sl         ; *2 
  sta escape_parameter    ; = 10a
  ; add new digit
  pla         ; resore new digit
  clc
  adc escape_parameter
  sta escape_parameter
  jmp @next_digit     ; next char        
@done:
  rts        


        
; *************************************
; *
; * outgoing data
; *
; *************************************
; -------------------------------------
; given a single char (read from keyboard)
; work out what data should be sent to the remote host.
; input:
; A = ke