pdp11 BBC BASIC for the DEC PDP-11
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I started BBC BASIC for the PDP-11 at university on the late 1980s. It got as far as starting up, producing its startup message and prompting for input. A few years ago I wrote a PDP emulator and assembler, so I am working on completing it. I have been testing it on UNIX Version 6 and UNIX Version 7 running on the SIMH PDP-11 and Ersatz-11 emulators as well as PDPTube.

BBC BASIC uses standard PDP-11 UNIX TRAPs for I/O (eg TRAP 4 for character output and TRAP 3 for character input), so should run on any compliant PDP-11 UNIX. With a suitable HostIO source BBC BASIC should run on other PDP-11 systems, eg on RSX-11. For example, TubeIO uses PDP Tube EMT calls for I/O and BBC BASIC will run on a PDP-11 second processor connected to a BBC or Master.


  • Download bbcbasic (15K, v0.21, 29-Aug-2015).
  • Copy the file to an appropriate directory or into a Unix disk image with a tool such as UxFiler. On Unix a suitable location would be /usr/bin.
  • With PDPTube on RISC OS, Windows or UNIX, type bbcbasic at the PDP> prompt. PDPTube implements the full BBC graphics interface and can also run basic.rom which is optimised to run on a PDP-11 Tube CoProcessor.
  • With a real PDP-11 system, or an emulator that boots into Unix, log on and type bbcbasic at the user prompt.
  • With a PDP-11 Tube CoProcessor basic.rom can be put in a sideways ROM/RAM bank and entered with Ctrl-Break or *BASIC.

    Install shows more detailed examples on running PDP-11 BBC BASIC. You can also see blog entries following PDP-11 BASIC's development.

    Title Version Files Size Description
    BBCBasic 0.21
    Latest version of PDP-11 BBC BASIC.
    Author: J.G.Harston.
    blog       Blog following the development of PDP-11 BASIC.

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