8" floppy system needed to recover old game data

[Fred Cisin]

> > > data in a smaller area.  The highest density 8" media I ever had was
> > > DSDD, or 720K on the big 8" surface.  That's a LOT larger disk and
> > > hence a much
> > It was actually closer to 1.2M. In fact the 1.2M IBM PC/AT format is
> > almost exactly the same as a standard 8" format (it's the same data
> > rate, same rotational speed, etc), the main difference being that the
> > 8" drive has 77 cylinders, the 5.25" drive 80.

On Fri, 7 Oct 2005, Scott Stevens wrote:
> I was pretty keen on the drive space available to me back when I was
> running my BigBoard system (Xerox 820 clone) with two DSDD 8" drives.  I
> am almost certain the formatted capacity with CP/M was 720K with those
> drives.  I remember it so distinctly because when I 'upgraded' to a
> PC-XT clone, I was suddenly downsized to 360K per disk, exactly half the
> space.  Is it possible that the 1.2M capacity is like the 'advertized'
> 2M capacity that 3-1/2" 1.44 floppies sometimes have printed on them?
> Meaning, is that the raw unformatted capacity of the drive?

NO.
The unformatted capacity is about 1.6M.

Each track (77 tracks per side * 2 sides) can hold about 8 sectors of 1024
bytes each, or about 15 sectors of 512 bytes, or about 28 sectors of 256
bytes.

The ONLY difference in format between a DSDD 8" drive and a "1.2M" 5.25
(which were originally created specifically as a drop in replacement for
8"!) is: 77 tracks per side on 8" V 80 tracks on "1.2M" 5.25"


--
Grumpy Ol' Fred     		cisin at xenosoft.com