As far as cool things go, this one is pretty much near the top. Sure, I have no idea what I’d ever do with a KDF9 emulator, but the fact that someone has gone to the trouble of actually making one and have done so using Ada 2005, is just amazing, or as Georg Bauhaus says:
To see a computer of roughly my own age having used highlighting,
in color, making form follow function, and serving intuition
(“it’s that simple”…) is amazing. I apologize if this is its least noteworthy feature. It is spectacular. It’s got separate stacks for separate purposes! Another of the few insights into the history of wonderful inventions that market forces have not improved.
An emulator is being written with the ultimate objective of being able to run KDF9 object programs under the control of an original operating system. It is also intended as lasting and accessible documentation of the KDF9 architecture. ee9 is a substantial program: more than 20K lines of source code in Ada 2005, and still not complete. The touchstone of its success has been to run the Whetstone Benchmark on its original platform: the Whetstone Algol programming system for the KDF9. According to the emulators virtual CPU time, the run took 423 seconds; Brian Wichmann measured 417 seconds on an actual KDF9 in 1972. The real CPU time used by the emulator on my MacBook Pro was just 1.6 seconds, so ee9 is more than 250 times faster than the original KDF9 hardware.
There’s a lot more information to be found in the ee9 manual (PDF), which by the way is excellently written.
You can read the full release announcement here.