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Elite on the BBC Micro and NES

Drawing the screen: sync_in

[Elite-A, I/O processor]

Name: sync_in [Show more] Type: Subroutine Category: Drawing the screen Summary: Implement the sync_in command (wait for the vertical sync)
Context: See this subroutine in context in the source code References: This subroutine is called as follows: * tube_table calls sync_in

This routine is run when the parasite sends a sync_in command. It waits for the next vertical sync and returns a value to the parasite so it can wait until the sync occurs. The value returned to the parasite isn't important, as it's just about the timing of the response.
.sync_in JSR WSCAN \ Call WSCAN to wait for the vertical sync JMP tube_put \ Send A back to the parasite and return from the \ subroutine using a tail call