Tjyylli

Why did Microsoft make DOSKEY a separate command, instead of integrating it with COMMAND.COM?

I don't think DOSKEY uses a lot of RAM or was useless in the '80s... Maybe there was another reason not to enable this command automatically?

I can think of a number of reasons:

• 
  DOSKEY isn’t specifically tied to COMMAND.COM; it provides history for any program which uses the same input functions as COMMAND.COM, and one could imagine wanting to run DOSKEY with another command interpreter (although the most popular alternative command interpreter, 4DOS, already included equivalent features);


• 
  DOSKEY was introduced late in MS-DOS’s life, in version 5 (1991); since it changed input handling (with its macro support in particular), the MS-DOS developers might have thought that some users wouldn’t want it, or that it could break things (backward compatibility was already very important for Microsoft by that time);


• memory really was tight in DOS, even with the support for UMBs introduced in DOS 5.

The first reason is really sufficient from my point of view: input editing isn’t handled in COMMAND.COM, so improving it in COMMAND.COM wouldn’t have made much sense.

It turns out DOSKEY’s developers forgot one important feature of the DOS input routine (it’s supposed to handle the date change at midnight), so making it optional turned out to have been a good idea!

(There were a number of history-providing TSRs already available then, but that wouldn’t have been a consideration for Microsoft.)

Well, first of all, isn't it best if an OS is configurable for each user the way he needs, instead of packing everything into one bloated package?

• Basic DOS is supposed to run on small machines, thus a small footprint is a major reason. Making everything non essential (and user convenience is) optional helps


• Not every User might like or even need it


• There might be scenarios where DOSKEY is harmful


• DOSKEY is - like many other 'comforting' add-ons - a late comer.


• Did I already mention RAM size? Even with full 640 KiB (and UMB), DOS memory was quite challenged when DOSKEY became available.


• Even if it's 'just' a few KiB, it could really be a drain.

Long story short, having a configurable system to be tailored to each job needed is quite an advantage worth paying the price of a few bytes wasted for headers and duplicate code plus a few milliseconds during boot.

The early architecture of COMMAND.COM (based on detailed analysis of DOS 2.1 a long, long time ago) was that a program requesting maximum memory could overwrite all of COMMAND.COM except a tiny portion which would reload from disk on termination.

By the time DOS 5 was released, 1MB RAM was not uncommon, so this motivation had gone.

But Windows 3.0 was released before DOS 5 and Microsoft started pushing for everyone to run Windows all the time, rather than just loading Windows 2.1 runtime for Excel or Pagemaker.

Windows 3.0 loaded on top of DOS, and it was common to open a DOS box or run batch files within it. Any bloat in COMMAND.COM would be loaded multiple times.

So I suggest that integrating functionality to COMMAND.COM would have been an unwise architectural choice in those days.

When MS-DOS 5.0 launched, Microsoft made the new features of DOSKEY a selling point of the new O/S, one of several improvements which made it seem worthwhile to buy the new version rather than stick with MS-DOS 3, which many users (me!) were still running.

MS-DOS 4 had not been exactly a blazing success (in terms of persuading consumers to part with their cash). I don't seem to be able to recall it having any particular benefits, over and above MS-DOS 3 (hence I went direct from MS-DOS 3 to 5), whereas the competition from new versions of PC-DOS and DR-DOS was pretty hot.

Microsoft were as much about making change for the sake of it, just to seem to be doing something, with MS-DOS 4—whilst also battling with the competition on the GUI platform, with Windows 3.1 getting launched about that same time.

All the software companies were desperate to show beleaguered users that command-line operating systems could be easy to use, given that users could not jump onto a GUI easily (Windows 2 was a real clunker, and no one other than Microsoft was seriously trying to develop a PC-based graphical user O/S).