PiDP8 – still fun after all these days…

I’m still having a blast with my PiDP8, which is a PDP8/I replica that uses a Raspberry Pi (3 in my case) to provide PDP8/I emulation inside a very nice box with replica PDP8/I switches and blinking leds. The PiDP8 was created by Oscar Vermeulen in the  Netherlands and is available from him as a kit. If you are interested, his website is!pidp-8/cbie

I’ve attached a picture of my finished kit to this post as well.  I’m very happy with the build and with the overall unit. I only had one build problem – There’s a 40-pin header for the Raspberry Pi, and I always solder things in alternate pins/rows to spread the soldering heat evenly about the build. In this case, I managed totally miss one connection. Of course it was the main power connection between Pi and PiDP8, so when I finished, checked & double checked and finally connected it all up and applied power… nothing. After a careful re-scanning under a large magnifier knowing it had to be something really simple, I found the bare connection. Once soldered everything worked perfectly.

As I’ve said in other posts, I’ve been having a blast resurrecting my Engineering graduate studies FORTRAN programs and getting them to run on the PiDP8. I now have over 30 programs running, and all but a couple give results comparable to the same programs’s original output  and my modern 64-bit PC tests. In those cases, it’s due to single-precision floating point rounding errors that cannot be avoided. The originals were double precision, but the PDP8/I FORTRAN IV compiler does not support double precision. Still, I am satisfied with my results, and it was a lot of fun to do.

T800_PiDP8 completed 2016-05-26

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