From: Spiro Trikaliotis (ml-cbmhackers_at_trikaliotis.net)
Date: 2004-09-09 09:03:39
Hello Ruud,
I mail you directly besides the ML, as the mailing list seems to have
severy problems again.
* On Thu, Sep 09, 2004 at 07:46:50AM +0200 Baltissen, GJPAA (Ruud) wrote:
> What tells $FFD2 to send the last byte with an acive EOI ????
If you look at the IEC code (I did so in the C64 kernal), you see that
each byte is not send immediately, but it is send delayed.
What do I mean:
1. You call with the first byte: Nothing is seen on the serial bus, but
the character is buffered only.
2. You call with the second byte: The first byte is send on the serial
bus, and the 2nd byte is buffered.
3. You call with the 3rd byte: The 2nd byte is send, and the 3rd is
buffered.
Now, if you issue a UNTALK, UNLISTEN, TALK or LISTEN, before this
happens, the last byte in the buffer is send out on the IEC bus, with
set EOI.
If you like, I can look up the disassembly areas where this happens.
Anyway, I think I lately posted this on this list in a reply to Jim
Brain: On Mon, 21 Jun 2004 18:49:20 +0200, I told how I modified the
C64's KERNAL to not send the EOI.
HTH,
Spiro.
--
Spiro R. Trikaliotis
http://www.trikaliotis.net/
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