"intelligent" disk drives

[Jim Brain]

Ethan Dicks wrote:
> On Sun, Nov 18, 2007 at 10:11:14PM +0000, Tony Duell wrote:
>   
>> It's been a long time since I used one of these 'in anger' but wasn't 
>> there an issue witch copying one of the random-access file types between 
>> disks? (or maye between disks in different drive units). If I'm 
>> rememebring correctly, it means the converting between 4040 and 8050 
>> disks is a pain even if you haev both drive units .
>>     
>
> My recollection is that in general, CBM DOS "relative" files weren't
> particularly portable from DOS version to DOS version.  I think you
> had to understand the record structure and copy them one record at
> a time.  I think you might have been able to copy relative files from
> one diskette to another in the same drive unit, but I never tried it,
> so that's a faint memory and mere speculation.
>   
4040 and 2031 REL files were portable to 1540/1541/1571 if one simply 
read the records and wrote them out.  Writing it sector by sector 
probably would have worked as well, but I have not done research.

8050 and on up (8250, SFD, etc.) use Super Side sectors, which made 
sector copies impossible, and I think record copies only possible if the 
number of records was under a sertain limit.

As I recall the 1581 used an entirely different scheme for REL files, so 
all bets are probably off on that unit.

Jim


-- 
Jim Brain, Brain Innovations                                      (X)
brain at jbrain.com 
Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times! 
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