Re: Buffering prlink cables

From: Marko Mäkelä (
Date: 1998-03-25 16:46:04

On Wed, 25 Mar 1998, MagerValp wrote:

> As I've already toasted one computer with prlink (my A1200 with sur-
> face mounted CIAs :P) , I thought I'd try to buffer my prlink88 cable
> before I toast something irreplacable.

First a question: Is your Amiga properly grounded?  If not, a voltage of
approx. half the wall outlet voltage (in your case 110-120 volts) can be
generated between the ground levels of the computers.  Connecting the
ground pins first, or switching off everything before connecting or
disconnecting any wires will usually help.

> So a question for Marko and Olaf: Does PA2 reflect the direction of the
> data lines? 

See the protocol description in the README file, I don't remember.  But
I think that someone should come up with something better.  EPP and ECP
printer ports are the standard on PCs nowadays, and I think it was
Wolfgang Moser who suggested that a more modern cable for prlink should be

Are there any hardware freaks out there who have enough free time?  Why
don't they approve these hobby projects as master's thesis titles? :-)  I
think that it would be great to construct a cable that works with C64,
VIC20, maybe the PETs, modern PCs and Amigas and makes use of the
automatic handshaking of the new-style PC printer ports.  I'm quite
satisfied with Frank Kontros' cable, but he asked me not to publish its
details.  I don't remember if it works with the PET, but I hacked it to
work with the VIC-20.  It is 4-bit to the PC side and 8-bit to the
Commodore side, and it buffers all signals and has semi-automatic
handshaking.  Hmm, maybe it could be possible to make a cable that looks
exactly the same to the C= side and makes use of the ECP/EPP features?
Any takers?

Meanwhile, you could use the 4-bit protocol and maybe modify it so that
one line (controlled by the Amiga, so that you don't need to change the
PET side program) reflects the data direction if it doesn't do it already.


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