From: Greg King (gngking_at_erols.com)
Date: 2003-06-10 12:40:40
-----Original Message-----
From: Baltissen, R (Ruud)
Date: Saturday, June 07, 2003, 03:13 AM
>
> Hallo Marko,
>
> > I remember seeing a piece of code that tells a printer to
> > LISTEN and a disk drive to TALK, in order to print a file
> > while the computer could do something else.
>
> Quite simple if two drives are concerned:
> -- you tell the TALKER what file to send
> -- you tell the LISTENER what file to receive
> -- you tell the LISTENER to start to LISTEN
> -- you tell the TALKER to start to talk
A fifth step is needed:
-- you "disconnect" from the bus.
The General Purpose Instrument Bus allows multiple controllers. They (and
other devices) have three modes: listen, talk, and idle. But, Commodore's
version allows only one controller (the computer); it never idles! That
program "fakes" the idle-mode. It sets the IEC's output-buffers so that
they let the lines float (high). That step stops the computer from
interfering with the transfer between those devices.
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