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Elite on the BBC Micro

Tube: tube_elite [Elite-A, I/O processor]

Name: tube_elite [Show more] Type: Subroutine Category: Tube Summary: Set the vectors to receive Tube communications, run the parasite code, and terminate the I/O processor's loading process
Context: See this subroutine in context in the source code References: No direct references to this subroutine in this source file
.tube_elite LDX #&FF \ Set the stack pointer to &01FF, which is the standard TXS \ location for the 6502 stack, so this instruction \ effectively resets the stack LDA #LO(tube_wrch) \ Set WRCHV to point to the tube_wrch routine, so when STA WRCHV \ bytes are sent to the I/O processor from the parasite, LDA #HI(tube_wrch) \ the tube_wrch routine is called to handle them STA WRCHV+1 LDA #LO(tube_brk) \ Set BRKV to point to the tube_brk routine (i.e. to the STA BRKV \ Tube host code's break handler) LDA #HI(tube_brk) STA BRKV+1 LDX #LO(tube_run) \ Set (Y X) to point to tube_run ("R.2.T") LDY #HI(tube_run) JMP OSCLI \ Call OSCLI to run the OS command in tube_run, which \ *RUNs the parasite code in the 2.T file before \ returning from the subroutine using a tail call \ This terminates the I/O processor code, leaving the \ BBC Micro to sit idle until a command arrives from the \ parasite and calls tube_wrch via WRCHV