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#1 2016-02-09 09:07:39

iMic
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Microbits Cyrix 6x86 / Am486 PC Build

While I have a fondness for vintage Apple machines, classic PCs are a completely different beast. There's a world of variation in components, configurations and some of the most unusual and obscure hardware was developed for the IBM compatible that it makes each machine unique with its own distinct character.

I'd been searching for an old machine to build for some time, but finding anything 386/486/Pentium is becoming ridiculously difficult. Most of these machines, common as they once were, have been recycled for scrap metal over the last two decades. But I have one, and it sure is an interesting beast.

IMG_0264.jpg

This machine was assembled by Microbits, an Australian assembler of PCs based out of Adelaide. The company was established in 1983 and went into liquidation in 2006. It's a Cyrix 6x86 machine based around an Octek motherboard. As far as condition goes I would consider it fair, but incomplete. Some restoration is required.


What it does have is an impressive selection of cards.

IMG_0267.jpg


This system contains an ISA 3Com EtherLink network card, followed by a later revision Creative Sound Blaster 16 ISA. Across to the PCI slots, this machine includes an S3 Trio 64V2/DX and a Creative 3D Blaster Voodoo 2 CT6670. With enough slots remaining to load a few extra cards in there as well.

I'm aware the CPU is missing. I removed it for cleaning; it's currently sitting on my desk.

The machine lacks any kind of Floppy Disk based storage, something I intend to rectify soon with a 3.5" and 5.25" drive attached to the onboard controller.

No hard drives either, but I have relatively era-appropriate Western Digital Caviar 2700 730MB and Caviar 21200 1.2GB drives that make all the right noises. I'm positive I have an old <2GB Quantum Fireball ATA around here as well. If I wanted to go as vintage as possible I have a Seagate ST351A/X 40MB Stepper ATA around here too, but capacity wise I think that may be a little too small.

Most notably though, the machine is missing its power supply. So I'll be on the hunt for an AT PSU that can be recapped and installed in the currently vacant spot in the back case.

Not sure of operating system, but I think a combination of DOS and Windows 3.11 needs to happen.


Still haven't decided what purpose this machine will serve if any, but even so it's an interesting piece of kit.


Resident Professor of Alternative Methodology
Faculty of Macintosh Restorations & Modifications - "It works, let's fix it!"

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#2 2016-02-09 18:02:35

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Re: Microbits Cyrix 6x86 / Am486 PC Build

Too bad I'm on the other side of the planet, because my collection is overflowing with older x86 PC stuff like this, almost all of it just parts.  Getting hold of the drivers for hardware of this vintage is going to be the greatest challenge because so little of it was ever incorporated into the operating systems of the day.  Most it just kinda faded away as the companies disappeared.  The fact it's a Socket 7 generation gives more hope because it's still relatively recent in vintage terms, and at least you can be certain of being able to boot a version of DOS successfully.  I appreciated the Cyrix processors only for the novelty factor of being less common.  They generally didn't inspire much 'awe' in the performance department.

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#3 2016-02-09 18:26:41

Eudimorphodon
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Posts: 524

Re: Microbits Cyrix 6x86 / Am486 PC Build

iMic wrote:

Not sure of operating system, but I think a combination of DOS and Windows 3.11 needs to happen.

Windows 95 is probably more authentic chronologically for a Socket 7 system. (Particularly for a 6x86, which didn't debut until 1996.) But, well, it's Windows 95.

I always thought the 6x86 was sort of an underrated chip. Yes, its floating point performance sort of blew chunks but for integer mixes it was super quick for the era. The first machine I ran Linux on full-time was a 6x86 and it did a fantastic job. Since you didn't include a picture of the CPU we can't tell; is yours the original FLAMING HOT model or the improved 6x86L? Mine was the latter, one of the IBM label chips.


Flap Different.

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#4 2016-02-10 00:18:47

iMic
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From: Adelaide, Australia
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Re: Microbits Cyrix 6x86 / Am486 PC Build

Eudimorphodon wrote:

Since you didn't include a picture of the CPU we can't tell; is yours the original FLAMING HOT model or the improved 6x86L? Mine was the latter, one of the IBM label chips.

It's a Cyrix 6x86MX PR200 (150MHz). Non-L version.


Turns out this machine wasn't built with the Cyrix / Octek combination in place, because we found the original motherboard and processor that came in this machine. Now I'm considering whether to swap the factory board back in. If I do, I'll keep the Octek board and Cyrix processor for another build.

The factory board is a Dataexpert ExpertBoard 8049 Rev. A series with an AMD Am486 DX4-100 processor.

IMG_0276.jpg


Managed to find a factory standard 5.25" disk drive as well.

IMG_0274.jpg


Resident Professor of Alternative Methodology
Faculty of Macintosh Restorations & Modifications - "It works, let's fix it!"

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#5 2016-02-10 00:45:08

ClassicHasClass
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From: Electron Alley
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Re: Microbits Cyrix 6x86 / Am486 PC Build

I didn't mind the Am486, but the Am5x86 was much better in nearly every respect. The downside is it's still a 486, so certain Pentium-expecting applications (Quake ahem) won't run on it.

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#6 2016-02-10 05:13:51

MacOS Plus
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Re: Microbits Cyrix 6x86 / Am486 PC Build

Eudimorphodon wrote:
iMic wrote:

Not sure of operating system, but I think a combination of DOS and Windows 3.11 needs to happen.

Windows 95 is probably more authentic chronologically for a Socket 7 system.

Agreed, and far more likely to have drivers available or included in the Windows installer media.

  I remember we had a DX4-100 in our primary home PC for a while.  It was quite a work-horse and also a welcome leap over the 486DLC-in-a-386-board it replaced.  Having run the DX4 at 3-times 33MHz bus it always seemed odd to be calling it a "DX4" - more like 'DX3'.  Remember VL-Bus?  Fun times!

  If you use that DataExpert board, get rid of the soldered CMOS battery ASAP.  They always end up leaking and causing a whole bunch of rot on the PCB.  By this point in its life it's probably dead anyway.  It appears from your photo that the board has the usual four-pin header for an external battery pack - you'll definitely want to put one together for that and stick to common AA cells.

  Every black-front/red-LED floppy drive I've ever seen has been double-density only.  If so with yours it's a bit behind the time period, but also much less useful than a high-density drive.  Almost every high-density drive ever had an amber LED.  (Although I did have a couple odd-balls, one red and one green.)

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#7 2016-02-10 05:32:18

Eudimorphodon
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Registered: 2014-09-02
Posts: 524

Re: Microbits Cyrix 6x86 / Am486 PC Build

Actually in this day and age I'd rather have an elderly PC with  double-density 40 track 5.25" drive than an HD one, because the former is more generally useful for doing data transfer to other old computers. (Various CP/M formats, TRS-80, etc. Find a Catweasel or similar and the horizons expand further. Sure, you can mostly do the same with the 80 track drive but the narrower tracks can cause problems.)


Flap Different.

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#8 2016-02-10 05:59:58

MacOS Plus
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Re: Microbits Cyrix 6x86 / Am486 PC Build

Very true, although I figured he would be more likely to make use of high-density disks for setting up the PC to begin with.  On the other hand, by that time most things on floppy were in 3.5" disks and CD-ROMs were taking over.  I suppose I should ask the question then of iMic, did you have any particular task in mind for this machine?  (Or is it just for re-living the experience of cursing at Windows 95? wink)

  There is a good reason why I kept all my working double-density drives though, as you noted.  I even have a 720k 3.5" drive in my Turbo XT.  If you want to go more unusual, somewhere around here there is an IBM 2.88MB Thinkpad floppy drive and also a couple of 8" floppy disks I hung on to pretty much only for novelty's sake.  In a similar vein, we used to have a bunch of 20MB Bernoulli Box gear, but gave it all away after it wouldn't play nice with the Turbo XT and a number of the cartridges wore out.  Seriously, those were pretty much the bulkiest 'floppy disks' ever.

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#9 2016-02-10 09:03:18

iMic
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From: Adelaide, Australia
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Re: Microbits Cyrix 6x86 / Am486 PC Build

MacOS Plus wrote:

If you use that DataExpert board, get rid of the soldered CMOS battery ASAP.  They always end up leaking and causing a whole bunch of rot on the PCB.  By this point in its life it's probably dead anyway.  It appears from your photo that the board has the usual four-pin header for an external battery pack - you'll definitely want to put one together for that and stick to common AA cells.

The battery is leaking, but it doesn't appear to have corroded anywhere down to the PCB so far. I'll desolder it before it becomes a problem.


MacOS Plus wrote:

Every black-front/red-LED floppy drive I've ever seen has been double-density only.  If so with yours it's a bit behind the time period, but also much less useful than a high-density drive.  Almost every high-density drive ever had an amber LED.  (Although I did have a couple odd-balls, one red and one green.)

This drive is a TEAC FD-55GFV. From a couple of quick searches it looks to be a DS/HD 1.2MB drive. Turns out it was also available in beige plastic which would have worked better in this case, but I don't mind.


MacOS Plus wrote:

Very true, although I figured he would be more likely to make use of high-density disks for setting up the PC to begin with.  On the other hand, by that time most things on floppy were in 3.5" disks and CD-ROMs were taking over.  I suppose I should ask the question then of iMic, did you have any particular task in mind for this machine?  (Or is it just for re-living the experience of cursing at Windows 95? wink)

My first computer ran Windows For Workgroups 3.11 and MS-DOS 5. Making it run those systems and some of the older applications would be priority number one. Next would be the ability to use some older and interesting peripheral cards, primarily under DOS. Gravis Ultrasound, Roland SCC-1 MIDI and AdLib come to mind. Otherwise it won't serve any particular task.


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Faculty of Macintosh Restorations & Modifications - "It works, let's fix it!"

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#10 2016-02-10 11:31:52

LCGuy
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From: Sydney, Australia
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Re: Microbits Cyrix 6x86 / Am486 PC Build

I'd probably leave it with the SB16 - its not a bad card, and is probably the best supported card for DOS games.

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#11 2016-02-10 16:27:10

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Re: Microbits Cyrix 6x86 / Am486 PC Build

The really early sound cards would be fun.  I've got a huge variety of cards all the way back through the original 8-bit SoundBlaster in the original packaging.  It was a noisy piece of crap but at least had more features than the AdLib.  I also have a 1990 Adlib - such a simple creature, and they thought so highly of themselves that they burred-off the lettering on the main chip.

  I plan to try to set up some of my old cards as stand-alone MIDI instruments so I can toy around with the synth sounds in my studio using a later machine as the sequencer.  Initially I'm favoring the SoundBlaster AWE32 and 64 cards because of the expandable RAM for sound fonts, but some of the older cards may still be useful where a 'cruder' sound is what I'm after.  Whichever ones have the least noise contamination and actually play in stable MIDI sync are going to win-out.  I have a number of the game port MIDI breakout cables and also one little keyboard that connects dedicated via the game port.

  If you find any good sources for drivers and utilities for the vintage PC sound cards, please let me know.

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#12 2016-02-10 19:14:55

Eudimorphodon
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Registered: 2014-09-02
Posts: 524

Re: Microbits Cyrix 6x86 / Am486 PC Build

iMic wrote:

The factory board is a Dataexpert ExpertBoard 8049 Rev. A series with an AMD Am486 DX4-100 processor.

Wow, a PCI 486 board, don't see those very often.

(A few months ago I found VLB board likewise fitted with an Am486DX4-100 that looked almost precisely like that one other than the slot layout at a garage sale for fifty cents in its original box and anti-static envelope, even had the padded jewel box for the CPU rattling around inside. Ended up flipping it over on the VCF along with some random ISA cards.)

Personally I'd probably stick with the 6x86, I remember those PCI 486 boards being a little bit iffy. What chipset is the Socket 7 motherboard, something decent or is it a gawshawful PC-CHIPS monstrosity?


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#13 2016-02-10 23:39:29

iMic
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Re: Microbits Cyrix 6x86 / Am486 PC Build

LCGuy wrote:

I'd probably leave it with the SB16 - its not a bad card, and is probably the best supported card for DOS games.

But then I wouldn't have the chance to experiment with other cards. That and I can swap cards in and out at will.


MacOS Plus wrote:

If you find any good sources for drivers and utilities for the vintage PC sound cards, please let me know.

VOGONS Vintage Driver Library. Their selection is fairly impressive. I have some of the discs for the cards in this machine already as well, DOS drivers for the Voodoo 2 and so on.


Eudimorphodon wrote:

Personally I'd probably stick with the 6x86, I remember those PCI 486 boards being a little bit iffy. What chipset is the Socket 7 motherboard, something decent or is it a gawshawful PC-CHIPS monstrosity?

In terms of architecture I can't help but feel there is a distinct rollover point between the 486 and 5x86 (Pentium) architectures. I could probably still source a Pentium machine from somewhere if I looked hard enough, but 386/486 kit is seemingly much harder to find. So I would much prefer to build around the 486, especially considering this is the factory board and CPU for this machine, and assemble the Cyrix machine inside another case.

Fairly confident the Socket 7 board is an Octek Rhino 15, which would make it an Intel chipset based board. Not my photo, but it looks identical.


Placa_Base_Socket_7_OCTEK_Rhino_15_REV_1_12_car.jpg


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Faculty of Macintosh Restorations & Modifications - "It works, let's fix it!"

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#14 2016-02-11 00:02:28

Eudimorphodon
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Posts: 524

Re: Microbits Cyrix 6x86 / Am486 PC Build

iMic wrote:

In terms of architecture I can't help but feel there is a distinct rollover point between the 486 and 5x86 (Pentium) architectures. I could probably still source a Pentium machine from somewhere if I looked hard enough, but 386/486 kit is seemingly much harder to find. So I would much prefer to build around the 486, especially considering this is the factory board and CPU for this machine, and assemble the Cyrix machine inside another case.

Well, that's the thing though; having PCI sort of makes that 486 board neither fish nor fowl. Granted it's probably not really going to be *that* much an issue if you stick with ISA for everything other than the video card but for a *strict* 486 DOS-era experience I'd probably prefer a VL-Bus board. You'll definitely want to choose your video card carefully if DOS is going to be the primary focus.


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#15 2016-02-11 01:54:28

iMic
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From: Adelaide, Australia
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Re: Microbits Cyrix 6x86 / Am486 PC Build

A VL-bus board would be preferable but in this case I'll have to make do. The 486 board inches ever so slightly closer to the configuration I'm after. And I used to build these ISA/PCI hybrid machines in my earlier years so I consider it a bit of fun.

Bonus points if the board has an AMIBIOS, because I haven't seen that startup screen in years, but I'll manage with an Award.

I have some selection when it comes to video cards. It has the S3 Trio 64V2/DX in there, but I have the option of an ARK Video card and a Trident as well, both PCI. No ISA video hardware at this point.


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Faculty of Macintosh Restorations & Modifications - "It works, let's fix it!"

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#16 2016-02-11 02:16:44

LCGuy
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From: Sydney, Australia
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Posts: 810

Re: Microbits Cyrix 6x86 / Am486 PC Build

iMic wrote:

Fairly confident the Socket 7 board is an Octek Rhino 15, which would make it an Intel chipset based board. Not my photo, but it looks identical.

I've got one of those somewhere. Not a bad board.

Funnily enough I prefer vintage PCs that have an Award BIOS, because I remember seeing that startup screen on the PCs at school in Grade 6/7.

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#17 2016-02-13 16:51:11

iMic
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Re: Microbits Cyrix 6x86 / Am486 PC Build

Performed some preventative maintenance on the 486 board this afternoon. Desoldered the NiMH 3.6v battery from the board. Was somewhat concerned when I looked at one particular trace underneath the battery, but it still has perfect continuity between the Winbond IC and the onboard Floppy Drive header that it connects to. If the drive interface ever stops working I'll run a patch across the board.

IMG_0297.jpg


I cleaned the case inside and out. I was rather impressed at how clean and unmarked the case was underneath the layers of sticker residue and tape. With the machine relatively clean I performed a test fit of the drives and some other components. The black 5.25" drive actually matches the aesthetic of the case in the lower bay, continuing the black band across the fascia.

The 3.5" floppy drive is mounted with two screws on one side, but the other side used some kind of slide in rail which has since been lost. Not sure how to address this, because while the drive can be installed without it, it causes some alignment issues with the front case plastics. I may have to look into having a replacement rail designed and 3D printed if I can't find a suitable replacement.

IMG_0315.jpg


The Octek motherboard also has a connection for an ATX board, so I was able to start testing some components of the system despite the fact I'm still looking for a suitable AT replacement. The Cyris 6x86 processor is a screamer, or at least its cooling fan is. Talk about loud! But it sounds rather pleasant and appropriate for a Socket 7 era machine, and I'm sure the case lid would dampen the noise somewhat as well.

I noticed the optical drive is a much later replacement Hitachi DVD-ROM from a Power Mac. Something I would like to address, after all DVD-ROM drives weren't around during the 486 era, but I still consider this a lower priority at the moment.

IMG_0301.jpg


Lastly the Western Digital Caviar 2700 730MB hard disk drive was scanned and tested. After some messing around with jumpers it detected without issue as the primary master and completed a track and block integrity scan without issue. I didn't perform a format this time, I figured I would investigate this further and if a low level format is required I'll wait until it's paired with the correct motherboard and drive controller first so I can set the correct interleave.

IMG_0298.jpg


Resident Professor of Alternative Methodology
Faculty of Macintosh Restorations & Modifications - "It works, let's fix it!"

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#18 2016-02-13 20:19:57

ClassicHasClass
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From: Electron Alley
Registered: 2014-05-26
Posts: 1,085
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Re: Microbits Cyrix 6x86 / Am486 PC Build

Hey, careful of that warranty sticker. You might need to bring it back to the shop.

(I have an AppleCare sticker on the back of my Mac Plus. I'm tempted to bring it into the Genius Bar just to see if those young whippersnappers know what one is. Related: Get off my lawn.)

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#19 2016-02-13 23:55:53

LCGuy
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From: Sydney, Australia
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Re: Microbits Cyrix 6x86 / Am486 PC Build

Meanwhile I still need to fill out the warranty card for my 8*24 video card...

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#20 2016-02-14 15:54:32

jt
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From: Bermuda Triangle, NC USA
Registered: 2014-05-21
Posts: 1,391

Re: Microbits Cyrix 6x86 / Am486 PC Build

iMic wrote:

The black 5.25" drive actually matches the aesthetic of the case in the lower bay, continuing the black band across the fascia.

That was my first thought, couldn't get the image of the BLUE SCREEN OF DEATH with a black "racing stripe" out of my head. lol

iMic wrote:

Fairly confident the Socket 7 board is an Octek Rhino 15, which would make it an Intel chipset based board. Not my photo, but it looks identical.

Are you inferring an earlier model ID of your DIP ROM board from the later SMT ROM board?

Cool project, reminds me of my DELL Dimension 4100/Win98 rebuild. I still haven't hooked it up with the ROM burner. hmm

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#21 2016-02-21 06:18:10

iMic
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From: Adelaide, Australia
Registered: 2014-05-12
Posts: 878
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Re: Microbits Cyrix 6x86 / Am486 PC Build

Project remains at a standstill at the moment. The screws that hold my head on needed tightening, so I've been spending time away from home trying to get things back in order.

Haven't managed to source an AT PSU so far. Had someone offer one for $10, but pickup was extremely far away. Another offered one for $20 but hasn't contacted to set a time and date to collect, and another was closer but wanted $80 for it untested. Some members over at the OCAU forums think I should go the ATX to AT converter route, but if I can maintain some level of era-authenticity and rebuild a standard AT with new components that would be a better choice in my book.

Still haven't sorted the 3.5" FDD mounting rail. Not sure how to tackle that one. I considered possibly also folding a bracket out of thick sheet metal if nothing else, or having a thick piece of aluminium cut, polished and drilled to mount to that side of the drive. All it needs to do is slide into the channel to keep it lined up with the front bezel.

I remembered last night that I have a Mitsubishi DiamondData CD-ROM drive that would probably suit this machine somewhat better than the DVD-ROM that's in there, but I can't remember where I left it. Presumably in a box in storage somewhere.


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Faculty of Macintosh Restorations & Modifications - "It works, let's fix it!"

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