Hi Peter.

I went back and looked at the original copy I downloaded and its does have the "MOV P0,#0FFh" commands in it.
It also has P1,P2 and P3.

Regardless, I finally got it to work.
I didn't take the time to look through all of your initialization of TCON TMOD and SCON, but I went and got a copy of the same setups from some example programs I got with my eval board.
Once I fixed the typos I posted about (I'm using ASEM-51 assembler), I finally got there.

I even added my own test command definition and it worked first shot. Don't really understand the nuts and bolts of how/why it worked but it did.

I'm curious about getting a parameter with the command next.
And having a larger command buffer, the information I may ultimately send could have upwards of 64 bytes.
I saw somewhere in somebody elses examples of placing a buffer in the DSEG? Sound right? and they used a full 255 bytes, that'd be nice, but in reality, for my needs, I probably only need 64 bytes X 2, plus 4 X 1 bytes for numbers that will never exceed 255.

Thanks for having already created the basics.