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From: cs1598@athena.ecs.csus.edu (Michael Noriega)
Newsgroups: comp.sys.m68k
Subject: Re: HELP HELP HELP on some Technical Questions for the 680000!!!
Message-ID: <1991Apr10.093244.17409@csusac.csus.edu>
Date: 10 Apr 91 09:32:44 GMT
References: <1991Apr3.215104.21550@netcom.COM> <1991Apr4.105321.12087@csusac.csus.edu> <1991Apr9.165559.12876@motaus.sps.mot.com>
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In article <1991Apr9.165559.12876@motaus.sps.mot.com> skipper@motaus.sps.mot.com (Skipper Smith) writes:
>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.
> 

  Thanks for the correction Skipper.  I am starting to work on my Senior
Project for next semester and I planning on using the MC68000 and MC56001 so it
behoves me to know the 68000 inside and out.

>
>-- 
>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

        - Mike