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The Georgia Tech Software Tools Subsystem and C Compiler for Prime Computers

This repo contains the source code and documentation for version 9.1 (the last version) of the Georgia Tech Software Tools Subsystem for Prime Computers and version 2.0 (also the last version) of the Georgia Tech C Compiler for Prime Computers.

This repo is primarily of historical interest, for those who worked on the subsystem, as well as for those who used it; there are no actual Prime computers still in use (to our knowledge), although emulators and emulated systems may be found on the Internet.

This README.md is still a work in progress. If you can fill in any of the missing information, please feel free to contact me!

Software Tools Subsystem History

The Software Tools Subsystem was developed and maintained for a long time by (in alphabetical order) Allen Aiken, Perry Flinn, and Dan Forsyth. Jack Waugh created the se screen editor. When the initial three developers left Georgia Tech, support then moved to Jeanette Myers, Terry Countryman, and Peter Wan. The final versions were developed and maintained by Scott (then known as Jeff) Lee and Arnold Robbins.

The final version of the subsystem was sent out to users in the fall of 1984, sometime around September or October of that year. At that point, the subsystem passed into history; we have no knowledge about how long it continued to be used by its licensees.

Some More History, Thanks to Dan Forsyth

Q. When did work first start?

I believe it was late fall of 1976. We were suffering withdrawal from the retirement of our beloved Burroughs B5500 and the dedication of our PDP-11/45 to a medical project.

Q. Did development start from the tools in the Software Tools book, or from the tools provided by the Software Tools User Group?

Absolutely from the book. There was no STUG at that point. Brian K. told us at one point later that we were the only people he knew of that had actually done all the exercises in the book.

Q. At what point did Georgia Tech start licensing and supporting the subsystem?

I’m going to guess about 1978 or 1979. I might be able to find this out.

Recovery History

While some of the documentation was saved (see the links, below), the subsystem code itself was believed lost for over 30 years.

Fortunately, in April of 2019, Scott Lee found two tapes he had made from the Georgia Tech Prime systems. One contained the subsystem, and the other contained the C compiler! These tapes were 35 years old, but had been kept in good condition, in a moisture-controlled environment.

With support from Arnold Robbins and Dennis Boone, the tapes were sent to a recovery service which was able to extract the contents with only one (!) damaged file. The non-binary contents of those tapes make up the content of this repository.

Installation Tape vs. Dump Tape

It appears that the Subsystem files are from a dump of one of the Georgia Tech Prime systems, and not from a formal installation tape as they were distributed to licensees. However, the C compiler files do appear to be from an installation tape.

Branches

The recovery branch contains all the files exactly as they were recovered from the magnetic tapes, including binary and executable files. Also available are .tap format files (tape images) for use with SIMH or other emulators.

The master branch contains the code and documentation in a format suitable for browsing on Unix-style systems. In particular:

  • All directory and file names are in lower case.
  • Line endings are LF, not CR-LF.
  • All binary files (executables, objects, anything noted as ``data'' by file(1)) have been removed.

The Software Tools Subsystem is underneath the swt directory, whereas the C compiler is under the c_tape directory.

C Compiler History

Paul Manno recounts:

Program Development Corporation was formed and I was one of the officers of the company. We did produce and sell a C compiler and library for the PR1ME Computers that operated under PR1MOS (their OS). Most realized we lacked enough corporate knowledge and there were no incubators that we knew enough about to fund us. So, after completing the sale of the C Compiler and run time libraries [to Georgia Tech], we agreed to close the company and seek our fortunes on a different path. The company was inclusive of Dan Forsyth, Win Strickland, Allen Akin, and a few others.

Dan Forsyth answers some questions:

Q. When did work on the C compiler start, and by whom? What years?

I think about 1980. I might have info on this that I can look up. PDC was Perry, Allen, Win Strickland, Paul, and me. I wrote most of the compiler front end and Allen wrote the back end (vcg) and used it as part of his master’s thesis.

Q. When did Georgia Tech buy back the C compiler?

I’m thinking this was late 1981 or early 1982.

Arnold Robbins thinks that Paul Manno wrote the first version of the C library. Arnold remembers working on it subsequently. For version 8.1 of the subsystem, the EOS character in the subsystem was changed from -2 to zero, for compatibility with the C compiler and library.

Arnold also recalls that Edward J. Hunt converted the vcg code generator to generate object code directly, instead of generating assembly code that had to be assembled with PMA (Prime's macro assembler). Ed used an object code generation library written by Scott Lee to do so. This basically doubled the compilation speed. Arnold thinks it was his suggestion to make this change, but he no longer remembers for sure.

Links Of Interest

Several bits of the Subsystem code were converted to C in the 1980s and are available separately. Of interest:

A Prime emulator is available on the Web. Here is the announcement. To access it, use telnet:

$ telnet em.prirun.com 8006

Different versions of Primos are available on ports 8001-8007.

Scott Lee's pdump program to extract Prime MAGSAV tapes on Unix is available here.

Dennis Boone has a number of Prime tools here.

Documentation Links

PDF files made by scanning some of the original documents are available on the Internet. Here are some links:

  • The Software Tools Subsystem User's Guide, 2nd edition is available here.
  • The Software Tools Subsystem User's Guide, 4th edition is available here.
  • The technical report on the reusable code generator used in the C compiler, Allen Aiken's MS thesis, is available here.
  • A (now) funny USENET article about C compilers and Unix for Prime computers is available here.

Dennis Boone has built PDFs of the User's Guide and the Reference Manual:

Last Modified

Fri Oct 4 14:34:43 IDT 2019

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