GreyCloud said:
In my experiences with MS-DOS, I've never seen 4dos.exe. The only thing
that I saw was command.com... msdos.sys & io.sys.
The bios usually has to do with low-level system calls. I used to have
the IBM reference books on those system calls, but never saw things like
CD, COPY, REN, etc. in their book.
I suppose I could fire up the old IBM I do have and try this myself.
4DOS
Caldera OpenDOS
aka Novell DOS (after Novell acquired Digital Research)
aka DR-DOS (DR = Digital Research)
FreeDOS
aka PD-DOS
Those are the ones that I remember. There were a slew of "hobbyist" DOS
shell alternatives but those projects were too tiny to have any impact
regarding usage of alternative or replacement command interpreters.
Whether or not you even know the DOS shell can be replaced really
depends on how long you have been using PCs. Many were introduced as
enhanced alternatives to MS/PC-DOS (i.e., richer and more powerful
commands and features) or as a consequence of Microsoft's announcement
that it would no longer sell MS-DOS (c.1994?).
Anyone that bothered to learn MS-DOS would find out how to edit the
config.sys file and what all of its settings meant. That meant you
would have learned about the 'shell' and what it was for. However, the
vast majority of users never bothered to crack open the config files or
even look at the options in their apps. They weren't interested in
knowing the OS and often understood or used just a fraction of the apps
they installed. Using computers wasn't fun for them. It was a chore.
It's similar to the difference in users of cars: some like to work on
their own cars to fix or enhance them while others just want to use them
and pay someone else to repair them.
