Released October 6, 1988, MS-DOS 4.0 is the forgotten DOS. As such, modern hobbyists are often curious about it. Why did so few people use it?
It was eagerly anticipated and was years in the making, so it’s fair to say DOS 4 was a letdown. It’s a misnomer to say no one shipped PCs with it and no one used it, just like it’s a misnomer to say no one used Windows Vista. But it’s very apt to compare DOS 4.0 with Windows Vista and there were very valid reasons to avoid it in the 1988-90 timeframe. It’s also fair to be curious about it.
Problems with MS-DOS 4.0 and even MS-DOS 4.01
There was no shortage of rumors regarding MS-DOS 4.0. I was into computers at the time, but I was a Commodore 64 and Amiga guy. That said, I knew from reading the general computer magazines that covered multiple platforms that DOS 4.0 was problematic. I didn’t have specifics, but I knew it was buggy.
Specific information was a bit difficult to come by, which I find odd because when MS-DOS 6.0 came out and had issues with its disk compression, I knew specifics. It might be because there were approximately twice as many PC owners in 1992 as there were in 1988. I’m not sure.
But for whatever reason, I knew that DOS 6.0 was fine as long as you didn’t run Doublespace disk compression, but I didn’t know if there were any mitigating factors about DOS 4.0.
Today, a great deal of that late 1980s content is available online and searchable, so with enough digging, it is possible to find out what was wrong with it. I found two specifics in two different magazines.
Buggy file caching
The Nov 29, 1988 issue of PC Magazine reported IBM PC DOS 4.0 was buggy, so Microsoft waited, and IBM shipped a fixed version without changing the version numbers. Further research showed DOS 4 had the ability to move buffers and other items related to file caching from conventional memory to expanded memory to free more memory below 640K. But this was initially buggy.
Corruption with large disk partitions
The April 17, 1989 issue of Computerworld reported a data loss issue with disk partitions larger than 32mb, requiring another fix.
So basically all the reasons people were interested in DOS 4 was buggy.
Based on that last article and its late date, if I were going to run DOS 4.0, I would hesitate to run any version of MS-DOS 4 other than Compaq MS-DOS 4.01D.
The open-source MS-DOS 4.0 fixed most of these bugs, but I’m not 100% certain it has the bug fixes in those final Compaq builds.
Did any PCs actually ship with MS-DOS 4.0?
Looking around online, you can find people claiming that OEMs didn’t even bother shipping PCs with MS-DOS 4.0. That is an exaggeration. Looking at Winworld, you can see OEM versions of DOS 4.0 from several big name PC brands. OEM builds from Compaq and Packard Bell wouldn’t exist if they hadn’t shipped them.
The situation with bundling the operating system was a little bit different in 1988 and 1989 than it is today. Flipping through a computer magazine of that era, you can find PCs bundled with DOS 3.2, 3.3, and 4.0 in the same issue. Some vendors offered you a choice.
Northgate was an example of a PC maker that offered a choice. The other thing I found interesting was that Northgate charged $20 extra for DOS 4.0. it is not entirely out of the question that some customers may have opted for DOS 3.3 just to save a little money.
Other objections to MS-DOS 4.0
The other major objection to DOS 4.0 was the amount of disk space it used. DOS 3.2 or 3.3 installed in less than a megabyte.
One of the key selling points of MS-DOS 4.0 was that you were no longer limited to 32 MB disk partitions. So if you had a 40 MB hard drive, you could partition your C drive as 40 MB, instead of having to split it into 20/20 or 32/8.
The problem was, you gave back 3 MB of that bigger C drive to run DOS 4.0, unless you were knowledgeable enough to go in and remove the parts of it you weren’t using to save space. That is definitely not something everyone was comfortable doing.
What people did instead of running MS-DOS 4.0 or 4.01
So what did you do if you wanted the benefits of DOS 4.0 but didn’t want to deal with the bugs? Someone who was really knowledgeable about PCs in the late 1980s had options, and they knew they had options.
Use a third-party DOS shell
First of all, the major benefit of DOS version 4 was that it came bundled with DOS Shell. The thing was, there were third party programs with equivalent or better functionality available even before DOS 4.0 came out. Examples included XTree Gold and Norton Commander. I knew some DOS power users who continued to use those two programs clear up until 1995, when Microsoft released Windows 95.
Use a third-party command interpreter
The other major benefit was DOSkey, a utility that provided command line history. That way, if you typed a long or difficult to remember command, you could arrow up and down through your history the same way you can on a modern command line today. That was a really big benefit. But a third party command interpreter called 4DOS was released in 1989 that provided command line history, tab completion, and even more than DOSkey provided.
Overcoming the 32MB partition limit
Even the partition limit was possible to overcome with a third party disk overlay, such as one sold by Ontrack. Or if they could get their hands on MS-DOS 3.31, they would get that same benefit.
DR DOS
An underrated option was to switch entirely and adopt DR DOS. DR DOS wasn’t quite 100% compatible with MS-DOS, but depending on what you were doing, it was sometimes close enough, and it had better utilities than Microsoft provided. Maybe DR DOS wasn’t popular enough to consider it mainstream, but it had a devoted following. It was the Jane’s Addiction of DOS, while MS-DOS was as mainstream as Michael Bolton.
Power users loved their third-party utilities
There used to be a whole industry around utilities that extended the functionality of DOS. MS DOS 5.0 and 6.0 wiped out an awful lot of that industry, which was good and bad. It was good for the average consumer because they didn’t have to go and buy $200 worth of additional utilities to perform basic tasks. But it sent those software publishers who developed those utilities scrambling to come up with products so they could stay in business, and the built-in utilities were rarely as good as the third party utilities.
But in 1988 and 1989, it was entirely possible to build your own DOS 4.0 like experience without the bugs.
I know part of the appeal of DOS 4.0 is the perception that it’s what power users would have run at that time.
But my experience was at the time, a DOS power user was more likely to run DOS 3.3 with their preferred selection of third party utilities to enhance it.
Some people did use it, it was just a minority
So that’s not to say nobody used MS-DOS 4.0. At the very least, the people who wrote books about MS-DOS 4.0 used it while they were writing their books. And it worked well enough that they were able to finish their manuscripts, which was no small task. Either they were using DOS 4.0 on a daily basis for between 6 and 12 months, or they had a PC running DOS 4.0 that they tried things out on, and another PC sitting next to it they used for writing.
There is nothing wrong with trying it out to see what it was all about. But there was also good reason DOS version 5 caught on and version 4 didn’t. DOS 5 really learned from the mistakes of DOS 4.
For these reasons, I don’t have any version of DOS 4 on my list of recommended operating systems for vintage PCs.
David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.