7 Dec
2006
7 Dec
'06
3:09 p.m.
> I don't know enough about how floppy
interfaces work, but I know enough
> about microcontrollers to see this as being a "not too difficult" project
> from the hardware side. Coding it might be difficult, getting all the
> timings right.. but it certainly does not strike me as "impossible".
Jules, seems that it is easy enough. I already started to do some
experiments. In my proposition of the three-layers, the first and second
layers are almost done. I just need to dig deeper into the floppy innards.
Shuggart interface specialists around? :o)
For me it HAS to emulate the physical drive, and not the OS/formatting
of the target. If you have a bit more work to emulate the physical drive,
you'll have a universal device. What about a group digging into that?
If I knew anything about PIC design* I'd get to
doing some messing around
with it right now... :-)
www.mcselec.com - download BASCOM-AVR and get some Atmega32 or
Atmega128, you'll have a great surprise of how easy is to use that.
* assuming that a PIC is fast enough; it'll have
to read/write to the
floppy interface side at several times the floppy data transfer rate, so
several MHz - then there are program overheads on top of that... (you
could almost do a DMA approach to/from buffer memory actually and have the
CPU relatively slow...)
AFAIK, the "mechanicals" of the drive can be separated into two points:
- Mechanical control and sensing: track up/down, motor on/off, select
head 0/1, index hole, disk change, density select
- Logical encoding of MFM data: get raw sector data, output MFM-encoded
data
The first is a breeze. The second I have no experience but seems easy
enough by what I saw on wikipedia. I have a "digital alignment disk" for 3
1/2 720K floppies. Since the data on this disk is know (and have no
sector/track encoding, just raw data), I'll try to read and understand that.
If someone is willing to help, contact me privately. I'm using AVR
microcontrollers and the Bascom compiler. I'm looking for the shuggart
manual of the disk interface (ST-406?).
Greetz from Brazil
Alexandre Souza