10 Apr
2007
10 Apr
'07
10:16 a.m.
On 10 Apr 2007 at 9:38, Philip Pemberton wrote:
I'm quite tempted to make the sync word
configurable, so you could sync on any
8-bit MFM sequence you liked. I know there's at least one other 'missing
clock' sync word in common use (IIRC it's 0xC1 with a missing clock in the
second nibble).
Too many years ago (probably about 12 or 13), I did a similar lashup
to decode some Smith Corona 2.8" diskettes. I used a WD9216 8-pin
data separator and a 2660 USART that I had kicking around in my
hellbox. Since the 2660 allows for a double-byte sync character, it
was pretty easy to find address headers using the sync "hunt"
feature. IIRC, I don't recall if the format relied on missing sync
pulses for AMs.
These were oddball diskettes--you started a read and the head swept a
spiral across the entire diskette, then returned to the beginning
automatically. A CW wouldn't have worked, because of the volume of
data in a single read operation.
Cheers,
Chuck