Re: New idea HD for C= and 1541 ROM Listing

From: Ethan Dicks (
Date: 1999-09-06 18:17:50

--- Richard Atkinson <> wrote:
> Does anyone know how filetypes (PRG, USR, SEQ and REL) are implemented?

Implemented how?  The difference between a PRG file and an SEQ file (besides
the bit in the directory entry) is that a PRG starts with the load address
as a low-byte, high-byte pair.  USR files are undefined by CBM DOS, and REL
files are different depending on the exact version you have (super-side-sectors
and the like).  There's lots of code in every drive to support relative files.
I've writted professional code to manipulate them, but at this point in
history, I don't think the amount of coding required to continue to support
them is worth the payback.  Has anyone ever used them for anything more 
interesting than a simple index file, a la electronic Rolodex?


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