[posted and mailed]

"Bill Garber" <willy4SPAM6pa@comXcast.net> wrote in
news:yi6dnXdE4oBdNh6iU-KYvQ@comcast.com: 

> Well, that explains my other question. I wondered why Mr. Watson
> didn't simply patch the MSDOS.FST, and now I know. There is no
> info on it to know where or how to do it. Sourcerer won't disassemble
> the whole file. Just the first 0000-004F of it. I wonder if I can
> change the Object Module ID so it will disassemble the whole thing.
> Maybe a simple filetype ID change. Hmmmm, let me see what I can do.

I've never, at least not recently used Sourcerer.
Considering most GS programs use the Object Module Formated files why not 
use a GS aimed disassembler such as the ORCA/Disassembler?
(That's what I used when I was debugging the Appleshare CDEV.)
It even has a minimal FST header script (that seems to have just a few 
errors).

Unfortunately FSTs may be making even more undocumented calls to GS/OS 
and ROM, that although they are stable, may make figuring out the code 
difficult.

This snippet is from the script and a little manual correction of the 
start of the MSDOS.FST ~main segment.

;
; Predefined labels:
Dev_Dispatcher gequ $01FC00             make device driver call
Swap_Out gequ  $01FC34                  mark volume as off-line
Cache_Flsh_Def gequ $01FC54
Move_Info gequ $01FC70                  move data between buffers
         dc    c'FST '                  FST signature
         dc    i4'L0073'                call handler entry point
         dc    i4'$0151'                GS/OS internal entry point?
         dc    i2'$000A'                file system ID
         dc    i2'$8802'                attributes
         dc    i2'$0100'                version
         dc    i2'$0200'                block size
         dc    i4'$00010000'            max volume size (blocks)
         dc    i4'$00000004'
         dc    i4'$FFFFFFFF'            max file size (bytes)
         dc    i4'$00000000'
         dw    'MS-DOS'                 FST name
         dc    h'1C'
         dc    c'MS-DOS FST            v01.00'
         brk   $00
         dc    c'(MS-DOS FST written by Greg Bran'
         dc    c'che V1.00'
L0073    entry
         phk
         plb
         LONG  I,M
         cpx   #$0067
         bcs   $007F
         jmp   ($015D,x)
         lda   #$0001
         sec
         pha
         php
         bcc   $00A9
         lda   $1FAA
         bpl   $00A9
         ldx   #$1432
         ldy   #^$02/1432
         lda   #$0000
         jsl   >$01FC48
         bcs   $00A9
         jsl   >$01FC38
         stx   $98
         sty   $9A
         lda   [$98]
         jsl   >$01FC28
         jsl   >$01FC6C