31 Oct
2006
31 Oct
'06
9:26 a.m.
Since this list has a number of people that are very knowledgable on the
subject :
Am i correct in thinking that, given a custom FDC, i could run a modern
1.44 floppy in FM mode, and at much lower data rates i.e. (say 50 KHz.) ?
Background : I am musing on how to give a small amount of storage, say
around 100kb, to a very small low tech cpu.
I do not care about speed and efficiency.
I am aware that IDE-based solutions are simpler, both hard- and software
wise, but I would prefer a floppy based solution.
Jos Dreesen
31 Oct
31 Oct
3:44 p.m.
Since this list has a number of people that are very knowledgable on the
subject :
Am i correct in thinking that, given a custom FDC, i could run a modern
1.44 floppy in FM mode, and at much lower data rates i.e. (say 50 KHz.) ?
You;ll have no problem with using FM, but I thought there was a minimum
data rate requirement too.
Certainly the read output will give a fixed-width pulse for every flux
transtion on the media (so don't expect the read data output to
faithfully reproduce the pulses you fed into the write data line, in fact
just the leading edges will be preserved). I had an idea that if the flux
transitions were too far apart then some part of the read chain got
confused, but maybe not.
-tony
5:03 p.m.
On 31 Oct 2006 at 23:44, Tony Duell wrote:
Certainly the read output will give a fixed-width
pulse for every flux
transtion on the media (so don't expect the read data output to
faithfully reproduce the pulses you fed into the write data line, in fact
just the leading edges will be preserved). I had an idea that if the flux
transitions were too far apart then some part of the read chain got
confused, but maybe not.
I know that most drives have low-pass filtering on them, but I'm not
so sure about high-pass. The OP was asking about a 50 KHz data rate,
which I think is probably within the bandpass of most drives, at
least at the double-density (250K) rate. I do recall that some older
drives using the MC3470 read amp will belch out a false read pulse if
it's been too long since the last one.
Cheers,
Chuck
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