floppy controller IC (was Re: Fixing a PET?) - test-drb@ccmp.vtda.org

28 Sep 1999

In a message dated 09/28/1999 5:53:47 PM Eastern Daylight Time, 
ard(a)p850ug1.demon.co.uk writes:

...
  In general the older full-height 5.25" drives are
pretty slow at 
  stepping, and may even require 30ms between pulses (some older controller 
  cards/OSes always used this timing 'to be safe'). Half-height drives, or 
  3.5" ones tend to support faster step rates. The only way to be sure, 
  though, is to check the specs of the drives that you are using. 
Thanks again!  This is valuable information for me.  I've got bins full of 
half-height 5.25" drives here, so if worse came to worse and I had to replace 
the 1770 with a 1772 I'm certain I could come up with a compatible drive.

Interestingly, with this system when a disk is formatted it is required that 
the number of TPI be input.  This is then stored on the disk so I might have 
one 5.25 DSDD disk with 40 TPI, and another with 50.  The maker of the system 
says that it will support drives up to 255 tracks per side, "if the drives 
themselves ever do."

Anyway, thanks as always --

Glen Goodwin
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