Restoring a 1987 Compaq Portable II

Someone years ago gave me a Compaq Portable II. I always have loved this machine. Coming from the days of “luggable” computers, it weights over 20 lbs, and has a tiny CRT. The model I have has a “Type 2” (20MB) hard drive, and 640KB of RAM. For a little bit I thought my parents had accidentally thrown it away, as I was storing it at their house. Then it was found again and much rejoicing was had. The system is a Intel 286, with no math co processor.


Recently the one I have has come down with a few problems, so after seeing a brave young soul take their apart ( I decided I should give it a go. First the battery on the motherboard started to fail, not only resetting the clock when it lost power, but also forgetting the type of hard drive it had. This made it so every time the system was used, you would boot a 5 1/4″ floppy of MS-DOS, then change floppies to the Compaq Diagnostic disk, and configure the BIOS, and finally go back to the MS-DOS disk. I was lucky that some places still have the disc images online; . I attached those disks to the bottom of this page just so there is another mirror online for others.

I knew that the BIOS battery needed replacement, but when I recently turned the system on the old hard drive had finally given up. At about 30 years old I can not blame it. A fun fact about the drive in this system, it is actually a MiniScribe MFM hard drive (more info here that has a MFM->IDE conversion board on it. The drive is also shock mounted, this computer is portable after all! Knowing that, I decided it was time to swap that dead drive for a Compact Flash -> IDE adapter. This would be a size and speed improvement over this old hdd. Luckily someone else had already attempted this!

Armed with all that info (and the manual – I took the system apart, and very carefully avoided the high voltage CRT area. After getting the top cover off, then the front bezel; I needed to remove was the floppy and hdd caddy. I removed the cover of the caddy as well as the rear card cover. Then I could get access to the ISA cards. This system has the standard IDE control board, the video board, then a blank, and finally a board called EVEREX with a crazy connector. I have no idea what that last board ever went to. Some quick googling says it may be a tape controller card, or an special external monitor. My plan was to use the third slot to put the Compact Flash adapter, that way I can access it externally. (Here is it being tested)


I got a 8gb card off Amazon because it was fairly inexpensive and that would be so much more than plenty. After looking through all the options the system gave me, I settled on a “Type 41” hard drive even though the system auto detected it as a “Type 14” This gave me around 250MB of storage, for my uses that was plenty.

Now to replace the BIOS battery. The manual covered this. The battery is under the cover, where the extra RAM would be, IF I HAD IT. I took the bottom off, cut the zip tie that held the battery, and replaced it with one off Amazon. That first battery lasted about 25 years before it finally stopped remembering, I think that is a good battery.

One thing that stood out was the battery. I got a battery from the same company as the original, photo above; the battery on the left is the new one, the one on the right is the 30 year old battery. These batteries are 30 years apart, yet they look almost identical. I think that’s hilarious and interesting.

It came time to close up the case, mostly replacing metal covers around the system then placing the cover over it all. I ran into a little problem replacing the ISA card cover, there are little feet that hold the cards in place, but my IDE cable and power cable were in the way. I had to push the cables closer to the ends of the cards to make the cover fit. Then I used plastic twist ties to hold the power cable in place.

Right before sealing it up again, I cleaned the cases because it was already off. Below are some photos of the final system. The next thing I would need to do is replace the keyboard cable, the plastic is chipping off. I did a quick glance at how hard that repair would be, the issue is the cable goes into the monitor compartment (high voltage capacitors are scary) and I will need to solder a new cable to the keyboard/cable which is more than I was looking to do in this first repair session. I also one day should get a ISA RAM expansion card. A giant benefit to having the Compact Flash card slot on the side, is if I want to load more software I can just take the card out and plug it into a modern PC. I also can create a VM and use that card as the hard drive, making for easy dsk file image installation. This is close to infinite times faster than serial connections to transfer files.

This system has a Intel 286 with 640KB of RAM. To run Windows 3.1, you need extended memory; which I currently do not have. If I had a 386, then I could create a page file, and use disk space as memory, but a 286 does not have this ability. To have some version of Windows I installed Windows 3.00a off of, they have a great collection of Windows versions, with different languages and builds. I have a ton of old Windows versions in packaging, but this was simply easier. I also got a MS-DOS 6.22 bootable installation image off of and installed that as my base.

All in all, this PC got some much needed attention and is now back to its old self. The Compaq Portable II is back to its old brilliance with Windows 3.0 on its 250MB SDD (technically it is a SSD), 5 1/4″ drive, and tons of games, as it should be.

Random bonus: I enjoy the Compaq Setup Disk load screen, it has a animation with the logo that uses the slow refresh time for an interesting effect. Below is a Imgur upload of it.

Files (recently moved over to from Google Drive):


  1. Just wanted to say thank you for posting this and sharing the info you found, it was most helpful!
    I just restored my own unit, and this was a tremendous help.

    Keep up the great work!

  2. Hello , how to write .dsk files to 3.5″ 720K floppy disk ?
    I have compaq portable II and I need to install HDD.
    On the boot screen it ask me about Compaq User Diagnostic disk.

    1. I think I used Linux to dd it to a 3.5” floppy, also I have a compact flash adapter and could just copy the image to one of those disks. :/ I don’t have a direct solution, do you have another machine you could use?

      1. yes I’ve many anotler machine with 3.5″ & 5.25″ . Just I don’t understand how to burn .dsk image files to floppy disk. Because no any image burning software support it. I try too many image burning software. But result failed.

  3. Thanks for all the helpful info.

    I just found a portable ii at a garage sale and I’m trying to write those disk images to floppy. Can you tell me what program you used? Both DiskWrite and WinImage tell me that they are invalid.

    1. I’m the past I would mount the floppy image in virtual box and take the files off I need. I also had another machine with 3.5”->5.25”, so I could chain modern system, to that box, to compaq.

  4. Do you have the details of the battery (volts mAh etc)? Or details of where you purchased it from? I could not find any useful information from the service manual. Thanks in advance!

  5. I own a Compaq Portable II and intend on replacing the mechanical drive with a CF (or SD) card at some point, although in my case its original 30 MB drive is remarkably still working, so I’ve been in no hurry. I was curious about what drive type to use in the BIOS of my machine when using a CF card, and found your blog entry.

    You say the BIOS autodetected your CF card as Type 14, however I suspect this was simply the BIOS remembering the drive type of the mechanical drive that was installed prior. I don’t believe the Portable II BIOS is capable of autodetecting drive types, as this feature wasn’t common in BIOSes until the 386 or 486 era.

    I’m curious why you chose Type 41 (250 MB) instead of Type 42 (500 MB). Was it a case of Type 42 not working with your CF card?


    1. I ended up changing the type to the biggest one the bios disk let me, then that worked fine. No matter what, the smallest CF card I could find was a few GB and the biggest setting the bios had was a few hundred MB; thus the biggest worked fine for me. 🙂

  6. “I don’t understand how to burn .dsk image files to floppy disk.” The .dsk Images were created with CopyQM (Sydex product) and needs to be written by DOS to A: on a DOS Computer with
    copyqm A: playback=mysaved.dsk
    (There MUST be a file named C:\DISKETTE.CFG that contains the Floppy Drive info like other
    Sydex Products.)
    With the floppy created just insert it in your Compaq and it should boot properly.

  7. I hope you’re still around to help me out a bit:)
    None of the links are valid anymore(and the one that’s valid doesn’t have correct links to the downloads anymore), but then again this article is 3 years old so I can’t blame you for that.
    Anyways, I’ve been trying to get my Portable II to boot from a CF card(which is loaded with the programs on the original setup disk) but I keep getting the no-setup-disk error. I am sure everything is wired up correctly. What am I doing wrong? Thanks in advance!

    1. Hello,
      Still here, I am not having issues with any of the links, which ones are giving you problems? Have you booted the system via a floppy first to setup the CF card? Since the BIOS stores which type of hard drive you ahve and the odds that your BIOS battery is dead are high, you may need to boot the floppy setup disk first, then the CF card should work. Also you need to format the card in the device since the older not full IDE can be wonky. Let me know!

      1. I am currently trying to get someone to make a floppy for me as I don’t have the stuff to do it myself. The link for the tkc8800 isn’t working, and I know you can’t do anything about this one, but none of the download links in the yesterbits you linked to in your article is working. If you still happen to have the 360k disk image for the diagnostics and dos disks, could you please email me or post it somewhere? Thanks a lot!

      2. At the bottom of the article, under Files: I have copies of a lot of the disk images there 🙂 I dont actually have the Portable on me now its in storage that I cant easily get or I would send you disks. I think you are in luck though! People over at this post are currently working on a Portable I and people have volunteered to make disks. Want to give that a shot and if you dont find any luck in the next month or two I could make some.

  8. I am currently trying to get someone to make a floppy for me as I don’t have the stuff to do it myself. The link for the tkc8800 isn’t working, and I know you can’t do anything about this one, but none of the download links in the yesterbits you linked to in your article is working. If you still happen to have the 360k disk image for the diagnostics and dos disks, could you please email me or post it somewhere? Thanks a lot!

    1. It’s been a long while since the last post, but… someone from Greece is selling Boot, DOS and Diagnostic disks for all (or each?) Compaq Portable, for $26 on eBay, and several weeks waiting time to North America. I can’t vouch for him, yet, but the big problem is there are no USB 5.5″ drives, AFAIK. Therefore, you have to find an old enough working PC to have a 5.25″ drive, and another means to transfer the images, either an internet connection to or perhaps, and some combination of wired or wireless network, Laplink through parallel port, Firewire?, USB, hard drive, zip drive, or 3.5 drive, to transfer to 5.25″ disk.(which are also tricky to get hold of) Unless you work with older PC tech for a living, it’s likely to be either more than $26 and/or hours of labor to achieve. Good Luck everyone!

      1. Another option is to get one of the IDE to compact flash/SD adapters and setup the disk on a modern pc. 🙂 It does take a lot of back and forth to get it right though

  9. Thanks for posting, I wish I had the time to fix and document my old computers as you did.

    Maybe you already know, but early Compaq machines did not have a regular CGA board but a so-called Compaq VDU (Video Display Unit). Which is a CGA with high quality text mode AND a double-CGA mode (640×400), very convenient for Windows.

    As far as I remember, his mode was available from Portable 1 to the pre-VGA Deskpro 386 mono (color was EGA).

    1. I didn’t know! I haven’t had as much time recently… but I do have a IBM 5150 replica board in the works! I swear I had Windows 3.1 in the past working on this machine, burning think it’s memory board is acting up. I eventually need to figure out how to replace the keyboard cable, the plastic on it is crumbling.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s