roy@gitpyr.UUCP (Roy J. Mongiovi) (06/04/85)
I'm looking for info on how to determine the parameters necessary to
format a diskette with other than 8/9 sectors per track on the IBM PC.
DOS 1.1 supported 320K floppies with 8 sectors per track, DOS 2.0+ now
supports both 8 and 9 sector tracks. There seem to be three relevant
values in the disk parameter block:
DOS 1.1. DOS 2.0.
value value
block+4 number of sectors per track 8 9
block+5 read gap length 42 42
block+7 gap length for format 80 80
In other words, they stuck one more sector per track without changing the
gap size. How in the world does that work? Also, I know that J-format
from tall-grass (?) can format a 10 sector track. What values are needed
to do that? In general, how do you determine these values?
--
Roy J. Mongiovi. Office of Computing Services. User Services.
Georgia Institute of Technology. Atlanta GA 30332. (404) 894-6163
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The Map is Not the Territoryrde@ukc.UUCP (R.D.Eager) (06/16/85)
I suggest you take a look at the Intel data sheets for the 8272 (or even
better, the NEC ones for the UPD765). These tell you quite a lot.
A small point. I believe that there is no difference in the physical
formatting between disks formatted on DOS 2.x upwards with and without
the /8 switch. The difference is only in the BIOS paramter block in the
boot sector, which says to only use eight sectors/track. Of course, real
DOS 1.x disks do only have 8 sectors/track!
--
Bob Eager
rde@ukc.UUCP
rde@ukc
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