FDCs (was: MITS 2SIO serial chip?

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Mon Dec 17 20:59:51 2001

There ARE many things that the WD will do that the NEC won't, including
writing much sooner after the index pulse, IGNORING certain fields in the
sector headers when reading, and a track read and write (the NEC has a
multi-sector read and write instead of a track R/W)

Allison could probably gives us a more comprehensive and authoritative
list.


On Mon, 17 Dec 2001, Richard Erlacher wrote:
> Gee! ... and I let those guys at Western convince me you couldn't do that.
> I've never attempted anyting with Int13, BTW, since I don't hack the PC's. I'm
> afraid to break something. I've got a '765-based machine I can experiment with,
> though.
> Dick
>
> ----- Original Message -----
> From: "Fred Cisin (XenoSoft)" <cisin_at_xenosoft.com>
> > Yes, you can. Correction. I, and others, can. I shouldn't claim that
> > you can.
> > But Int13 won't. That is NOT the same as the chip not being able.
> > You need to assemble an array of the sector headers that you want.

> > On Mon, 17 Dec 2001, Richard Erlacher wrote:
> > > There's one advantage that you can exploit with the WD parts that the NEC
> parts
> > > won't support, and that's formatting with interleaving. The NEC parts seem
> to
> > > be unable to format a diskette with other than strict ordinal sector
> numbering,
> > > while the WD allows you to number them with any offset you like. The result
> is
> > > that an interleaved format optimized for one set of system parameters can
> still
> > > be read by another system without the other system having to be adjusted in
> any
> > > way. Of course it won't be able to read an entire track in one revolution,
> but
> > > it will have the ability to read the diskette without introducing a modified
> > > lookup table for sector numbers. I know that doesn't make much difference
> > > nowadays, but back when folks used floppies as their main/only storage
> medium,
> > > it impacted performance.
> > > Dick
Received on Mon Dec 17 2001 - 20:59:51 GMT