If you’ve read Frank O’Brien’s wonderful book The Apollo Guidance Computer: Architecture and Operation, and you are hungry for more, or just curious to see what using the DSKY was like, there are many options. If you’re a a programmer, and want to dive into the guts, you can find almost everything imaginable — including the complete AGC source code — at Ron Burkey’s Virtual AGC site.
One quick explanatory note: emulations mimic the hardware, running the original AGC software; this is resource-intensive so may not work well on resource-limited devices (like phones). Simulations mimic the functionality of the software, so work well on limited-resource devices, but may not provide operational fidelity.
https://www.ibiblio.org/apollo/
Ron Burkey started this site as a place to share his amazing open-source emulation of the AGC. Over time it has become the ultimate repository for everything concerning the AGC — and has expanded to cover the Saturn Launch Vehicle Digital Computer (LVDC), the Gemini On-Board Computer (OBC), and most recently the Shuttle AP-101 computer. Ron’s yaAGC/yaDSKY is a complete and comprehensive emulation of the AGC and DSKY. This emulation actually runs the original AGC software. This is the sine qua non of AGC simulation/emulation/documentation. yaAGC/yaDSKY needs to be installed; they run on Windows/MacOS/Linux. Advantages: this is the benchmark for AGC simulations/emulations, since it runs the original software. Drawbacks: just like the real thing, this depends on additional hardware to be “useful”, and there isn’t any for this emulation. Bonus: Ron Burkey maintains the mother lode of AGC documentation on this site. Even if you don’t install yaAGC/yaDSKY (and why wouldn’t you??), you need to keep a bookmark to his site just for the documentation library he maintains.
https://www.ibiblio.org/apollo/Pultorak.html
A few people, including John Pultorak and Mike Stewart, have recreated physical versions of the AGC. Interesting, fascinating even (especially Mike Stewart’s FPGA version) — but unless you are a real hardware wizard, you can’t play with these. Still, you can admire the dedication and ingenuity.
https://www.ibiblio.org/apollo/Restoration.html
https://www.curiousmarc.com/space/apollo-guidance-computer
This is a restoration and revivification of an actual, real AGC — the one that was installed in LTA-8. You’ll never get to interact with it, but Marc Verdiell has documented the restoration in exquisite detail, and you’ll learn a lot. This is a rabbit hole you will not want to emerge from.
https://svtsim.com/moonjs/agc.html
Moonjs is an online AGC simulator. It is a port of Ron Burkey’s Virtual AGC from C to javascript/asm.js using the Emscripten compiler. It includes a simplfied “eight-ball” and imagined navigational outputs. This is a web app, so just go to the site. This implementation adds some simulated scenarios like launch, but the scenario implementations are not remotely realistic.
https://michaelfranzl.github.io/webAGC/demo/
https://github.com/michaelfranzl/webDSKY
https://github.com/michaelfranzl/webAGC
Basically runs yaAGC/yaDSKY in a browser. Awesome! No install needed. All the advantages and drawbacks of yaAGC, plus, by default all the I/O channels and erasable memory locations are monitored — sweet! WebAGC doesn't pretend to do anything yaAGC doesn’t, so this is more reasonable than MOONJS.
https://idsky.genedorr.com/iDSKY.html
https://github.com/ehdorrii/idsky
This is my own version of a DSKY/AGC simulation. It’s a web app, so you only need to point your browser to this page. Despite being a mere simulation, it does a high fidelity job on the basic verbs. It also lets you do a couple interesting scenarios — launch and TLI. The simulations of these scenarios are based on the “cue cards” provided to the crews for monitoring displayed values, so the numbers you’ll see are quite close to what the crews saw in flight. iDSKY works on any platform with a reasonably recent browser: Windows, MacOS, Linux, iPad, iPhone, Android, etc., etc.
https://itunes.apple.com/us/app/dsky/id567387896?mt=8
This iPad app is a simulation of the AGC/DSKY. If you know little or nothing about the AGC/DSKY, it is educational; but if you are somewhat knowledgable, it falls short in accuracy and realism. This simulation incorporates input from standard iPad sensors, which is fun, but entirely unrealistic. Works only on an iPad, not on iPhones.
http://www.cems.uwe.ac.uk/~jtwebb/agc/agc_simulator.htm (dead link)
https://www.slideserve.com/clara/simulation-of-apollo-guidance-computer-powerpoint-ppt-presentation
Julian Webb wrote an AGC emulation completely independent of Ron Burkey. It seems to have disappeared from the Inrernet — I used to have a copy, but it’s gone now, a victim of PC replacement syndrome. It wasn’t as pretty as yaAGC/yaDSKY, and it wasn’t open source, but it worked well. It also had virtually no documentation. Like yaAGC/yaDSKY it needed to be installed; but it ran on Windows only. Pretty much the same advantages and drawbacks as yaAGC/yaDSKY, for the same reasons.