trying to send nmra doesn't work:
 8a 67		8a 67
 ff ff 7f	no response
 8a 55		8a 55
 etc.

led is wrong when we just run the program ?  surely it should be red

points do not finish changing and cdu does not recharge


residual stuff from CDU is present and changes pt0 when you
  * turn on
  * say `+' to master to turn on CDU
  * switch to programming mode
 pt0 on pic2 is the one nearest the switch box, moving to hacker's right
 (we think - I haven't checked this yet)


layout polarity diagram colourful segment encoding:
 make moveable feature selection in subseg2display bitwise rather than
  setwise

safety system no crashes at crossovers please