On 9/1/22 19:22, Fred Cisin via cctalk wrote:
But, how about a WD TRACK READ with the index pulse
masked?
Well, okay, but I never found that to be very useful, because to achieve
correct byte alignment, you need one of the standard address marks to
get the data separator working right, which few HS recording schemes
employ. That's not to say that it can't be done, but it's a lot of
trouble, particularly for MFM encoding. There's also the dodge on PCs
of using two drives--one with a standard formatted soft-sector floppy to
start a "read track with a very large sector length code" operation and
changing the drive select to the second drive while the read's in progress.
The "Read Track" feature is useful for recovering data from regular
soft-sectored IBM System/3 or 3740-type floppies, however.
All in all, a cheap MCU is easier--and cheaper, I think. Consider a
little STM32F405 MicroPython board--it runs at 168MHz, timers that can
capture pulses at 84 MHz and has about 192KB of fast SRAM inside. Cost
is around $11-15 and includes MicroSD and USB interfaces.
Similarly, you can get an Option Board working on index-less or
hard-sectored floppies by using a cheap MCU to either generate or mask
index pulses. You can even use the same MCU to simulate index pulses
for equipment requiring hard-sectored floppies. A little 8-pin <$1 MCU
is more than adequate for the job.
Silicon has gotten so cheap!
--Chuck