;********************************
;** Function: byte_to_bcd
;** Purpose:  Convert a single byte into two BCD digits
;** Input: A   = Byte to convert (0x00-0xFF)
;** Output: A = High nibble (ASCII 0x30-0x39,0x41-0x46)
;**           R0 = Low nibble (ASCII 0x30-0x39, 0x41-0x46)
;** Destroyed Registers: None 
;********************************
byte_to_bcd:
    MOV     R0,A
    ANL     A,#0Fh
    ADD     A,#0F6h
    JNC     byte_to_bcd_2
    ADD     A,#07h
byte_to_bcd_2:
    ADD     A,#3Ah
    XCH     A,R0
    SWAP    A
    ANL     A,#0Fh
    ADD     A,#0F6h
    JNC     byte_to_bcd_3
    ADD     A,#07h
byte_to_bcd_3:
    ADD     A,#3Ah
    RET