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Compaq MS-DOS 3.31

MikeS

Veteran Member
Joined
Dec 23, 2005
Messages
7,506
Location
Toronto ON Canada
I think I've got a copy on 5 1/4" and maybe even the manual, but no guarantee and it'd take a while to find, but if you don't find one elsewhere I'll look around.
 

Raven

Veteran Member
Joined
Mar 7, 2009
Messages
2,752
Location
DE, USA..
What makes Compaq's 3.31 so unique is it supports FAT16 prior to the mainstream DOS doing so, which was in MS-DOS 4. The groundwork for it (16-bit addressing for hdds) was in 3.30, which is how Compaq managed to add it w/o breaking compatibility.

I figured most of you wouldn't know this, so I'd throw it out there.
 

cgrape2

Experienced Member
Joined
Jun 11, 2009
Messages
285
Location
Lodi,CA
I'm fairly sure I have a set of the images around here somewhere.I'll look if you'd like.
cgrape2
 

FishFinger

Experienced Member
Joined
Sep 19, 2009
Messages
299
Location
UK
I've got it on 3.5" (it came with my Compaq Portable 386) and can make images if you like.
 

mycall

New Member
Joined
Oct 8, 2008
Messages
6
DOS 3.30 is common, not DOS 3.31. I would love an image copy if you have one.
 

BlueofRainbow

Experienced Member
Joined
May 30, 2006
Messages
55
Just curious.

Has anybody attempted to document what are the differences between both versions (3.30 vs. 3.31) from Compaq? There may be some historic interest in knowing what Compaq did to support hard-drive greater than 32 Mb without breaking the rest of DOS.
 

Captain Midnight

Experienced Member
Joined
Mar 3, 2010
Messages
52
I don't know about all the background coding they did, but if I remember right, it was Compaq's code base that was, in part, integrated into DOS 4.X and future versions. That in itself isn't too surprising because during the late 80s, Compaq and Microsoft had a major joint venture going on around the Deskpro 386 (not to mention CEMM, Windows/386, etc.).

In any case, I do know that in Compaq DOS 3.31, Compaq bundled a device driver called ENHDISK.SYS, which basically allowed 3.31 to read/write/format/etc. to partitions formatted under prior DOS versions.
 

vwestlife

Veteran Member
Joined
May 2, 2008
Messages
5,194
Location
central NJ
What makes Compaq's 3.31 so unique is it supports FAT16 prior to the mainstream DOS doing so, which was in MS-DOS 4. The groundwork for it (16-bit addressing for hdds) was in 3.30, which is how Compaq managed to add it w/o breaking compatibility.

I figured most of you wouldn't know this, so I'd throw it out there.
Regular DOS from IBM and Microsoft was already using FAT16 as of version 3.0. They just didn't enable support for partitions larger than 32 MB until DOS 4.0, while Compaq did it earlier. I just formatted a 32 MB partition on my XT clone using genuine IBM PC DOS 3.30 and it is a FAT16 partition. Same thing when using the Packard Bell and Tandy OEM versions of MS-DOS 3.30.
 

Captain Midnight

Experienced Member
Joined
Mar 3, 2010
Messages
52
Regular DOS from IBM and Microsoft was already using FAT16 as of version 3.0. They just didn't enable support for partitions larger than 32 MB until DOS 4.0, while Compaq did it earlier. I just formatted a 32 MB partition on my XT clone using genuine IBM PC DOS 3.30 and it is a FAT16 partition. Same thing when using the Packard Bell and Tandy OEM versions of MS-DOS 3.30.

And for Compaq, the major thrust behind that was the Deskpro 386, Portable III and Portable 386, because except for the base model of the Portable III, all those computer came standard with a drive greater than 32 MB.

Besides all that, this was an OS that could fit on one HD 3 1/2" floppy, read big drives, could format the HD 3 1/2 floppy just fine and loaded in about 40K of memory. What more could you ask for? Ok, so it couldn't load high, even with the assistance of DOS-Up with QEMM/QRAM (COMMAND.COM can, but not the two main system files). But then again, I've got this setup running on a Compaq Portable 386 with QEMM, and all told, I've got the mouse driver, a disk cache, After Dark for DOS and packet drivers loading, and I still have 590K of conventional memory left. And to top it all off, it boots to DESQView, so I can multitask DOS apps. Very nice.
 

BlueofRainbow

Experienced Member
Joined
May 30, 2006
Messages
55
Interesting about ENHDISK.SYS and it's use was apparently not limited to Compaq DOS 3.31 from the followng (from http://support.microsoft.com/kb/80890):

"Compaq technical support has confirmed that extended drives created with FDISK.EXE and ENHDISK.SYS under Compaq's original equipment manufacturer (OEM) version of MS-DOS 3.2 or earlier may be inaccessible after upgrading to MS-DOS 5.0 or later.

The ENHDISK.SYS device driver made it possible to access multiple MS-DOS partitions created by earlier versions of the MS-DOS FDISK utility on fixed disk drives. ENHDISK.SYS was used under Compaq MS-DOS 3.2 and earlier to provide partitioning support for hard disks greater than 32 MB.

ENHDISK.SYS had to be the first device driver installed in the CONFIG.SYS file. This was done to ensure consistency for drive assignments through all the utilities that support partitioned drives created by earlier versions of the FDISK utility. "

From this, it seems that ENHDISK.SYS was to access multiple partitions on a >32 Mb hard drive.....not a single partition >32 Mb. A slightly different purpose?
 

Robin4

Experienced Member
Joined
Sep 25, 2011
Messages
378
Someone that could send me all the images of the orginal floppys of compaq MS-dos 3.31..??

Iam trying to find the orginals, but that seems really hard to get those..

Iam allready have images of floppy, but those seemed not all the good ones..

If someone could help , that iam really grateful.
 
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