Re: S FIles

[dempson@actrix.gen.nz (David Empson)]

Tim <secretguy@altavista.com> wrote:

> I saw some of you guys talking Applesoft awhile ago.  I had a problem
> awhile back-- well, more of a determination-- that I couldn't figure
> out.
> 
>   There are A files.  (RUN HELLO)
>   And B files (BRUN PACMAN)
>   And then I found.... the S files.
> 
> I have one disk-- only one in my collection of hundreds-- that was
> made my Orange-Apple-COmputer-Club (or something like that) that, when
> you type catalong, you get S Files.  The S files seem to be used
> almost as REM statements in the Catalog.  Kind of like this:
> 
> ]Catalog
> 
>   Disk Vilume 254
> 
> S 000  ===================
> S 000  Welcome to Our Disk
> S 000  Enjoy all the Programs
> S 000  ===================
> A 012  HELLO
> A 014  NEWGAME
> 
> etc...
> 
> My question  How do I make a 000 byte S file appear in my disks'
> catalog?!?  That is so cool!!

There isn't any way to directly create or access "S" type files from the
command prompt (the same goes for "R" and the alternative "B" and "A"
file types).

The full list of file types is given by the string "BARSBAIT", which is
visible in a dump of DOS 3.3.  The characters correspond to each of the
bits in the file type byte in the directory entry, with the exception of
bit 7 (used for the locked flag); "T" is file type zero.

I don't recall offhand how DOS interprets a file type byte with multiple
bits set - I think it displays a question mark instead of one of these
letters.

The last four types (B, A, I and T) are the standard Binary, Applesoft,
Integer and Text files.

I have no idea whether Apple decided what "R" and "S" were supposed to
be when DOS was being designed, but "R" was eventually used for
relocatable files output by Apple's Editor/Assembler (EDASM).  "S" files
have a variety of nonstandard uses.

I'm not aware of anything using the alternative "A" type, but the
alternative "B" type was used by the LISA assembler for its source files
(with a patched version of DOS which changed the filetype character to
"L" to avoid confusion with the standard "B" files).

In general, the only way to use these nonstandard file types is to
bypass the command prompt and use one of the lower level interfaces
provided by DOS, such as the File Manager, or use a utility program
which lets you patch the disk directly.

As for creating zero-length files, that cannot be done with any standard
DOS call, only by patching the directory entries using a utility
program.  (Some files with a claimed size of "000" are actually 256
sectors in lengthw, but that isn't likely in this case.)