floppy controller IC (was Re: Fixing a PET?)

From: Glenatacme_at_aol.com <(Glenatacme_at_aol.com)>
Date: Wed Sep 29 23:36:33 1999

In a message dated 09/29/1999 3:04:36 PM Eastern Daylight Time,
ard_at_p850ug1.demon.co.uk writes:

> > 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
> I assume that's total number of tracks, or something similar.

Yes, the total number of tracks.
> LDOS (and related OSes) on the TRS-80s does much the same thing. When you
> format a disk it asks you for the number of sides and number of tracks.
> And provided the hardware is capable of handling what you ask for, it
> will format and (correctly) use the disk.

Interesting -- I'd _not_ be shocked to find out that the maker of the system
I use "borrowed" the idea from RadShack.

BTW my understanding is that all 5.25 diskettes made today are bin-sorted --
that is, they shoot for DSHD and the fallouts are sold as DSDD. I have a
number of "DSDD" diskettes here which work well when formatted with 50+
tracks, although how this is possible with "40 track" DSDD drives I haven't a
clue. Perhaps you do.
> On the model 1, the original drives were 35track, but all later ones
> could do 40 tracks (or a little more, like 42 tracks). Needless to say,
> the extra storage, particularly on 'system disks' came in handy back then
Fortunately this system doesn't require "system disks" (the os is on an
eprom) but I know what you mean. In a floppy based system a few extra KB can
_really_ make a difference ;>)


Glen Goodwin
Received on Wed Sep 29 1999 - 23:36:33 BST

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