Date   : Sun, 20 Jun 2004 11:45:54 +0100
From   : Philip Blundell <pb@...>
Subject: Re: PC/Econet

On Sun, 2004-06-20 at 10:40, Jules Richardson wrote:
> I was actually wondering if a PC parallel port had enough speed to just
> drive one of the Master-type Econet modules. Raw-speed-wise I think it
> should have, but timing could be a problem due to the nature of the
> polled-IO approach to driving a parallel port. Another back-burner
> project I'd like to fiddle with sometime though...

Yeah, it'd be interesting to try.  Data throughput probably wouldn't be
much of a problem, but again I suspect latency might be an issue.

Firstly, the ADLC only has small FIFOs, and you obviously have to be
able to load and unload them in a timely fashion to avoid
overrun/underrun conditions.  Secondly, the Econet protocol requires
that you be able to achieve a short turnaround time after being
addressed by a scout packet.  If the transmitting station sees the line
go idle, it will give up and report a 'not listening' kind of error.

All that said, though, if you're only talking about a clock rate of a
couple of hundred kilohertz, it might not be a problem at all on a
modern machine.

I guess it'd be easy enough to build a interface and try it out.  Maybe
I'll have a go at that.

p.