Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!gatech!uflorida!novavax!hcx1!hcx2!daver
From: daver@hcx2.SSD.HARRIS.COM
Newsgroups: comp.arch
Subject: Re: Execute instructions
Message-ID: <93900012@hcx2>
Date: 22 Jul 88 16:54:00 GMT
References: <787@amethyst.ma.arizona.edu>
Lines: 15
Nf-ID: #R:amethyst.ma.arizona.edu:787:hcx2:93900012:000:596
Nf-From: hcx2.SSD.HARRIS.COM!daver    Jul 22 12:54:00 1988


>   What other machines have this type feature, and do people use it anymore? 

The Harris H-series has an EXM instruction, whose operand is the address of the
instruction to be executed.  (And if the instruction to be executed is a two-
word instruction, the second word must be placed after the EXM instruction!)

Examples of its usage include:
1) Dynamically modifying the count to a shift instruction and EXM'ing the
   shift.
2) Selecting which subroutine to call, placing the call instruction in a 
   memory word, and then EXM'ing the subroutine.
3) Lots more.

Assembly code is neat. :-)