Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!mit-eddie!bloom-beacon!eru!hagbard!sunic!mcsun!unido!alderan!bsteh@alderan.uucp
From: bsteh@alderan.uucp (Herbert Bsteh)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: How long to hold the IOCHRDY (IO Channel Ready) signal ?
Keywords: IOCHRDY, AT-BUS, ISA
Message-ID: <188@alderan.uucp>
Date: 2 Oct 90 01:22:24 GMT
Sender: bsteh@alderan.uucp
Organization: C. Splittgerber Datentechnik, Denkendorf, Germany
Lines: 16

According to various hardware reference manuals (Compaq, Intel)
we found different informations about how long we may hold the
IOCHRDY signal. Our Intel manual says something like :
"IOCHRDY must not be negated for longer than 15 us" - which does
make sense to me because of the REFRESH signal. Our Compaq manual
says "This signal should not be hold longer than 2.5 us ...".

For our application it is necessary, that the bus agent holds the
IOCHRDY for about 10-12 us.
Is there any good reason for restricting the "hold-time" to not longer
than 2.5 us.  and what problems could arise if we go up to the limit
of 15 us ?

Any help, hints or experiences are welcome.

Thanks in advance Herbert