29 May
2005
29 May
'05
10:22 a.m.
It was common practice to use 96 tpi drives for both
40 and 80 track
disks on BBC micro systems. If someone only had a 48 tpi drive and
couldn't read the disk written on the 96 tpi drive the usual solution
was to format it on the 48 tpi drive and then re-write it on the 96
tpi drive.
What good does that do? The 40 cylidner drive will write a wide track
when formatting, the 80 cylinder drive will re-write the middle of it
with data when you write to the disk, the 40 cylinder drive will then get
a mix of the data and the formatting pattern. That's the sort of thing
that _causes_ the problems
You'd be better off bulk-erasing the disk (with an AC-enegized
electromagnet, not a disk drive!), formatting it on the 80 cylinder
drive, writing it there, and the reading it on the 40 cylinder one.
-tony