5 May
2009
5 May
'09
9:42 a.m.
On 5 May 2009 at 11:08, js at cimmeri.com wrote:
So clarify this for me. Someone figured that they
could squeeze more
out of a track than the IBM System 34 standard? How was this done?
By decreasing decreasing the gap lengths?
Exactly. After all, IBM did it--the original 160K 5.25" disks for
the 5150 were 8*512 and by DOS 2.0 had been expanded to the 9*512
180K format. It's possible to reliably fit 10*512 on a 2D 5.25"
diskette on a PC with reasonably "modern" drives, but the gaps get
very small. Many CP/M formats left off the IDAM to make room for
larger gaps when the 10*512 format was used, but that's not an option
for a stock 765-based controller.
On an 8" drive, the limit is 30 sectors for the 256 byte soft-sector
floppies.
Cheers,
Chuck