[Coco] Re: Drive speed incompatibilities

[Gene Heskett]

On Thursday 13 November 2003 11:51, Torsten Dittel wrote:
>> [...] That and the possibility the old drive is a
>> 40tpi, and the newer drive has 80tpi width heads.
>
>I don't remember that exactly but I think my father once added a
> "double step circuit" to 80-track drives. Could this be possible?
>
>Torsten

It can be automatic under os9, Torsten. You can make it work right, 
once you've set the descriptor with dmode and saved it.  The keyword 
for dmode is DNS, should be set for 3 if the drive is a 96tpi hidens 
model.    Then when later cc3disk modules look at the descriptor, and 
compares it to sector zero of the disk, if it finds a descriptor that 
says the drive is an 80 track, 96 tpi drive, but reads a sector zero 
saying its a 48 tpi disk, the double stepping is then automatic.  You 
may have to edit (use dEd) bytes $10, and $43 on the disk to reset 
the correct values there, but be sure and do the disk editing in a 
drive that is natively carrying the same width heads as the disk was 
originally written with.  Otherwise there is a 200% chance of 
trashing the disk.

For regular rsdos, you may have to build your father circuit again.

-- 
Cheers, Gene
AMD K6-III at 500mhz 320M
Athlon1600XP at 1400mhz  512M
99.27% setiathome rank, not too shabby for a WV hillbilly
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Copyright 2003 by Maurice Eugene Heskett, all rights reserved.