21 May
2013
21 May
'13
1:19 p.m.
On Tue, 21 May 2013, Liam Proven wrote:
This might be a silly question...
Since the specs of the MGT +D disk interface are now out there in the
public domain...
http://www.worldofspectrum.org/NotThePlusD/
... but 720kB 3?" floppy drives are getting rather scarce, I was
wondering... would it be viable to build a version that supported
1.4MB "HD" drives? I realise this would mean a different FDC chip,
WHY?
I know few 8-bits supported HD disks, but I don't
really understand
why. My electronics knowledge is poor. (Cue Tony Duell.)
Tony can address electronics, but the immediate OBVIOUS reason why is
HISTORY.
HD diskettes came about AFTER 8 bits were going, going, almost GONE.
Few 8 bit machines were around when 3.5" drives came out, and fewer when
HD.
I am guessing that an 8-bit would struggle to
read/write data fast
enough to keep an HD diskette controller supplied with data, but I was
wondering if that could be overcome with interlacing or adding some
cache RAM?
Got DMA?
8 bit is not the issue. Many 8 bit machines handled 8" double density
which is exactly the same requirements (other than cabling and pin-outs)
as HD 5.25" or 3.5"
This is probably a completely pointless exercise -
people seem more
interested in using CF or SD media these days, but I enjoy the
nostalgic element of actual floppy diskettes.
It's not pointless if you enjoy working on it.
This is a HOBBY.
It is s'posed to be pointless.
--
Grumpy Ol' Fred cisin at xenosoft.com