19 lines
433 B
ArmAsm
19 lines
433 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 296
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;; - [CM64] Compute's Mapping the Commodore 64 - page 223/224
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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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second:
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and #$1F ; make sure bits encoding the command are cleared out
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ora #$60
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sta BSOUR
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jmp iec_tx_command
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