; If abort, Carry flag set & ESC is returned in [A]
; All registers unchanged except [A]    (INTEL)
 
GETHEX:
      PUSH  B
      MVI   C,RDCON
      CALL  BDOS        ;Get a character from keyboard & ECHO           
      CPI   ESC
      JZ    HEXABORT
      CPI   '/'         ;check 0-9, A-F
      JC    HEXABORT
      CPI   '9'+1
      JNC   HEXABORT
      CALL  ASBIN       ;Convert to binary
      RLC               ;Shift to high nibble
      RLC
      RLC
      RLC
      MOV   B,A         ;Store it
      PUSH  B
      MOV   C,RDCON
      CALL  BDOS        ;Get 2nd character from keyboard & ECHO
      POP   B           
      CPI   ESC
      JZ    HEXABORT
      CPI   '/'         ;check 0-9, A-F
      JC    HEXABORT
      CPI   '9'+1
      JNC   HEXABORT
      CALL  ASBIN       ;Convert to binary
      ORA   B           ;add in the first digit
      ORA   A           ;To return NC
      POP   B
      RET
;
HEXABORT:
      STC               ;Set Carry flag 
      MVI   A,ESC
      POP   B
      RET
;                       ;Convert LC to UC
UPPER:CPI   'a'         ;must be >= lowercase a
      RC                ; else go back...
      CPI   'z'+1       ;must be <= lowercase z
      RNC               ; else go back...
      SUI   'a'-'A'           ;subtract lowercase bias
      RET
;                       
ASBIN:SUI   30H          ;ASCII TO BINARY CONVERSION ROUTINE
      CPI   0AH 
      RM
      SUI   07H 
      RET