Re: What is the most used ROM in the brown 1541?

Date: Thu, 18 Jun 2015 20:11:06 +0200
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Hallo Julian and everyone else,

> I wonder just what your reason for the question is....

First a remark on forehand: quite some I time ago I read "Inside 
Commodore DOS" and that book mentioned that you couldn't exchange 
floppies between a 1541 and a 4040. I never had problems with 
exchanging floppy disks between the brown 1541, 1541C, 1541-II and 
CBM 4040.

I'm still busy with commenting the sources of the various ROMs and I 
noticed that in version 901229-03 the number of bytes in the header 
gap was increased from 8 to 9. This meant that 9 is also the value 
used in 901229-05, -06AA and the 1541-II. And this is the value that 
was already present in the CBM 4040. 

So it seems it was changed to 8 for the 1540 for one or another 
reasons. I have a 1540 but, to be honest, I never used it for 
programming, testing etc., etc.: I considered it too much as an 
collectors item. The rest of my 1541s have all been equiped with the 
05, even the older long-boards (not done by me). And I wanted to 
know if this was a coincidense or was the 05 more wide spread than 
anything else.

Except changing the checksum, changing the size of the header gap at 
two places was the only change of version 03. And these 9 bytes 
triggered me to remember the book. And as said before, I never had 
any, any problem at all so I thought the author must have it wrong 
in one or another way. But what?
It now seems that the author must have been testing using a 01 or 02 

After remark: this afternoon I got the idea to check my spare 
storage and that gave me another conformation of what is the most 
used ROM inside the 1541: I _only_ have 901229-05s ! 

Kind regards / Met vriendelijke groet, Ruud Baltissen

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Received on 2015-06-18 19:00:07

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