IEEE once more.

From: Martijn van Buul (
Date: 2001-05-12 00:32:41


I decided to completely restart from scratch with my IEEE-to-IEC gateway;
things were starting to get rather complicated and spaghetti-styled. 
However, I'm not 101% sure that my KISS-solultion will work.

Basicly, I have three concerns:

1) Can I safely gateway ATN across IEEE and IEC? I mean: If a byte is
   transmitted under ATN over IEEE, does this mean that it has to be 
   (or can be) sent under ATN on the IEC bus as well (and vice versa?)

2) Re-reading old discussions, I stumbled across a comment by William
   Levak, claiming that untalk is used as a substitute for EOI on the
   serial bus. Somehow, I don't really understand this comment, unless
   my ideas about untalk and EOI are off. However, I browsed through
   the sources of Ruud's PCDISK, and they seem to correspond to my ideas.
   How can Untalk be a substitute for EOI? Consider a device transmitting
   data through the bus. If the controller wants the data stream to stop,
   it transmits UNTALK; if the transmitting device is out of data, it
   sends EOI. To me, these things are something entirely different, or
   am i wrong? Can a controller 'end' a transmission by asserting EOI
   as well, parallel to the talker?

   Related to this: What is the use of UNLISTEN? Isn't that exactly 
   the same as doing an EOI? 

3) Consider a serial talker, to an IEEE-listener. The talker happily 
   starts transmitting data, which I gateway to the IEEE bus. If, at a
   given time, the controller had enough, and asserts ATN, this will
   probably be in the middle of a byte being transfer on IEC. How should
   I handle this? In a 'best case scenario' :), this will result in the
   IEC talker 'talking' one byte too much.

I want to keep the thing as simple as possible, preferrably even stateless.

Any shed of light in these matters would be appreciated.

Regarding the discussion about the future of this list, I think that most
has already been said - I think I'll agree with Levente.

    Martijn van Buul - -
	 Geek code: G--  - Visit OuterSpace: 3333
   Kees J. Bot: The sum of CPU power and user brain power is a constant.
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