New Version of Apout PDP-11 Emulator

Warren Toomey wkt at
Tue Jan 4 08:58:41 AEST 2000

Welcome back to all the PUPS mailing list members! They've finally turned our
router back on here, so now the list server Minnie is no longer deaf.

Over the past few weeks I've been working on my Apout simulator, with help
from Tim Shoppa, and it now runs binaries from 1st Edition UNIX. The
announcement is below; details of how to obtain the source, and some UNIX
binaries, are also given.

Hope you all had a good festive break, and best wishes for the New Year.


               Apout -- Simulate PDP-11 Unix a.out binaries
                            Version 2.3 Alpha

                     Warren Toomey  wkt at
                               January 2000

This program is a user-level simulator for UNIX a.out binaries. Binaries
for V1, V5, V6, V7, 2.9BSD and 2.11BSD can be run with this simulator. The
user-mode PDP-11 instructions are simulated, and TRAP instructions are
emulated by calling equivalent native-mode system calls.

The advantages of an a.out simulator over a full-blown PDP-11 simulator are:

   + system calls can be done natively, thus speeding up execution
   + the simulator is less of a CPU-hog than a full-blown PDP-11 simulator
   + you don't need a simulated operating system or a simulated file system

Apout can be obtained via anonymous ftp at in the
directory pub/PDP-11/Sims/Apout. The directory pub/PDP-11/Sims/Apout/UnixBins
contains tar archives of a.out binaries from several versions of UNIX.

The program is now at release 2.3 Alpha1. Most of the binaries from V5, V6
and V7 run fine. All of the V5/V6/V7 system calls are caught, but some are
ignored and some generate EPERM errors. The V1, 2.9BSD and 2.11BSD
environments are still under construction: see the file LIMITATIONS for
details. Finally, the simulator won't run on a big-endian machine.

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