[vcf-midatlantic] 6502 assembly hack @ next workshop

[Evan Koblentz]

I've been spending a lot of time lately on learning more LOGO 
programming for the Lego/Apple II kit. It does some very cool things, 
but we need it to do something new. Read on...

Lego made a box that communicates between the computer and their motors, 
sensors, and lights. The box has eight ports. Ports 0-5 are for 
anything. Ports 6-7 are reserved for sensors.

You can talk to any port, but oddly you can only listen to ports 6-7. 
There is no way to tell LOGO, "What is the status of port 3?" All you 
can do for ports 0-7 is switch them on/off and adjust the voltage 
(SETPOWER command from 1 to 7 for full power).

Dean has been very helpful when I have programming questions. We tried 
working around the limitation by making a variable, setting it to 0 or 
1, and then checking the variable instead of the port when necessary. 
But it doesn't work (for various reasons; no need to explain them here.)

I had an idea. Why can't we hack Lego's version of LOGO to add this command?

Dean said it possible. Disassemble the code, identify where the ports 
are turned on/off, etc. .... the existing command to read ports 6-7 is 
LISTENTO (and also a short version LTO) so I propose a new command 
LISTENPORT or the short version LTP).

I will bring the setup to the January workshop and Dean (and Drew) are 
going to work on it. Anyone who digs Apple 6502 assembly is welcome to help.