PDP-11 SPACEWAR running again!

Curious Marc curiousmarc3 at gmail.com
Mon May 10 23:45:00 CDT 2021


> On May 10, 2021, at 11:26 AM, Mattis Lind via cctalk <cctalk at classiccmp.org> wrote:
> Today I finally got the SPACEWAR version for PDP-11/10 running again on my
> PDP-11/05 with AR11 board. I played a couple of rounds together with my
> daughter. She was better than me. Quite hard game IMHO.
> https://youtu.be/fTiHRAKjyho
> Bill Seiler and Larry Bryant wrote this version in 1974 and submitted it to
> DECUS. It was believed to have been lost to history. But Bill had saved the
> printouts from the PAL11 assembler. He sent me scans of these printouts as
> pdf files. I then transcribed it into source files and iterated several
> times in SimH to get a clean build and link. I got some help from people
> here doing OCR on some files. But the lines mostly confused the OCR process
> so a lot of errors was introduced. It turned out that it was easier to just
> transcribe the whole lot by hand than finding and correcting errors.
> The AR11 is somewhat different to the AD01 and AA11 that Bill and Larry
> used. AA11 has a 12 bit 2’s complement D/A while the AR11 is only 10 bits
> and not 2’s complement. I did some patches and eventually got everything
> right.
> I also connected a couple of analogue joysticks. The fire button is just
> short ciruiting the viper of the potentiometer to the 5V supply lead. The
> screen is a HP1332A vector screen.
> All the transcribed code, AR11 patches and build instructions are available
> on github. https://github.com/MattisLind/SPACEWAR
> It should be possible to adapt it to orher types of A/D and D/A hardware if
> anyone wishes to do so. However the gameplay might be harder when running
> on a faster PDP-11?
> Have fun!
> /Mattis

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