Prime 50-series emulator online
Jim Wilcoxson
same design goals and aspirations of Multics, and many of the Prime
engineers were MIT alumni with Multics backgrounds. I'm not a member
of this group, but Paul Green suggested it would be appropriate to
post here about the Prime 50-series emulator I recently put online,
running on a Playstation 3 (PS3).
To access the emulator, telnet to prirun.dyndns.org port 8001, then
LOGIN GUEST, pw PR1ME (case doesn't matter). Once logged in, you can
use the HELP command to explore some of the Primos commands and get
more familiar with the environment. I believe Al Kossow also has some
scanned Prime manuals available online at bitsavers.org. You are
welcome to create a directory under the GUEST account for file space.
As a brief overview, the Prime architecture had 6 major machine modes:
16S, 32S, 32R, 64R, 64V, and 32I. All except 32I are supported in the
emulator. 32I support, and the extended variety, 32IX, are planned.
64R mode is a 64K-word (16-bit word) memory model, whereas 64V is a
segmented model with 8192 segments divided into 4 groups of 2048
each. The segment length on the Prime was 64K 16-bit words. The
first 2 groups of segments are common to each user's address space,
while the second 2 groups of segments are per-user. Typically, the
Primos Ring 0 code resided in the first group, shared system libraries
resided in the 2nd group, user application space was the 3rd group,
and per-user system data such as the command line was stored in the
4th group. Ring 0 and Ring 3 were implemented on the Prime.
64V mode is a 1-address architecture, with 2 16-bit index registers (X
and Y), a 16-bit accumulator (A), a 32-bit accumulator (L), a DP FP
accumulator, and 4 base registers. Using the special-purpose "field
address and length" registers, character mode instructions are
provided to copy, compare, translate, edit, and fill character string
fields, and also provide decimal arithmetic support for COBOL and PL/
I, including packed and unpacked decimal add, subtract, multiply,
divide, picture edit, move, and binary conversion. 64V mode has 16
commonly-used instructions that are a single 16-bit word, another set
of 32-bit wide instructions, and some 48-bit instructions for less
commonly-used features such as queue instructions (add to top or
bottom of queue, test queue length, remove from top or bottom of
queue) and loading the field address registers. It also had
hardware / microcode support for procedure calls with argument
transfer and process exchange (wait, notify, and process dispatching).
The version of Primos running on this emulator is 19.2, which is circa
1982. The emulator has most of the Prime languages loaded: FTN
(Fortran 66), F77, PL/I Subset G, Pascal, RPG II, BASICV, and CPL,
Prime's command language. EMACS and C were also available under this
revision, but unfortunately I don't have access to these for 19.2.
Prime also had a very sophisticated Source Level Debugger, DBG, but
this too is missing and not loaded. Primos 19.2 is written in a mix
of PMA (Prime's assembly language), Fortran 66 and PLP. PLP is the
special "systems programming" version of PL/I initially used at
Prime. Later versions of Primos migrated to SPL, a more extended
version of PLP. Both PLP and SPL are also loaded on the emulator. At
19.2, Prime was just starting to launch EPF's and BIND, which allowed
automatic page sharing of code pages and paging from the file system.
This was not officially supported for customers until rev 19.4 I
believe, so the EPF support is very minimal on the emulator. The
emulator has the ability to run Primos and Prime code unmodified. To
improve some aspects of usability, a handful of changes have been made
to Primos (for example, to support a fast system console). The
version of Primos running on the emulator was completely compiled and
loaded in the emulator environment. It's running about 1.4 MIPS on
the PS3 with no optimizations other than compiling with -O. On a high-
end Mac G5 the emulator runs around 2.7 MIPS, mostly because it is
very branchy and the PS3 does not support out-of-order execution as
well as the G4 and G5 PowerPC processors.
The emulator supports 128 connections, 8 disk controllers w/4 drives
each, 1 tape controller with 4 drives, a system console terminal,
system clock, and PNC Ringnet controller. The PNC emulation is not
yet complete, but eventually should allow multiple emulators to
communicate over the Internet as if they are on a ring. I have some
design ideas for allowing a single emulator to connection to multiple
rings - something that wasn't possible with the physical hardware.
The loopback Primenet code is functional, so for example, the Netlink
command can be used to do a loopback login (netlink -to em192a).
If you know someone who used to work with the Prime, they may enjoy
taking a spin on one again!
Thanks,
Jim
Jim Wilcoxson
> segmented model with 8192 segments divided into 4 groups of 2048
> each.
Correction: there are 4 groups of segments, with 1024 segments in each
group.
pri...@gmail.com
> To access the emulator, telnet to prirun.dyndns.org port 8001, then
> LOGIN GUEST, pw PR1ME (case doesn't matter). Once logged in, you can
> use the HELP command to explore some of the Primos commands and get
> more familiar with the environment. I believe Al Kossow also has some
> scanned Prime manuals available online at bitsavers.org. You are
> welcome to create a directory under the GUEST account for file space.
$ telnet em.prirun.com 8001
Trying 74.128.117.229...
Connected to em.prirun.com.
Escape character is '^]'.
Welcome to the Prime Computer 50-series emulator, running Primos rev 19.2!
Login as user guest, password pr1me
After logging in, use the Prime HELP command for assistance.
You are welcome to create a directory under GUEST for your files.
The line erase character is ?
There are other Primos revs running on ports 8001-8007
Prime manuals at: http://yagi.h-net.msu.edu/prime_manuals/prirun_scans
To report bugs or contact the author, send email to prirun a t gmail.com
Enjoy your time travels! -Jim Wilcoxson aka JIMMY
Login please.
Also, as an update from the original post, 32I mode is fully implemented and Prime Ringnet emulation over Unix TCP/IP is implemented. There are 7 emulators running, on ports 8001-8007, running Primos revs 18-24, and many of the emulators have remote disks added from other emulators (like NFS today).
Have fun!
Jim