I think its fair to say computers this simple couldn't really be sabotaged. You'd just power cycle them and they'd be back to the basic prompt (I dunno if this computer needed basic run from disk or it booted into it like a TRS-80). This is just like writing 10 Print "Microsoft!" and 20 Goto 10. I imagine in both cases pressing the break key, or similar, is all you need to end this loop anyway.

If the computer was just sitting at the basic prompt it wasn't doing anything anyway.