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Thread: Compaq Portable III Restoration Complete!

  1. #1
    Join Date
    Apr 2013
    Fort Worth, TX

    Cool Compaq Portable III Restoration Complete!

    I thought some of you might be interested in my Compaq Portable III restoration log!

    I picked up this machine a few months ago for $10 from Craigslist. Ironically, the seller operated a computer repair shop, and was unable to get it working. The computer was in very good condition, but the CMOS battery was long gone, and the keyboard cable rubber was crispy and rotten.

    CMOS Battery Repair
    Normally the CMOS battery death just causes the computer to repeatedly annoy you with the date and time, but with the Compaq, all settings are lost. This means that the hard drive settings are lost, and therefore the machine will no longer boot to anything other than a floppy disk.

    The CMOS battery was a small 1.5V x 2 battery pack, with the two wired in a series. Since the battery is lithium, this allowed me to solder in a good old CR2032 with holder, making future battery swaps easy. The original clamp used to hold the old battery in place fit perfectly over the new holder, keeping the battery secure. A dab of hot glue was added for insurance .

    Floppy Woes!
    The Compaq does not have any other method of accessing the BIOS configuration other than their good old setup disk. Fortunately, this image is available to download online. Once I wrote my own 360K copy, I attempted to boot the disk. Nothing! The drive motor that moves the head was not functioning. I connected my known working drive and proceeded to configure the BIOS. I set the floppy disk to 1.44 MB (which it supports, surprisingly), as I had an upgrade in mind.

    I purchased a new in box Sony floppy drive manufactured in 2006, along with a tray allowing 3.5 devices to be installed in a 5.25 bay. Since the drive bays in the CPIII are about 1/2 more narrow than a normal 5.25 bay, I needed to make my own faceplate. A 5.25 to 3.5 faceplate, a dremel, and a few hours later, this was the result!

    It worked surprisingly well, and looks great in the CPIII (and I don't have to use 5.25 disk anymore!)

    Keyboard Cable

    The CPIII's keyboard cable is notorious for dry rot. In fact, I have not seen one (with original cable) that is not rotten. This was high on the priority list of repairs. I rummaged through the piles of old keyboards in the trash bin at work, and found a cheap AT-style keyboard with the large DIN connector. Since it was missing keys, I didn't feel bad about sacrificing it for it's keyboard cable. Disassembling the Compaq's keyboard was more of a chore than I imagined. You need to carefully remove about 15 keys to access the screws holding the unit together. Once disassembled, you have to be extremely careful when removing the PCB as to not lose the key rubber pads.

    I traced each wire on the old cable, to see which pin on the DIN connector it corresponded with. This allowed me to trace the same wires on the new cable and solder the wires into the proper location. This is where a multimeter is essential! Once finished, it all went back together nicely and worked great.

    All in all this was a fun project! I hope I may be able to assist anyone else trying to restore one of these. I am happy to be able to save another one of these cool machines from entering the landfill.

    If you are having trouble writing the setup disk image I have the raw files that can be simply copied to any disk!! Just shoot me a message if you need them.

    Now on to my Powerbook 100 restoration!
    Last edited by 68k; May 7th, 2013 at 10:26 PM.

  2. #2
    Join Date
    Jan 2012
    Raleigh, NC, USA


    Very nice! Thanks for sharing the pictures.


  3. #3
    Join Date
    Mar 2012
    Cincinnati Ohio


    Love seeing these Compaq Portables threads popup. This is probably my favorite vintage computer just because it's so odd looking.
    This space intentionally left blank [ ].

  4. #4


    Nice informative thread. I have Compaq Portable III. The battery, hard drive and floppy are fine - but the keyboard cable is disintegrating. Every time I move it, more pieces flake off. I've never seen such a shoddy cable.

  5. #5


    Excellent job!Very nice pictures!!

  6. #6
    Join Date
    Mar 2011
    Blog Entries


    Job well done! My Portable III had a DS1287 battery in it. It was socketed in, so that took some of the effort out of replacing it. The keyboard cable on mine suprisingly hasn't rotted yet. The one on my SLT 386s/20 however, is rotting quite a bit and will need replacing soon.

    (Ford Simulator is also one of my favorite games.)

    Looking for a Gateway 2000 G6-333 - my first computer.

  7. #7


    I just recently got a Compaq Portable III, and I have to admit, finding posts like this was why I bought it. I've replaced the gas plasma display with one from a parts machine, and next on my list is the 3.5" floppy drive swap (the 5.25" drive doesn't work consistently). Is that fairly straightforward, or am I going to have to hook up another 5.25" drive to boot the setup disk and then tell it I have a 1.44MB floppy? I'm hoping I can go straight to 3.5" - I have the setup disk on a 3.5" disk, but my 5.25" drives keep failing before I can make a 5.25" disk.

    It's a really neat machine, and except for a couple minor issues, in good shape. My wife thinks I'm crazy.

  8. #8
    Join Date
    Dec 2005
    Toronto ON Canada


    Quote Originally Posted by idunno View Post
    I just recently got a Compaq Portable III, and I have to admit, finding posts like this was why I bought it. ...
    It's a really neat machine, and except for a couple minor issues, in good shape. My wife thinks I'm crazy.
    Congratulations! Your wife is right of course, but crazy people are generally happier and have more fun than the rest.

    Since you seem to be new here, it might be useful down the road if you put your location in your profile, please?

    Good luck!

  9. #9


    With a 1.44MB drive and default settings, it won't boot off a 1.44MB formatted disk but you might be able to get it to boot a 3.5" that has been formatted to 360KB and change the setup that way.
    Last edited by Wormetti; November 10th, 2013 at 08:20 PM.

  10. #10
    Join Date
    Nov 2013
    Netherlands, Near Amsterdam


    Very nice, fantastic machine! I had one a few years ago.


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