USB Universal Floppy Disk controller
julesrichardsonuk at yahoo.co.uk
Fri Mar 11 11:16:20 CST 2005
On Fri, 2005-03-11 at 07:51 +0000, Philip Pemberton wrote:
> In message <1110504341.4413.91.camel at weka.localdomain>
> Jules Richardson <julesrichardsonuk at yahoo.co.uk> wrote:
> > But yep, agreed. I certainly need *something* that can archive / restore
> > classic formats to/from modern(-ish!) media.
> Shift register + counter + high speed RAM. Could even do it with an FPGA if
> you wanted.
> Buffering an entire track with 8x oversampling is going to be hellishly
> memory intensive though.
Well if worst-case is 1mbps data rate at 300rpm and 8x oversample, isn't
that (8 * 10240 * 1024) / 5 = 1677722 bits of memory maximum needed?
(div by 5 because 300rpm gives you a whole track in 1/5 of a second)
So 256KBytes of RAM should always be enough to buffer a whole track,
regardless of what physical drive or media you use.
Presumably there's no need to have any kind of microprocessor control;
it can all be done with a free-running clock to read from the drive or
write to it, and a few control lines to for read/write, start, stop etc.
Can static RAM can't cope with these kinds of speeds? Presumably cache
chips pulled from old PC motherboards would cope happily, even if old
80's parts wouldn't.
It's probably still beyond my abilities to design something that'd
work :-) But on the surface it doesn't sound *that* complicated for
someone who's used to designing digital circuits.
> > 3) aren't taking any backups at all! :-)
> Aaghh! That reminds me - it's a good year since I backed up the HDD on my
> machine... [fx: hard drive starts going kaclunk-kaclunk-kaboooom]
Oh boy. I rsync data from my desktop to an external hard disk
periodically (usually once or twice a week). Hadn't done it for a few
weeks, kicked off a run the other day, and the wholse SCSI subsystem
Panic for a moment, thinking my desktop drive had died. Turns out I'd
set the SCSI data rate to the external disk higher than normal when I
was playing around with something else, and forgotten to set it back
again - so it was just a SCSI bus transfer problem, not a hardware
More information about the cctalk