*-----------------------------------------------------------
* Title      : inout
* Written by : rzh
* Date       : February 2014
* Description: echo keyboard input
*-----------------------------------------------------------
       org     $100000

stack  equ     $40000

astat  equ     $700000
actrl  equ     $700000
ainp   equ     $700002
aout   equ     $700002

start:
       dc.l    stack
       dc.l    begin

begin: bsr     sinit
       bsr     inch
       bsr     outch
       bra     begin

sinit: move.b  #3,actrl
       move    #$400,d0
dlay:  subq    #1,d0
       bne     dlay
       move.b  #$15,actrl   ; 8N1,div. 16,non-int.
       rts

inch:  btst    #0,astat
       beq     inch
       move.b  ainp,d0
       rts

outch: btst    #1,astat
       beq     outch
       move.b  d0,aout
       rts

       end    start