29 Oct
2010
29 Oct
'10
11:41 a.m.
On Fri, Oct 29, 2010 at 2:26 PM, Brent Hilpert <hilpert at cs.ubc.ca> wrote:
On 2010 Oct 29, at 10:39 AM, Ethan Dicks wrote:
I know it works well enough in early Sun workstations and the AT&T
Unix PC (3B1/7300), but I have no knowledge of any required
workarounds due to possible bugs.
That all depends. ?Back in the day, what we did was not demand-paged
virtual memory (something supported natively on the VAX and the 68010
(but not effectively on the 68000)... (which is part of what
distinguishes the 68010 from the 68000 - instruction restart).
There have been a couple of indications it was the '10 that added the
instruction restart, but was the implementation in the '10 bug-free? I didn't deal with the problem directly, heard
about it from some friends
who were programming around it, and it would have been 1989, so long after
the 00->10 transition. My recollection about the issue was there was a bug
under certain conditions that was fixed in the next version, as distinct
from a 'new feature', but perhaps it was just the way the problem was
described to me or the way I understood what was being said.
I have no memory of issues with instruction restart on the '10, but I
didn't use that feature of the chip when I was doing embedded product
development 20+ years ago (we only used it for the "loop mode"
1-instruction cache feature that allowed so-called "DBcc loops" to run
~50% faster due to not needing fetch cycles while in the loop).
Could what you remember be something to do with "instruction restart"
vs "instruction continuation"? (a distinction I was not making, but
now that I've read this -
http://www.easy68k.com/paulrsm/doc/dpbm68k1.htm - perhaps that's a
better way to describe it).
-ethan