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From: frankr@enmasse.UUCP (Franklin Reynolds)
Newsgroups: net.micro.68k
Subject: Re: Latest MC68020 bug list by request
Message-ID: <454@enmasse.UUCP>
Date: Wed, 21-Aug-85 16:17:10 EDT
Article-I.D.: enmasse.454
Posted: Wed Aug 21 16:17:10 1985
Date-Received: Sat, 24-Aug-85 17:17:31 EDT
References: <483@oakhill.UUCP>
Reply-To: frankr@enmasse.UUCP (Franklin Reynolds)
Organization: Enmasse Computer Corp., Acton, Mass.
Lines: 43

In article <483@oakhill.UUCP> davet@oakhill.UUCP (Dave Trissel) writes:
>The allegations are quite absurd. Here is the latest bug list for the '020
>1A45J mask which has been out for some time. This is as of August 12, 1985.
>
>  1) the CAS2.x instruction will not operate correctly if either of the
>     operand effective addresses is data register indirect (Dn).
>
>  2) The TAS instruction will not operate properly if either the read or write
>     portion of the RMC cycle is bus-errored.  (We have a ten line fix for
>     this in the exception handler.)
>
>  3) The BTST (bit test) instruction when used as follows will not do the bit
>     test:
>			 BTST    Dn,#<  >

I just checked the letter I received from Motorola describing bugs in their
A45J mask. Please note that my letter is dated july, not august, 1985.
Anyway, the first two errors are listed but the third is nowhere to be found.
In addition, six other bugs are listed. 

1. LINK A7,Disp will load A7 with an undetermined value.

2. During power on RESET the RMC pin may be driven high. If bus error occurs
during an arbitrated bus cycle, RMC may driven high for several clocks
before being tri-stated.

3. Coprocessor primitive to evaluate EA and transfer data where the EA is
immediat addressing and the size is byte passes the operand to the co-
processor as a word. As such, the byte operand is passed in bit position
[23 -16] rather that bit [31-24].

4. CMP.x (A7)+,(Ax)+ may not work correctly in a virtual environment.

5. There is  a problem with the RTE instruction when returning from a bus
access error (bus error or address error) that may cause the porcessor to
hang up.

The letter goes on to describe how to write a bus exception handler that 
can deal with problem mentioned above.

Franklin Reynolds
EnMasse Computer Corp.
{genrad,panda,harvard}!enmasse!frankr