Could Sinclair’s 48k Sinclair ZX Spectrum land a spacecraft on the Moon? YouTuber Scott Manley decided to find out, and the answer is… kind of.
Phrases along the lines of “they landed on the Moon with less computer power than what’s on your wrist / in your phone / ” became commonplace over the decades and, while it is true the raw computing power is of an order of magnitude greater than what was available during the Apollo era, there is also truth in the statement “it isn’t what you’ve got, it’s what you do with it.”
Enter YouTuber Scott Manley and a project to land a spacecraft on the Moon, with a ZX Spectrum being used to control the descent to the surface.
Naturally, Manley didn’t have a real spacecraft and had to make do with the Kerbal Space Program, a spaceflight simulation game. He also used an emulator for the ZX Spectrum and Interface 1, and Python to glue the systems together.
Why the Interface 1? Manley used a virtual serial connection to shuffle data around. In addition to a Microdrive controller, the Sinclair Interface 1 featured an RS-232 interface. Although the serial interface could – in theory – rock along considerably faster, Manley stuck with 9.6 kbit/s, which turned out to be perfectly adequate for his purposes – getting a Sinclair BASIC program to respond to and direct the thruster firings in the Kerbal Space Program simulator.
Manley acknowledged that going down the Z80 machine code route would have been quicker, but sticking with BASIC makes the code more immediately accessible.
Did it work? Kind of. After a bit of tinkering to ensure the BASIC code and the Kerbal simulation remained synchronized and that communication lags didn’t reach a point where the spacecraft slammed into the virtual lunar surface, Manley’s lunar lander… landed.
However, the engineer acknowledged that there were plenty of limitations. “It has no guidance,” he said, “It barely has attitude control.”
Yes, Scott, but it did manage a landing. Using an emulated 48k Sinclair ZX Spectrum. It is a ridiculous enterprise, but at the same time, really rather excellent.
Rumors that NASA intends to pack an old Speccy as a backup on the Artemis IV mission are, of course, entirely false. Not least because the Blu-Tack often used to stop the power cable falling out is unlikely to pass space qualification. ®