One approach to reading/writing hard sectored media would be to cook up a
firmware set for, say, a UBICOM SX MCU that would be tasked to sample the signal
coming from the drive and keep track of it with respect to the index/sector
pulses, which, of course, could then be on the same line, since there'd be no
FDC to get confused when they occur.
The simple way would be to shuffle the sampled data into a RAM that's 9 bits
wide, where the 9th bit would be the state of the index line. Software could
beat on the resulting sample to format it into sensible and convenient form
based on the vast oversampling done with the MCU. No hardware outside the MCU
would be necessary, since the SX52, say, could mux the addresses to the 256Kb x
9 DRAM in firmware in plenty of time and would still have enough pins for the
data and the disk I/O. The SX52 can drive an FDD cable without external
buffers, by the way. All it would take is a bit of code and a 48 MHz
oscillator. That happens to be a VERY convenient clock rate for this sort of
task, too.
Once a data massaging software set is whipped into line, the makers of TELEDISK
couldn't complain about infringement, since there wouldn't be any, yet you could
use the massaged data to rewrite the diskette image at a remote location once it
was fiddled with enough to generate the appropriate write precomp, if needed.
With an SX52 at a either 48 or 96 MHz, you could easily do this job,
irrespective of whether the data is in manchester, GCR, FM, MFM, etc, since the
analysis would be handled by the PC off-line. Meanwhile, the data just has to
be transferred.
These little MCU's cost about $8, IIRC. They're in a QFP with 0.65mm pin
spacing but that's quite common. At least one British company, and several
American ones, among others, make adapters to which they can be soldered and
subsequently put in to a PGA socket. Moreover, if you don't mind drilling the
holes, you can make such a thingie yourself.
Dick
----- Original Message -----
From: "Fred Cisin (XenoSoft)" <cisin_at_xenosoft.com>
To: <classiccmp_at_classiccmp.org>
Sent: Sunday, September 09, 2001 7:28 PM
Subject: Re: Vector 3/Teledisk
> > > Really?
> > > The Vector machines that I have seen have all been hard-sectored. I would
> > > LOVE to see a PC (running Teledisk, or ANY other software) be able to do
> > > anything at all except CHOKE on a hard-sectored disk.
>
> On Sun, 9 Sep 2001, Tony Duell wrote:
> > Am I allowed to do some hardware hacking? I see no reason why a PC with a
> > suitable card could not read a hard-sectored disk....
>
> Of course I meant a stock unmodified PC, with "normal" hardware.
>
> But yes, I'd love to have you make disk controllers for PC that can handle
> hard sectored, GCR, etc. It's certainly quite doable, but there isn't
> much of a commercial market for them.
>
> --
> Fred Cisin cisin_at_xenosoft.com
> XenoSoft http://www.xenosoft.com
> PO Box 1236 (510) 558-9366
> Berkeley, CA 94701-1236
>
>
Received on Sun Sep 09 2001 - 21:46:08 BST