Why is DOS 4 considered terrible?

Comments here and about amount to ‘sure they only release the source for the terrible versions of DOS.’ or ‘Wake me up when it’s 6.22.’

IIRC the source also includes the attempts at multi-tasking and by my reckoning isn’t this going to be helpful to projects like freeDOS, DOSbox and the like regardless? Or even just someone wanting to make patch files because there are people that insane out there.

Personally I’m waiting on them releasing Windows 95’s source. that… theoretically could happen before I’m dead if I live long enough.

I consider all DOS horrid for the lack full IRQ support, mostly on the serial ports.
The brain dead 286 did nothing, to give linear memory addressing. By the time
the 386 came out, microsoft was pushing windows thus one never seemed have a
a real DOS and no 16 bit segments.


I was never really a user of DOS, but from a history perspective, I’m interested in questions like “what was new in DOS 4” and “what came in the next version which made it better.” In that light, there’s an interesting article here with plenty of detail:

DOS 4.0 (OS/2 Museum)

DOS 4.0 was relatively poorly received. Some of the criticism leveled against DOS 4.0 was justified, and some of it wasn’t; however, it stuck and DOS 4.0 never managed to shake the bad name.

Among the more widespread problems with DOS 4.0 was incompatibility with leading disk utilities. This was natural and inevitable. Since DOS 4.0 supported large disks with 32-bit sector addressing, the disk format had to be different


The poor reception of DOS 4.0, together with the relative lack of attention given to DOS by Microsoft and IBM, created an opening for Microsoft’s long-time competitor, Digital Research. DR DOS 3.x gained favor with some OEMs by virtue of being significantly cheaper than MS-DOS. However, by 1990 Digital Research offered DR DOS 5.0 (since DOS 4.0 had a bad name, DR went from 3.41 straight to 5.0) which was widely accepted to be superior to MS-DOS 3 and 4.

This caused some serious anxiety among high-ranking Microsoft officials. DOS was Microsoft’s cash cow, which funded expansion into other markets. If DOS income were to be severely reduced, it would have caused big financial headaches for Microsoft.

Microsoft naturally realized that and scrambled to release DOS 5.0, “accidentally” matching DR DOS feature for feature. The release of DOS 5.0 in 1991 spelled a quick death for the unpopular DOS version 4.0.


As I recall windows had a few hidden calls so that it wouldn’t work right or possibly at all under DR DOS.

So even without the multi-tasking components (I think the source has the attempts made to give DOS multi-tasking,) it does seem to be signifigant in giving a competetor a foothold that Microsoft responded to in… the microsoft manner.

There was a great deal of controversy about Windows and DR-DOS.

People did find code in Windows that basically said “Oh, I’m not running on Microsoft DOS - then I’m not going to run.”

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May I ask what you were using instead of DOS at the time?

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Sure! My contribution in the Introduce Yourself thread tells a bit of the story:

I used Amiga (500, then 1200) until my switch to PC, which came in the Pentium era when Linux was possible, so my first PC was configured as a dual-boot into Slackware, the other side being, I think, Windows For Workgroups but very rarely used.

My exposure to DOS was all vicarious - mainly the pages of BYTE, Chaos Manor and the like. I’d read a lot about CONFIG.SYS but not touched a file of that name!