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