Filetypes (was Re: Xerox)

From: D. Peschel <dpeschel_at_u.washington.edu>
Date: Wed Dec 16 18:25:24 1998

> That was one thing that seriously irked me about Apple DOS 3.3 was the
> differentiation between Applesoft, Integer BASIC and binary files. I could
> understand text files being a separate file type, but *binaries*?

Yes, I suppose that's rather quaint... modern systems hae solved that
problem -- by not having BASIC built in, which is not necessarily a
solution. On the other hand, it is true that the two file types are
supposed to work differently. Would you want to load a machine-language
file and have BASIC interpret it as tokens? The result would be a disaster.

You could use a UNIX-like approach and have one file type (binary) or maybe
two (binary and text) and leave it up to the user and programmer to choose
the right commands. I'm not sure that fits in with the "easy-to-program"
mentality of the Apple, though. Besides, BASIC had already been created
when DOS was designed.

This brings up another point -- given that you have multiple file types,
wouldn't it be safe to have one command that acts differently on all of
them? (This is the reverse of the UNIX-like apporach.) It's a pain that
DOS made you use separate commands for all of the filetypes. Someone
published a chunk of code that added a - command like ProDOS', and some
other goodies. (I think the code was published by the A.P.P.L.E. user
group, which BTW was a local and very productive group.)

Actually, some of the types aren't really accessible at all! (There are no
useful commands for displaying text files, for example. Though EXEC is nice
and not used often enough.) Did you know that there are EIGHT file types in
DOS? They are:

        T text
        I Integer BASIC
        A Applesoft BASIC
        B binary (absolute)
        S system -- not used by anything except simple protection
                schemes
        R relocatable binary -- requires a relocating loader (usually
                called RBOOT or RLOAD, I think). The relationship between
                the loader and the OS is very weak; I don't know if the
                loader checks the types of files it loads, and I doubt that
                the OS knows about the loader at all.
        A Another type A -- not used by anything
        B Another type B -- not used by anything

If you look through memory, you can find the string BARSBAIT.

> The Commodore's filetypes are silly. PRG, SEQ and USR are all just sequential.
> Only REL is truly different.

That is kind of silly. I assume you couldn't do anything with USR files?
Again, I object to the lack of available actions more than the artificial
distinction of file types. Can you get a directory of selected filenames or
types on the Commodore? Apple DOS doesn't do any wildcards at all (unless
you use FID).

-- Derek
Received on Wed Dec 16 1998 - 18:25:24 GMT