A bit frustrating for someone who doesn’t know Manic Miner so I didn’t know which system this was written for or anything about the game. I hate it when stuff like this gets linked and there’s no broader context to the page.
At this stage, if you don’t already know which system Manic Miner runs on, then you don’t need to read the disassembly. For some of us it’s almost genetically encoded information.
And yeah, Google.
Type "Manic Miner" into your browsers search bar?