#!/usr/bin/wish

frame .b
foreach x { 1 2 3 4 5 6 7 8 } {
  set dx [expr 8-$x]
  button .b.b$dx -text $x -command [list togglebit $x] \
     -fg hotpink
  pack .b.b$dx -side left -padx 2 -pady 4
  set level($x) l
  bind all $x [list togglebit $x]
}

pack .b -side top -fill both -expand true

proc togglebit { x } {
  global level

  if {$level($x) == "l"} {
    set level($x) h
  } else {
    set level($x) l
  }
  
  sendit
}

proc sendit {} {
  global res .b level
  set cmd parcon 
  foreach x { 1 2 3 4 5 6 7 8 } {
    lappend cmd ${x}$level($x)
  }
  
  set res [eval exec $cmd]
  regexp "old = ........\nnew = (........)" $res match binary
 
  for {set x 0} {$x < 8} {incr x} {
    if { [string index $binary $x] == "1" } {
      .b.b$x configure -bg gray90 -rel sunken
    } else {
      .b.b$x configure -bg gray30 -rel raised
    }
  }
}
sendit