Re: 8250 and C64 disks

From: Nicolas Welte (
Date: 2006-04-03 21:33:26

Hi Claus,

> --- Ursprüngliche Nachricht ---
> Von: Claus Just Rasmussen <>
> (2) I also noticed that the 4040 might actually be sick... or maybe only 
> modified - the 6532 is located on an extra socket (mounted in the 
> original socket) + a few wires are added. So... don't know if it works...

OK, I have a dead 4040 here that I might be able to repair. Might take a
while, though ... I will also read some docs on the 4040 memorymap and see
if there are any potential problems.

> > It went quickly through the disk (selected drive 0), wrote "0" at each 
> > sector (what's the numbers?), created a F80 file in current dir and 

The numbers are the job queue return (error) codes. They are defined by the
DOS ROM, and are mostly equal in all drives. You can look them up here:

I don't know what "0" is, it isn't listed there. 3 is a sync error (21, read
error), and 5 is a block checksum error (23, read error). My guess is that
the 4040 memory map is different from the 8x50 and that this causes all
these problems.

I will have a look at your nasty file creation problem. Did you try to
specify a filename without a path, so the current directory is used? I also
had no trouble when the current directory was in e.g. c:\diskimage and I
called the program from there, e.g. "c:\bin\imgrd testdisk".


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