Re: C64 IEEE interface

From: Michał Pleban <>
Date: Fri, 07 Nov 2014 15:07:21 +0100
Message-ID: <>

Michał Pleban wrote:

> Bad news: the timeout/device not present error is not returned reliably
> from the IEEE routines at all. In fact, you will only get it in some
> very specific conditions, most likely when you instruct the device to
> TALK and it does not talk. The error is _not_ returned at all when you
> order it to LISTEN and it does not listen. So basically there is no
> simple method of determinig whether a device exists or not.

OK one more thing I remembered. This strange behavior exhibits itself
only when there are no devices on the IEEE bus at all.

So if you have #8 on the bus, reading from #9 will give an error.

But if there is nothing on the bus, reading from #8, #9 etc will not
give an error, at least not in the early stages of the communication.

So maybe there could be another check for some bogus device like #29. If
contacting this device does not return an error, that would mean that in
fact _nothing_ is on the IEEE bus. Thus the detection routines could
possibly be enhanced by this.


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Received on 2014-11-07 15:00:03

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