22 lines
426 B
ArmAsm
22 lines
426 B
ArmAsm
|
|
;;
|
|
;; Official Kernal routine, described in:
|
|
;;
|
|
;; - [RG64] C64 Programmer's Reference Guide - page 304
|
|
;; - [CM64] Compute's Mapping the Commodore 64 - page 224
|
|
;; - https://www.pagetable.com/?p=1031, , https://github.com/mist64/cbmbus_doc
|
|
;;
|
|
;; CPU registers that has to be preserved (see [RG64]): .X, .Y
|
|
;;
|
|
|
|
|
|
untlk:
|
|
|
|
lda #$5F
|
|
sta BSOUR
|
|
jsr iec_tx_command
|
|
bcs + ; branch if error
|
|
jmp iec_turnaround_to_listen
|
|
*
|
|
rts
|