[coreboot] v3 parallel port console?

Carl-Daniel Hailfinger c-d.hailfinger.devel.2006 at gmx.net
Tue Sep 16 23:36:00 CEST 2008

On 16.09.2008 21:10, Joseph Smith wrote:
> On Tue, 16 Sep 2008 20:17:36 +0200, Peter Stuge <peter at stuge.se> wrote:
>> 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..
> My vote is for PS/2 also. There's a data and a clk line, so simple. The
> question is, newer motherboards are not coming with PS/2 ports, only USB
> (especially BTX). So Carl-Daniel how many of those boards have PS/2? Here
> is my favorite site to find out what devices have what signals (and pin
> outs): http://pinouts.ru/

All of them have PS/2. However, some only have one PS/2 port which is
either a pure keyboard or a combined keyboard/mouse connector. The
latter may pose challenges regarding pinouts and/or electrical
interfaces (multiplexing?).

Guys, have you noticed how similar this idea is to the often-derided USB
flash key plugged into a USB<->PS/2 converter? That's a great thing! It
means we'll attract all sorts of crazy hardware hackers.



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