Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!oakhill!motaus!skipper
From: skipper@motaus.sps.mot.com (Skipper Smith)
Newsgroups: comp.sys.m68k
Subject: Re: HELP HELP HELP on some Technical Questions for the 680000!!!
Message-ID: <1991Apr9.165559.12876@motaus.sps.mot.com>
Date: 9 Apr 91 16:55:59 GMT
References: <1991Apr2.220648.23079@colorado.edu> <1991Apr3.215104.21550@netcom.COM> <1991Apr4.105321.12087@csusac.csus.edu>
Organization: Motorola Semiconductor, Austin, Texas
Lines: 18

In article <1991Apr4.105321.12087@csusac.csus.edu> cs1598@athena.ecs.csus.edu writes:
>  VPA*, VMA*, and E* are all used in synchronous communication.  When
>the 68000 looks for DTACK* and does not receive it, it checks for VPA*.
>If VPA* is asserted then it now knows it is talking to a sychronous
>device.  VMA* and E* are then used in communicating to the device.
>
>      - Mike

Technicality time:  Actually, /VPA (or VPA* depending on your teacher) is    
checked prior to /DTACK.  If they are asserted at the same time, /VPA will be
used.  However, somewhat obviously I hope, they should never be asserted at the
same time.  Everything else you said was not only correct, but said quite well.
 

-- 
Skipper Smith                             | skipper@motaus.sps.mot.com
Motorola Technical Training               | 8945 Guilford Rd  Ste 145  
All opinions are my own, not my employers | Columbia, MD 21046