On Wed, 10 May 2000, Alan B Pearce wrote:

> Date: Wed, 10 May 2000 09:37:15 +0100
> From: Alan B Pearce <A.B.Pearce@RL.AC.UK>
> Reply-To: pic microcontroller discussion list <PICLIST@MITVMA.MIT.EDU>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: very [OT] linux masquerading a lan
>
> >Just make the Flash sit there and look (to the on-motherboard FDC) like
> >it IS a (small) floppy drive.  Add a 4-pin power connector and far as
> >the machine knows, it has a write-protected Floppy in the drive.  The
> >FDD is a lot dumber, easier to reverse engineer part than the FDC,
> >methinks, and FDC's are pretty universal (Also, you don't eat up a
> >sometimes non-existent ISA slot - you don't have to deal with PCI -
> >etc.)
>
> The problem here is that you need to have the data come out as a serial bit
> stream with a properly appended CRC code. the data also needs to be encoded as a
> MFM data stream. If the PIC does the parallel -> serial conversion, I suppose it
> would be practical to append a couple of bytes of precalculated CRC to the data
> sector in the flash, but this would then mean a fancy calculation to find the
> start of the next sector.

Ah, I believe it's worse than that: you'd need to generate synch fields,
header bytes, sector gaps. The pulses from the index hole. If you're
halfway through playing out sector 7 when the controller switches the
head, you really oughtta now be in the middle of sector 7 on the other
side. Etc.

How about building with an IDE interface and boot as C: (or /dev/hda or
whatever), this is supposedly what IDE is for?

-- Rich