Cromemco 4FDC, How do you format a disk?

From: Allison J Parent <>
Date: Thu Jul 29 19:48:48 1999

<But from my measurements, I think that it's very unlikely that a drive
<can tell FM from MFM. I will try it sometime to confirm this.

True, but the timing is still important.

The SPEC I have for a Sony MP-F17W-70D (11/1988) makes it pretty clear
that the acceptable rates are 250/500kBITS/Sec MFM with no discussion
of plain FM. So it's probable the 8" SD rate of 250kbits/sec would
work. The 5.25" floppy single density rate of 125kBITS/sec clearly would
fall below the spec. There are limits to the write pulse width as well
but I'd bet the 1771 meets them as they are fairly narrow range for all
data rates and formats.

Keep in mond most all of the floppies I know of do have a minimum due
to the read amps bandwidth (there is a banpass filter!) and the
differentiators used to recover the read data. the head gap width also
sets the minimum data rate as well though to a lesser extent.

The easiest was to see this is record a track at different rates from
50khz through 1mhz and look at what comes out (or not).

Received on Thu Jul 29 1999 - 19:48:48 BST

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