Dave Tweed <pic <at> dtweed.com> writes:
> > May I ask what type of PIC was able to write and read raw clocked bits
> > at 2MHz or 4MHz bit rate ?
> What kind of floppies do you have?
> All the standard ones I'm aware of run at 250 or 500 kbps, including the
> ubiquitous 3.5" 1.44 MB size. There were some very early 5.25" and 3.5"
> drives that ran at 125 kbps.

I think that I confused the data recovery PLL clock with the bit rate. Anyway I
was thinking about a DRAM because it is 1 bit wide. I suppose that one could try
to use a MC/SD card or directly NAND flash in a similar way instead (don't know
about write speed). My interest lies esp. in making a gizmo that can appear as a
bootable 1.44MB floppy to a motherboard through a standard floppy connector. 
Write is not necessary, and capacity need not be a full 1.44MB. This would be for
the plethora of boards that refuse to bot reliably from USB sticks.

Even at 500kHz data must move 'into' the PIC every 2usec. This is fairly fast 
esp. if it needs to be de-serialized (not necessarily 8 bits wide - I do not
remember the width of sector marks and start sequences on floppies) and then
written into SRAM.

thanks for the answers,
Peter P.



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