tkc8800

Technology and retro computer blog

Compaq Portable

I saw this Compaq portable advertised in my local area, not knowing much about these machines I did a bit of research on it. I discovered that it was not only the first IBM pc clone but also Compaq's first product from the early 80's. I really like these old "portables" with built in CRT's so I snapped it up. The price was fairly cheap, so I bought it without doing much testing. The seller didn't have any working boot disks, so I just tested that it powered up and displayed a missing boot disk prompt on the screen, that was good enough for what I paid.

 

Compaq Portable Compaq Portable Inside Compaq Portable Inside

 

Compaq Portable specifications
Manufacturer Compaq
Release date January 1983
CPU Intel 8088
Speed 4.77MHz
Ram 128k to 640k
Rom
Storage internal 5.25" 360k floppy x 2
Expansion 3 slots
Ports Serial, parallel, composite video out
OS Compaq/MS DOS

 

Compaq Dos

Compaq_dos_2.12_5.25.zip (177.65 kb)

compaq_dos_3.31_3.5.zip (1.05 mb)

 

On getting it home and doing some initial testing, I was happy to get it to boot from the A drive with a DOS 3.3 boot disk, but on the down side, I couldn't get any of the keys on the keyboard to respond. No really being able to do much more at that stage I pulled it apart and and gave it a full clean out. On pulling apart the keyboard I discovered that is uses sponge foam as a spring inside the keys.  I've never seen these before, but in doing a bit of reading I found out they are used on several other models like the Sol20 and Apple Lisa.  It was pretty clear to see why none of the keys were working as both the sponge material and the Mylar on the key pads had totally perished (see photo below).

 

I read a great guide on the Solviant website about replacing keys on the Sol 20.  The guide suggested making your own pads using sponge discs topped with aluminum foil and clear plastic tape. I didn't have any sponge material on hand so I just used some padded double sided tape instead. I create a test key and tested it on the keyboard pcb and all keys worked. I then proceeded to make similar pads for all keys on the keyboard. This took a couple of hours but once re-assembled, I had a fully working keyboard. The keyboard fix was good as I can now use the machine, but I'm not happy with the feel of the keys. The double sided tape that I used does have some spring to it, but it's way too hard compared to the sponge material. So at some stage I'll redo the pads using a more appropriate material.

With a working keyboard I did some further testing on the machine and found that the B drive didn't read any disks. I pulled it out and cleaned it internally and also did a thorough head clean, on re-installing the B drive it now reads some disks, but it's not perfect. I've noticed it gets to a certain track on the disk and then comes up with read errors. I'll need to extract that drive again and check the rails for debris. I can launch some programs from that drive now so it's better than before. Everything else on the machine seems to work well, the display is good, there's some geometry issues, but the green screen display is very sharp and there's no sign of any burn in. The machine has the floppy controller/printer card, an AST SixPakPlus clock/memory/serial upgrade card installed.  Memory reports at 640k, I also replaced the 3v battery on the AST card and I found the AST clock utilities on web, the clock now saves the date and time.




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