26 Jul
2005
26 Jul
'05
2:45 p.m.
On Tue, 2005-07-26 at 19:15 +0100, Pete Turnbull wrote:
Well that bit's easy then :)
I did just get to puzzling about what sort of sampling rate would be
needed to properly record data from the controller. I suppose the device
just needs enough memory per "track" to match the bit density * platter
circumference of whatever drive's being simulated.
cheers
Jules
On Jul 26 2005, 14:42, Jules Richardson wrote:
I suppose that's possibly not relevant for a solid-state replacement
though, as the device's ability to virtually step tracks will be far
faster than any controller of the period would produce?
I'm not sure how complex such a box would be.
I *think* an ST506-
interface drive looks pretty much like a big floppy, just with more
heads. Far as I know, it doesn't do anything intelligent on the drive
itself, just responds to head select / step commands from the
controller
and reads or writes data.
Yes, except normally the step pulses are buffered, so you can send them
fast and the drive will handle them at the correct rate. At least, all
but the oldest drives do that. That's the main difference between
ST506 (not buffered) and ST412 interfaces. The bit I
don't know is the nature of the data signal at the interface -
it uses +/- signal lines for both read and write data. I'm not sure if
that's an analogue signal or a digital one.
Digital. I don't
think there's a need to handle anything complex in the virtual
drive. I believe an ST506 drive's purely a data store/replay device and
it knows nothing of the actual data stored on it - most of the circuirty
on board is presumably just motor control and head amplifiers / filters.
Correct.