Re: CBM DOS 1.0 / CBM 2040, 3040 with 670 blk free

From: William Levak (wlevak_at_cyberspace.org)
Date: 2000-03-07 18:33:45

On Tue, 7 Mar 2000, [iso-8859-1] André Fachat wrote:

> I don't emulate the FDC side of the drive. Instead I monitor certain
> memory locations and do the stuff in C.

As far as I know, the 2040/3040 has never been fully documented.  The
relevant memory locations may not be the same for all functions.
 
> As I can read the DOS version/error message at least partially I assume
> that starting up works, and the bug is somewhere else (reading the error
> message should not involve the FDC)

"at least partially"??  That doesn't sound promising.  On the real drives,
reading the error message is a trivial function.

Since the DOS side waits for the FDC to respond to commands, failure of
the FDC side can cause strange results, at least in the real drive.  The
FDC also writes to memory that the DOS side uses.  It is possible for the
FDC side to mess-up the DOS side.


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