Building a floppy drive interface

Hi

I'm looking for some docs about how PC/AT floppy interface works and
how can
I build a floppy drive interface to be attached to PC parallel port. I
know how
parallel port works, even built some circuits connected to it.
My interests a pinout, levels (should be TTL), protocols, etc.
I've been searching at epannorama.net but those docs just explains
basically cabling.
This is my hardware project to a college class.

Can anybody please point me out to some good tecnical documentation
about it?

thanks a lot in advance.

Lucas Brasilino

Previously Lucas Brasilino wrote:
Hi

I'm looking for some docs about how PC/AT floppy interface works and
how can
I build a floppy drive interface to be attached to PC parallel port. I
know how
parallel port works, even built some circuits connected to it.
My interests a pinout, levels (should be TTL), protocols, etc.
I've been searching at epannorama.net but those docs just explains
basically cabling.
This is my hardware project to a college class.

Can anybody please point me out to some good tecnical documentation
about it?

Best start by reading the docs of the controller chip. You should be
able to get a discrete one. Some info he

http://home.swipnet.se/~w-68269/wd_fdc/wd_fdc.htm

on using a WD chip. I believe the original floppy controller from the
AT is the NEC µPD765. You might want to google for it.

It might be difficult to get these chips today, since for a long time
they have been integrated into multi-I/O chips.

I think you should be able to read/write/format with a directly
connected high-speed microcontoller, such as a 33Mhz DS 87C520 WCL,
but that would mean implementing the whole FDC in software. That
could be rather messy and take long.

I think your best approcha is tho first find out what chips you
can actually get and then selet the one that needs the
easiest interface logic and the least programming.

Arno
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