Dave Pitts is making progress running Fortran II

I have been negligent in reporting impressive progress made by Dave Pitts emulating IBM 7090 software. As Leif Harcke posted to alt.folklore.computers and bit.listserv.ibm-main on 2 February 2005:

Dave has developed his “asm7090” cross-assembler to the point where it can assemble the core of IBSYS from MAP source. The resultant IBSYS image will run the Fortran II(?) compiler on a modified version of Paul Pierce’s “s709” 700/7000 series emulator. The object code produced by the Fortran compiler does not run under IBSYS, however.

The cross-assembler and emulator are written in C, and build under Linux. Presumably they are easy to port to other POSIX-compliant systems. Details on the project are available here:


If anyone is interested in helping out, Dave could use a hand debugging the emulation and getting IBSYS and other related system tools working.

Today, Dave told me:

With the current version of the emulator, 2.0.4, I’ve been able to run the following:

1. FORTRAN IV – Compile and run both Primes and Laplace programs.
2. COBOL – Compile and run the hello world program.
3. FORTRN II – Compile the Primes program. The exec doesn’t work, I get a checksum error loading the runtime (bad tape??).
4. MAP assembler – I’ve only run the assembler, didn’t try to run output.
5. FAP assembler – I’ve only run the assembler, didn’t try to run output.

My current IBSYS tape has the nucleus assembled with my ASM7090 cross assembler. Also, I re-assembled the COBOL compiler with ASM7090 and put on the tape.

I know that Leif Harcke has been hacking on the FORTRAN II. I think he’s stuck at the same point as I am. I’ve been trying to get the FORTRAN II parts to assemble with ASM7090 to replace the tape image with a NOPed checksum test.

Update 2016/12/25: Updated URL for Dave Pitts.

Update 2016/1/2/: Updated URL for Leif Harcke and links to Usenet groups.

Update 2024/05/08: Updated URL for Leif Harcke via Internet Archive Wayback Machine.

2 thoughts on “Dave Pitts is making progress running Fortran II”

  1. I have just written a program in FORTRAN IV in order to solve an interesting math problem which was given to me by a fellow employee.

    But I have not the slightest idea how I can run the program. Any ideas?

    It is about thirty lines log.

    I have a few old Radio Shack Computers in my cellar and will get them out to see if I might run the program on them.

  2. Bob,

    The best answer is probably to install GNU Fortran, and use its g77 compiler, which can handle Fortran IV as well as Fortran 77 source programs. GNU Fortran is part of the GNU Compiler Collection, including C, C++, and various other languages. One way to install it on a Windows PC is as part of the free Cygwin package (see http://www.cygwin.com/). According to this page, g77 is no longer being maintained with the newest versions of the GNU Compiler Collection, so you may need to do some looking to find an older version: http://gcc.gnu.org/wiki/GFortranG77 .


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