Data General Nova - Emulating A Data General Nova

Emulating A Data General Nova

Nova assembly language programs can be run under Bob Supnik’s SIMH emulator, in RDOS. Of the above examples, only Hello, world is a complete program. It includes the necessary directives for a successful assembly and generation of a runnable program.

Stepwise instructions

Start the Nova emulation and boot RDOS following the instructions under “Nova and Eclipse RDOS” in the file src/simh_swre.txt of the simh distribution. After booting, RDOS’ command prompt, R, should appear on the screen.

• Before the first assembly on a newly setup RDOS system, the macro assembler’s default symbol definitions need to be configured using the following command: mac/s nbid osid nsid paru
• Create the assembly source file under RDOS: xfer/a $tti test.sr (the xfer command will accept input at the console and copy it to a disk file named test.sr; after entering the command, copy and paste (or type in) a complete assembly language program, and finish with control-Z).
• Next, run the macro assembler on test.sr to create the object file test.rb: mac/l test (the /l option enables the listing file test.ls, which can be copied to the console using the command type test.ls).
• The relocatable loader, rldr, takes the object file and creates the executable test.sv : rldr test
• To run the program, type test

Before going further with serious experimentation, it can be convenient to check one’s programs at the PC using a suitable cross-assembler, such as the portable PDP-8/DG Nova cross-assembler listed in the External links section, before attempting execution in the RDOS environment.

RDOS hints

• To have a directory listing of all files with basename test, type list test.- (note the hyphen, RDOS’ wildcard character)
• Delete files with delete (this might be needed because xfer won’t replace an existing file)
• A running program can usually be interrupted with Control-A
• To exit RDOS, type release %mdir%
• Quit simh at its prompt with q