Originally Posted by PaulyQ
I'll give it a try... I suppose I should really have looked at the memory map for the speccy first eh!
You'll find that the code posted is not going to do what the author intended :-p
Try this instead:
10 FOR f=USR "a" TO USR "a"+7: READ a: POKE f,a: NEXT f
20 DATA 255,129,129,129,129,129,129,255
Then enter graphics mode (Caps Shift+9 in an emulator, Alt-GR/Right-Alt in BASin) and press "a".
If you've not seen it, BASin is an Emulator/Development IDE for the best implementation of BASIC ever - Sinclair BASIC :-)
But that's really getting off-topic now.