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My 8086 Deskpro is on its last legs.....Upgrade time!

Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
My 8086 Deskpro has been acting flakey and has a few issues.

Last night I powered on and it popped a tantalum capacitor, not the first one so that by itself is not a big deal or hard to fix but it has been giving me issues for the past couple of years.

Has a dead ISA slot and one that sometimes works and sometimes does not.

It's at the point that I sometimes dread turning it on because of the ol "well what next will go wrong". :(

Current Specs: 8086 Compaq Deskpro 8086

V30 CPU
8087 co-processor.
640k of ram
2mb Rampage card
3Com 903 8 bit eithernet card
XTIDE V1, bought as a kit and assembled it years ago.
Logitech bus mouse card
Microsoft bus mouse
Original Amber monitor and dual mode video card
16 bit MFM controller card that lets me use a 1.44 mb floppy and the original 360K floppy drive.
212 MB IDE hard drive.

First off I am not looking to add a X570 motherboard/3700X cpu/ 64 Gigs of ram/GTX2080 to it.;)

I already have tons of Pc's from a generic 8088 to a few Dual and Quad cpu Xeon servers, a couple of 486's, Pentium 75, 100, 133, K6, K6-2, Pentium 3, Athlon 64, Phenom 2 and on and on......come to think of it I really have too much crap but i'm single LOL.

I love that pc, been having it for decades so I want to keep the "feel" of it but get rid of the unreliability, I want to keep the feel and sounds its been having for decades.

I'm not interested in gaming on it so really no graphic intensive programs at all, mostly just text stuff.

So what to do?

I found a NOS motherboard, but i'm worried about the reliability of it.

Thought about a Deskpro 286 motherboard swap, then a 386 Deskpro board swap.... the 286 board would be just as old and the 386 is almost as old and has its own issues with the that design.

I want to keep Compaq DOS 3.31 and 5.0 when I feel the need to swap hard drives.

I want to be able to plug in the original MFM 20 MB hard drive from time to time.

I love the Amber monitor.

Keyboard is ok, i'm used to it.;)

Keep the bus mouse.

So I'm defiantly thinking of swapping out to a newer motherboard but new enough to be more reliable but still has only ISA slots, as I want to be able to use my isa cards, and hopefully with a cr2032, or a separate battery holder not a barrel battery.

Yes the power supply is non AT standard, also the motherboard is defiantly not standard either.

The power supply, I have three or four spares including one thats dead that i'm thinking I can easily mount a AT supply in it since its big enough and I could wire it to use the original power switch.

ATA motherboard mounting is defiantly doable.

So i'm thinking of a newer 386 or 486 board, only ISA no PCI slots, slow 386 or 486 with turbo and cache off at all times.

4 MB at most of ram.

Reuse the XTide card, bus mouse card, network card, occasionally use the MFM hard drive, I have both 8 and 16 bit controller cards, amber monitor I only ever used it on the higher resolution so a replacement video card that will drive it at the higher res is would I would want, I do not think the dual mode card would work correctly but I would give it a shot to see.

What about the keyboard connector? Deskpros that I have seen come with either a plastic one soldered on the motherboard at the front of the motherboard, or like mine a five pin header and a connector thats bolted to the case. Thats a easy fix as I can remove the replacement board keyboard and solder a jumper harness directly to the motherboard and run it to the original keyboard connector on the front of the case.

Also I have seen a 486 motherboard with a 5 pin keyboard header in almost the same spot as the original 8086 board.

So I guess I really need just to find the right motherboard, yes I know there were upgrade boards to retrofit the early deskpros to faster cpu's but I have only seen them in ads but they are old and weird too.

Any suggestions on a board?

Yea I also realize any 386 or 486 board I find is old also but at least they will be a few years newer and maybe give the old Deskpro a few more years of life.
 
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Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
couple of pics:





Original board compared to a tiny 486 board, the round stand offs could easily be re positioned for a standard ATA pattern.
 

resman

Experienced Member
Joined
Jan 1, 2014
Messages
475
Location
Lake Tahoe
I have a Deskpro 286 (same case configuration as the original Deskpro) with a dead MB and also looked for replacement MBs. Nothing came close. The way the drive cage is arranged and the openings for the slots just doesn't match anything else. Not to mention the power supply differences. Best to try a replacement Compaq MB. A 286 would give you a performance boost, but I like the nonstandard configuration of the 8086 (I have two).

Edit after seeing Klee's pics. I guess I have a MB to search for...
 

Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
See the round stand off's? They are held on by one rivet and one tab, so they could be moved where needed and new holes drilled and either rivets or short screws. Or even maybe just epoxied in place.

The only real issue is the tab at the rear of the case near the monitor connector is where one of the two screw that holds the original motherboard in would need to be bent down, also I would need to get creative where the motherboard standoffs at the rear of the board by the isa slots would need to be.

The power supply's are massive, could be easily gutted and a newer smaller at supply could be mounted inside.
 

Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
A generic 8088 motherboard.




Pic from a few years ago, sure has yellowed a bit since then.

 
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resman

Experienced Member
Joined
Jan 1, 2014
Messages
475
Location
Lake Tahoe
A 286 or 386 is just too fast for that keyboard ;-) And depending on BIOS, may not like it. My Deskpros are very similarly configured to yours (except I haven't found a network card to work with it). To me it really hits a nice performance mark - not painfully slow like a 4.77 MHz 8088, but not too fast to mess up that early '80s retro vibe. Even my Deskpro 386/25 is too fast when only 16 bit goodness is desired. So, yeah, my vote is for a NOS 8086 MB.
 

Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
Too late, I already gambled and ordered a 486 board off ebay.

I have used regular XT keyboards with my deskpro, I also have one keyboard with alot of sticking keys that has a at/xt switch on it, will have to take it apart to see whats in it.

Made a lowball offer and the seller took it, was not expecting that. LOL

Has a 486 sx on a unusual package, maybe a Intel Underdrive cpu? LOL





Has a keyboard header in the right place.



Its one of those spur of the moment purchases and I used money I already had in my payapl account, I may or may not regret it. LOL

Seems to be in excellent shape, will test it out in as regular at case before I even attempt to mod the Deskpro case.
 
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Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
I cleaned the ISA slots on the original 8086 motherboard, cut out the exploded capacitor and put it back together.

The dead slot is now working, one of the four molex connector ports on the motherboard is dead now but the other three still work.

So the Deskpro 8086 is working again.

Doing a Checkit pro quick test right now just to stress it a little.

I need to familiarize my self with it again, don't remember what software I had installed but I at least its working again as it was.

Mtcp needs to be updated, still running the version from 2013.

When I get the 486 board i'll put it in a AT case and test it out and then decide what to do.

I also have a newer version XT-IDE card to install, been wanting to put the V1 card in my 8088 generic pc for a while now.

So things are undecided for now as what direction I will end up going, just depends on the 486 board being good and if it looks like it can be mounted and/or the 8086 board working ok.
 
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resman

Experienced Member
Joined
Jan 1, 2014
Messages
475
Location
Lake Tahoe
I cleaned the ISA slots on the original 8086 motherboard, cut out the exploded capacitor and put it back together.

The dead slot is now working, one of the four molex connector ports on the motherboard is dead now but the other three still work.

So the Deskpro 8086 is working again.

Doing a Checkit pro quick test right now just to stress it a little.

I need to familiarize my self with it again, don't remember what software I had installed but I at least its working again as it was.

Mtcp needs to be updated, still running the version from 2013.

When I get the 486 board i'll put it in a AT case and test it out and then decide what to do.

I also have a newer version XT-IDE card to install, been wanting to put the V1 card in my 8088 generic pc for a while now.

So things are undecided for now as what direction I will end up going, just depends on the 486 board being good and if it looks like it can be mounted and/or the 8086 board working ok.

Fantastic! Glad you revisited the 8086. Having said that, you got me interested in dragging out some old 486 MBs I had in the pile of misfit hardware. One looks like it may fit in the 286 Deskpro case with some work. It's functionality is questionable, but perhaps worth a little time trying to revive it.
 

Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
Got the 486 motherboard in, it looks brand new !!

The battery was dead as expected but it had just started to leak and only corroded the negative pin of the battery just a tiny amount with ZERO damage to the board so I cut it off.

Will use the other battery connector with a remotely mounted AA battery holder.

$48.00 with cpu and 4 mb of ram with free shipping.

As long as it will boot i'll be super pleased.

Will post pics later.
 

Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
Installed the 486 board in a generic AT case, installed a old Tandon dual mode video card and a old monochrome monitor, keyboard, speaker connector and power connectors.

And it boots!!






Booted up with a 360K MSDOS 6.22 dos boot disk and let it just sit for a while and it works fine.

Have not stressed it yet at all.
 
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Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
Pics of the board.

Battery area, only minor staining and zero damage.


Whole board.


All important second keyboard connector in the same location as the original 8086 motherboard but since the 486 board is shorter i'll need to use longer wires but I wont have to hack or remove the standard rear keyboard connector.


Cpu , should be able to set it to 16mhz.
 
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Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
The Tandon Dual Video III card does MGA and CGA through jumpers, might end up installing a ATI VGA Wonder XL since that would give me a ton of flexability with displays.

Why 16 Mhz? I want to keep the feel of the original deskpro 8086 and 16mhz and combine that running without turbo it should slow it down decently.

My goal is to have the same look and feel of the original 8086 deskpro when I want that but also give me alot more capability that the 8086 could never have.
 
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Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
Well just tried the original Compaq Deskpro keyboard and not surprisingly it does not work. I have been checking out some XT to AT keyboard converter options online so its doable.
 

Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
I was reading an older post on another forum about running 486 slower than the rated speed using undocumented jumper positions, I saw one post that one poster was able to run his at 8 mhz then at 4 mhz. LOL :D

I was shooting for 16 mhz but if it will run 8 mhz thats the stock speed of the deskpro and that would be perfect.:cool:
 

Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
Removed the 8bit floppy isa card and XT-IDE and installed a 16 bit floppy and IDE controller but it did not work.

Gave a hard drive and floppy drive controller error.

Turns out in the bios one setting was CLK2IN/5, with the 50 mhz crystal on the motherboard that means the isa was running a 10 mhz and the controller did not like that speed, so I changed it to CLK2IN/6 to set it at 8.33 mhz.

Now it works!

Controller is a Pine Technology PT-606E.

I'm planning on using it as just a floppy controller and disabling the IDE controller and using the new XT-IDE card that I have.

But since I am planning on running IDE drive of less than 512 mb I may just use the PT-606E if my tests shows it to be faster than the XT-IDE.
 

Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
Some more testing:

This 486SX-25 is no speed demon so its perfect for what I want. :D

Using a program called mips.exe with the turbo button off its about as fast as a 386 with a score of 3.04 and with the turbo button on the score is 4.82 which is about equal to a 8 mhz 286. LOL

So it looks like I wont have to mess with the cpu freq jumpers at all.

I was worried if it was too fast I would lose the "feel" of the original 8086 performance, so I'll just either put a jumper and have the slower speed all the time or more likely i'll mount a switch somewhere thats not noticable.

Now it seems I will have a little more performance than the V30 8086 cpu with all the advantages of a 486.

Now I wont be limited to just DOS, 8086 Xenix or Minix 1.5 -2.0 and others.

I'll be able to run more advanced os's on it even at slow speeds.

So far i'm loving this motherboard, its exactly what I was looking for. :cool:
 

Klee

Experienced Member
Joined
Dec 24, 2010
Messages
200
I received the ATI VGA Wonder XL, hopefully I can install it this weekend and get rid of that old blurry green monochrome monitor.
 
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