With the basic system, you don't need anything more than a palmpilot with a terminal emulator to write and test code. I ain't ever seen a virus on a palmpilot....

10 PRINT "Mtop ",MTOP

Is a good start. It tells you how much RAM the system thinks it can see. It should be the same as you think you have, but it often isn't. Its a simple test of your memory mapping logic.

You can toggle processor bits directly, but I cannot for the life of me remember the command.

You could have done with mapping a pack of LEDs onto a memory location and then you can get pretty light chaser effects to play with.

Steve