That's what it was! As a kid I had the TRS-80 Coco, related to the Sinclair, and I remember one of those graphing programs you typed in from Rainbow magazine,

That's what it was! As a kid I had the TRS-80 Coco, related to the Sinclair, and I remember one of those graphing programs you typed in from Rainbow magazine, and I think it was able to plot the equation you had in a REM statement, that also had to be on a particular line number. There was a statement at the top of the program, like what you have here (maybe a POKE?), and I always knew it did something magical to be able execute from a REM statement, but I could never put it together. The Star Trader game was also really ahead of its time. There was no Google, and I've forgotten about it until just now. But, that makes sense. Thanks.