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Old 20th May 2021, 6:56 am   #16
mole42uk
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Join Date: Aug 2010
Location: Resolfen, Wales; and Bristol, England
Posts: 2,588
Default Re: 80-BUS Loft treasure?

Quote:
Originally Posted by ortek_service View Post
Quote:
Originally Posted by mole42uk View Post
First results are mixed- the XP machine sees the drives as 3½” jobbies even after I’d altered the BIOS.
Is that because PC's never really used 5.25" 720KB drives? - The most common types being:

5.25" 40T D/S - using Double-Density for 360KB
5.25" 80T D/S - using Hi-Density for 1.2MB (+supports lower Double-Density 360KB 40T discs, with double-stepping)
<snip>
But if these TB-504 drives weren't from a PC, then might have ensure drive-select is set to 1 and cable has twist to use for A: drive
According to the User Manual these are 80 track double-density double-sided drives which are specified as 1Mb unformatted, 656kb formatted. Neither drive was originally used in a PC, both were from a CP/M system so they may just not be compatible with the rather limited hardware options from a Windows-based machine.

The XP sees them as 3½” drives and spins the motor at the correct time, but fails to see that there's a disk inserted.
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