Re: Hardware Idea -> IBM drives on Apple //e,GS

[kpopple@imp.sim.es.com (Ken Poppleton)]

In article <CG3MsD.5Av@actrix.gen.nz>, dempson@swell.actrix.gen.nz (David Empson) writes:
> In article <5NOV199318435913@zeus.tamu.edu>
> a0m2504@zeus.tamu.edu (AKITOMO MORITA) writes:
> > A question to all you hardware gurus out there.  I've been toying
> > with the idea of making a card for the Apple //e or GS to use
> > IBM-style high density 5 1/4's and 3 1/5's by using one of the Floppy
> > Drive Controller chips used in IBM PC's.
> 
> There was a commercially available card for the II which did this.  I
> ...

You may be refering to the FDC-10 from CTI.  It supports up to four
drives of either 5.25 or 3.5 inch drives at 400k/800k formats.  If
there is interest I could post some information on the drive or Email
it directly.  This controller card is still avaible.


> 
> You would run into problems trying to support high density drives.  I
> think the bit cells are one microsecond apart, so you'd have to read
> or write a byte every eight microseconds.  This isn't feasible without
> using DMA.

The developer of the FDC-10 looked at doing a high density card, but decided
it was not worth the effort.  I guess not enough of the FDC-10's sold to keep
him interested in the Apple II market.  But he still does support the FDC-10.
It would have been a cached, DMA device.  This would be to allow the disk to
run at full speed and then send what is needed at a slower rate to the Apple.
He was also considering adding hard-drive support as that would have been only 
a small addition to the board once the data cache is there for the disk drive.

> 
> By comparison, the Apple II 5.25" drive uses 4 microsecond bit cells,
> and the 400k/800k 3.5" drive uses 2 microsecond bit cells.  A 1 MHz
> Apple II cannot cope with this speed using a software loop - the IIgs
> and IIc+ can do it, because they have faster processors.  Even the
> IIgs wouldn't be able to cope with 1 microsecond bit cells unless DMA
> was used.
> 
> The main thing you would need is software.  The card would need to
> implement a ProDOS and SmartPort firmware interface, and preferably
> have some special entry point for use by a GS/OS driver, which allowed
> multiple sectors to be read or written using a single call.


Yes, software is always a bottleneck, lots of hardware can be
developed but is not any use without proper software.  For the FDC-10
there is support for the ProDOS smartcard format.  This allows the
FDC-10 to operate just like any other Apple disk.  I use it as my
primary disk drive (two 3.5" 800k drives).  It is alot better than the
old DiskII I have, and alot faster!  What has not been completed is an
IBM-PC disk read/write program.  If a GS/OS driver were developed then
the GS/OS IBM FST would work (any volunteers?).  But is there really a
market?  Is it big enough to support a person?


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Ken Poppleton 
kpopple@imp.sim.es.com
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