game "Extreme Pinball":

GUS: http://www.mediafire.com/?f2ke26be63a67e6

SB16: http://www.mediafire.com/?24by5he6k9ydtfy
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Re: 386DX40 build

Postby DonutKing » 2010-12-29 @ 09:42

Hmmm the only ones I can see at the moment are going for 150 euros... I've been keeping my eye out for a GUS for a while now but I never see any for less than $100AU plus shipping. That's just a bit more than I'm willing to pay for my curiosity.

Having said that, it took me a while to get the MT32 because I grew up with FM synth and didn't know any better :P I'm glad I got it though.

I used to play the hell out of Extreme Pinball :D I actually like the title music... lol
The GUS does actually sound noticeably better IMO
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Re: 386DX40 build

Postby Mau1wurf1977 » 2010-12-29 @ 09:44

For the pinball series the GUS is the card to get. Hands down and no debate LOL
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Re: 386DX40 build

Postby Amigaz » 2010-12-29 @ 09:44

@Mau1wurf1977

True, I only use it for the games that use .mod files for music/sfx in the games where it's superior and it's a must if you're into the demoscene stuff which is something alot of people miss since the music can be stunning in those!
+ the GUS Max, Ace, Classic just sits in your system not taking any resources which are software controlled so it doesn't hurt having it installed...the coolness factor increases with how many soundcards you can stuff in your system :D
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Re: 386DX40 build

Postby Mau1wurf1977 » 2010-12-29 @ 09:57

The GUS certainly has a high "coolness" factor LOL

It was a short lived and IMO niche card which makes it rare and pricey... Definitely worth hanging onto...

I'll dig up a pic of mine...

EDIT: Here we go...

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When I got it, it took me ages to figure out how to initialize it into "GUS Classic mode" so it would work with DOS games. And people say Creatives software is confusing LOL
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Re: 386DX40 build

Postby retro games 100 » 2010-12-29 @ 10:05

That's a GUS PnP, more aimed at Windows 95. A GUS "classic" sound card is better for old DOS games.
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Re: 386DX40 build

Postby Mau1wurf1977 » 2010-12-29 @ 10:12

retro games 100 wrote:That's a GUS PnP, more aimed at Windows 95. A GUS "classic" sound card is better for old DOS games.


Yea this card is both LOL

I figured it out eventually. Just needed some GUS drivers and run a single batch or initialization file and BAM you have a GUS classic.
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Re: 386DX40 build

Postby Amigaz » 2010-12-29 @ 10:14

@Mau1wurf1977

GUS PnP, use to have 4 of them (lol) until recently when I did my mega-clearout-sale of spare vintage PC items
These fetch quite high sums nowdays....but not close to the insane high sums the GUs Extreme sells for :P

I also scratched my head for some time before I figured out how to configure the card for DOS use...didn't know I had to use the CD as well, doh! :D
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Re: 386DX40 build

Postby Amigaz » 2010-12-29 @ 10:15

Mau1wurf1977 wrote:
retro games 100 wrote:That's a GUS PnP, more aimed at Windows 95. A GUS "classic" sound card is better for old DOS games.


Yea this card is both LOL

I figured it out eventually. Just needed some GUS drivers and run a single batch or initialization file and BAM you have a GUS classic.


And the GUs PnP has clearer output :)

didn't you just use the install floppy and the CD with the patches?
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Re: 386DX40 build

Postby retro games 100 » 2010-12-29 @ 10:37

Re: GUS PnP "converted" to a GUS Classic. Is it possible to use the 1 meg in size PPL (Pro Patch Light, I think it's called) patches, on a GUS PnP in pure DOS? I thought that the GUS PnP Pro sound card had 512K of onboard memory, which you could use in GUS Classic mode, but the full 1 meg music patches (such as PPL) could not be used in pure DOS mode, because the PnP card did not have enough on board RAM.

I know you can add 8MB of additional RAM, which makes a total of 8.5MB, but the additional 8MB of RAM could only be used in Windows.
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