[coreboot] v3 parallel port console?

[Peter Stuge]

Joseph Smith wrote:
> > Joe, I remember you were interested in crazy hardware hacks.
> > Would designing a floppy->parallel port interface (or
> > floppy->serial) fit your bill?
> 
> That would be a crazy hardware hack. I don't think it would be too
> dificult considering floppies are basicly serial devices. I'll do
> some research.

These are the signals:

http://hardwarebook.info/Internal_Diskdrive


> I think the hardest part would be a driver/software able to
> manipulate the floppy port for serial.

Not so hard, it will just be bit-banging the signals. I would suggest
using 8 output signals, one strobe out and one ack in to increase the
transfer rate.

The drawbacks are that timing and thus transfer speed will differ
with CPU speed and that it is relatively impractical to drive
communication like this.


I'd like to also nominate PS/2 for consideration, it already comes
with a serial transceiver (odd-8-1) and once the superio is
configured, writing one byte should need just a few io instructions.

http://hardwarebook.info/Keyboard_%286_PC%2C_PS/2%29
http://hardwarebook.info/AT_Keyboard/Mouse_protocol
and the PORTS file from
http://www.cs.cmu.edu/~ralf/files.html (search for K-P0060)

10-16.7 kHz it's kind of slow, but..


//Peter