Re: 8250 and C64 disks

From: Claus Just Rasmussen (
Date: 2006-05-24 19:57:49

Hi Nicolas,

Seems that I might be able to get my hands on another 4040 instead of 
the one I used.

Question is - do you think that your current IMGRD works with 4040? (or 
in other words - if my problems reading my 4040 disks are probably 
caused by my 4040, then I'll try another one if possible. If not, then 
I'll wait :-)


Nicolas Welte wrote:
> Nicolas Welte wrote:
>> 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".
> The problem was caused by having only 8 character reserved for the 
> filename. You are supposed to enter only the name, without a path or 
> extension. The extension is added automatically based on the disk type.
> I "fixed" this and you can now specify a path as well. The version can 
> be downloaded here:
> I had a look at the 4040 problem as well. It seems I use a ROM vector 
> that does not exist in the 4040 DOS. I will have to rewrite my code to 
> use RAM variables directly, because the RAM locations are equal enough 
> in all dual drives. At least I hope so.
> I also tried to repair my 4040, without success so far. I checked the 
> following:
> 1. repaired power cable
> 2. 3 blinks. $E DOS ROM bad, replaced.
> 3. 5 blinks. checked 6504 (swapped with a printer). checked 6530 
> (swapped with SFD1001), even made a 2716 EPROM for the adaptor board 
> from the SFD. No success.
> Does anyone have an idea what can cause 5 blinks on a 4040 besides the 
> disk controller CPU (6504) and RAM/ROM (6530)?
> Nicolas
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Claus Just Rasmussen, BSc.EE.

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