Date: Sat, 8 Jan 94 17:06:45 EST
From: peprbv AT cfa0 DOT harvard DOT edu (Bob Babcock)
To: stevev AT miser DOT uoregon DOT edu
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: What is the address of the code?
Reply-To: babcock AT cfa DOT harvard DOT edu

> Offhand I do not know if the 486 has a prefetch queue in addition to its
> internal cache; it seems that the cache would make a prefetch queue
> unnecessary, though.

The 486 does have a prefetch queue.  It seems to be 32 bytes deep.  This broke
some versions of the DIET file compressor which had self-modifying code which
patched in a jump address exactly 32 bytes away from the patching code.  Only
some compressed programs failed, and single stepping with a debugger made them
work.  (The program which I use to duplicate shareware disks for my customers
was the one which broke.  It took a long time to figure out why.)