rx82 0.5.0

An emulator for the RX82 fantasy retro computer system.
Documentation 
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; Print a byte as hex
;
; In:
;   A = byte
    push a
    ld a, 0x30   ; '0'
    trap 0x20    ; print
    ld a, 0x78   ; 'x'
    trap 0x20    ; print
    pop a
    push a
    lsr a, 0x04  ; take upper nibble first
    call NIBBLE_TO_ASCII
    trap 0x20    ; print
    pop a
    and a, 0x0F  ; lower nibble
    call NIBBLE_TO_ASCII
    trap 0x20    ; print
    ret

NIBBLE_TO_ASCII:
    add a, 0x30  ; ASCII '0'
    cmp a, 0x3A  ; digit less than 10?
    bcc NUMERAL
    add a, 0x11  ; ASCII 'A'

NUMERAL:
    ret