Re: C64 IEEE interface

Date: Sat, 08 Nov 2014 10:37:58 +0100
Message-ID: <>
Hallo Michał,

> Bad news: .....

I have read it and my first impression is that you do something 
wrong. To make sur I have to read it again. 

The protocol of detecting the present of any drive is simple: make 
ATN (L) and NDAC and NRFD should become (L) as well. If they don't, 
no IEEE device is present.

If a device is present, send device number. All devices not having 
this number, will release NDAC and NRFD. So if both NRFD and NDAC 
become (H), the wanted device is not present. Only after the device 
has shown its present, you start with TALK, LISTEN or what ever. 

IMHO the whole operation takes less then 100 cycles.

Kind regards / Met vriendelijke groet, Ruud Baltissen

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Received on 2014-11-08 10:00:03

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