17 Oct
2011
17 Oct
'11
3:18 p.m.
From: Toby Thain
Sent: Sunday, October 16, 2011 11:18 AM
On 16/10/11 1:54 PM, Chuck Guzis wrote:
> What can be done with a really good
macro-assembler is very eye-
> opening.
Indeed. You're probably familiar with the epic
hacks that make, e.g.
MACRO-11 assemble for a completely different instruction set :) (A
gentleman named Tom Evans showed me this.)
The 8080 simulator used by a certain trio[1] of programmers to write an
interpreter for BASIC used PDP-10 macros that converted 8080 assembler
code to PDP-10 LUUOs[2] with the 8-bit values for the 8080 in the high-
order 8 bits. The simulator was written by the eldest of the three,
based on one he had written a few years earlier for the 8008.
I've seen the code. Hell, I've run the code. It's awe inspiring.
[1] A lot of people forget who did the math routines...
[2] Original PDP-6/10 operating systems use illegal instruction traps as
system calls. These UnUsed Operations (later, Unimplemented User
Operations) are divided into Monitor and Local UUOs. Instructions
040-077 are monitor calls, 001-037 use the same mechanism in user
address space. Clever programmers use this as a fast subroutine call
mechanism.
Rich Alderson
Vintage Computing Sr. Server Engineer
Vulcan, Inc.
505 5th Avenue S, Suite 900
Seattle, WA 98104
mailto:RichA at vulcan.com
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/