Re: Pet 8088 coprocessor board for sale on Ebay

From: Marko Mäkelä <>
Date: Mon, 17 Jan 2011 21:04:51 +0200
Message-ID: <20110117190451.GA2637@x60s>
Hi Michał,

On Mon, Jan 17, 2011 at 06:42:43PM +0100, Michał Pleban wrote:
>If you look at the D80 file with a hex editor, you will see the FAT
>table starting at $0100, then FAT copy starting at $0300, then MS-DOS
>directory starting at $0500. Looking at the FAT contents and file sizes,
>I conclude that FAT clusters are of 2 kB size. But I can't quite figure
>out which physical sectors correspond to FAT clusters. There are some
>strange one, two or three-sector gaps filled with 00, and I can't
>comprehend that.

This sounds like the Commodore CP/M disk format, which (in the C64 Z80 
cartridge or in the C128 or both) reserve a fixed number of sectors per 
track. A long time ago, I implemented support for the Commodore 128 CP/M 
disk format in cbmconvert. You might find that useful.

>BTW, yes, I took the D80 file I got from Ed Shockley, and I put in onto 
>a diskette to make a bootable disk. I did it with cbmlink, there were 
>no problems with that.

cbmlink just copies disk images sector by sector, doing nothing fancy.  
It steps to the next track when it gets an 'illegal track or sector' 

Best regards,


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Received on 2011-01-17 20:00:08

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