;; ;; Official Kernal routine, described in: ;; ;; - [RG64] C64 Programmer's Reference Guide - page 301/302 ;; - [CM64] Compute's Mapping the Commodore 64 - page 223 ;; - https://www.pagetable.com/?p=1031, https://github.com/mist64/cbmbus_doc ;; ;; CPU registers that has to be preserved (see [RG64]): .X, .Y ;; ;; XXX shouldn't this do a turnaround? talk: ;; First check whether device number is correct jsr iec_devnum_check bcs kernalerror_DEVICE_NOT_FOUND ;; Encode and execute the command ora #$40 sta BSOUR jmp iec_tx_command