This is a software emulator for a minicomputer architecture sold by Prime Computer from the early 70s through about 1993. Prime's initial business plan was to make systems compatible with the Honeywell x16 family, which had then-recently been discontinued. Prime extended the architecture heavily.

Emulator History

Beginning in 2005, Jim Wilcoxson developed an emulator for Prime Computer's 50-Series architecture. The emulator originally ran on the PowerPC architecture. In late 2011, Jim ported it so it would run on x86. This entailed solving endianness issues (The 50-Series is big-endian), as well as re-optimizing the code for performance without the host processor having a large set of general-purpose registers.

Emulator Documentation

Coming soon, we swear!

Public Systems

There are a set of emulators available for public use. These may be accessed via telnet to the appropriate port on em.prirun.com.

PRIMOS Revision	Port
18.3.1	8007
19.2	8001
20.2.8	8002
21.0.6	8003
22.1.4	8004
23.4.Y2K.R1	8005
24.0.0.r15	8006

For example, telnet em.prirun.com 8001.

Prime History

Some information about the Prime company is available in the FAQ which was assembled by denizens of the comp.sys.prime usenet group and Info-Prime mailing list around the time Prime's 50-Series business unit ceased to exist. A reformatted copy is available here.

Prime Documentation

A growing collection of Prime and related documentation is available at sysovl.info. A howto on installing PRIMOS in the emulator is here. Discussion of adapting these instructions to 22.1.4 has been occurring on the cctalk mailing list.

Getting PRIMOS

Two versions of PRIMOS are available from Bitsavers:

Rev 22.1.4 [has issues]
Rev 22.1.4 repacked [use this]
Rev 19.?

The Rev. 19 tape is a save from an installed system.

Sample System Images

A set of sample system images derived from the public emulators can be downloaded to get you started. The tarball is 143510751 bytes, and its sha256sum is f7bf880cb1c7f32903ad85c4f52386cf2179067b8bfcf2c10b51c2e4dcf074dd. (gzip compression would only reduce this by ~400 kilobytes.) V4 corrects ACL problems in the Rev19 and Rev24 images.

V3 removes additional junk, and rebuilds the disk images as 600 MB drives, split 30/10 heads filesystem/paging. This tarball preserves sparse allocation ("holes"), so that uninitialized space in the disk images does not occupy actual space. You may need to tell tar to preserve this sparse allocation when you extract, e.g. with the -S option. Also includes enhancements to the wrapper scripts: directory independence and the ability to run the runem script from a terminal.