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What's the most recent MS-DOS that's compatible with the Compaq Portable 1?

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dag10

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Jul 30, 2011
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I have a Compaq Portable I from 1982. Apparently, they originally shipped with MS-DOS 1.1.

Does anyone know what is the most recent version of MS-DOS that would still be compatible with the machine? It has no Hard Drives, only two 5.25" floppy drives.
 
Well, in theory, you can run any version of DOS right up to 6.22 on a floppy-only system. But the size of a 6.22 system compared to a 360K-drive box will impose severe limitations on what you can do.

I'd either get a hard drive card, such as our own XTIDE, or stick with MS-DOS no later than 3.3.
 
You might have more luck searching for it as XT-IDE, or just try searching the forums here. I know that bare boards are still available, but it'll probably be a while before anyone's ready to send some out in kit form again...
 
If I could get a bare XT-IDE board that's already etched and drilled, then I'd be able to gather the components and assemble it myself. I have the equipment for soldering components, but I don't a drill.

EDIT: I also have an Arduino Uno, which will allow me to burn the EEPROM.
 
Wait, though. Would the XT-IDE controller definitely work with the Compaq Portable? I'm still rather new to vintage computers. :p
 
Chuck(G) said:
or stick with MS-DOS no later than 3.3.
Click to expand...
Good advice right there - It's why I stick with DOS 2.11 on my Tandy 1000's. Nothing like having a fully working DOS up and running on a 640k machine, and having 612k reported as free memory after startup with joystick.sys and zansi.sys loaded.
 
Also hard disk performance can be better using FAT-12 with many less buffers allocated, as the FAT is so much smaller (and hence it's more likley that required FAT reads will be serviced from the DOS buffer pool).
 
I know I ran DOS 5 on 4.77 MHz 8088s, and I may have even run DOS 6 on them, but didn't really see any benefit. 386s and up can benefit from DOS 5 and 6, and arguably 286s can benefit in some cases. But since 8088s don't have upper memory or high memory, all they really get is bloat. So I'd stick with DOS 3.3 or older and add a third-party text editor and whatever other utilities you need.

One thing you can do to ease the pain of only having two 360K drives to work with is to run UPX on the .com/.exe files to pack them down some. UPX has a --8086 switch to keep it compatible with older PCs. I would suggest running UPX from a modern machine though; it'll take a lot less time. You can find UPX at upx.sourceforge.net.
 
I agree and disagree with the DOS 3.3 or earlier recommendation. For most applications you are right..... DOS 3.2 or so is probably the best. BUT if you are using the machine with INTERLNK and want it to play nice with machines that have later versions, it won't work so well.

I ran into some problems when I INTERLNK'd my 5140 running 3.2 to my junkbox server which was running 5.0. The solution was easy though.... just boot the 5140 with 5.0.

OTHER than that scenerio.... I'd stick with ~DOS 3.2.
 
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