// Das Blinkenlights
// By F. Prindle
//
// Make digirule 2A look like it's doing something important :)
// Only suitable for the 2A, but see rand-dice6 for random number
// ideas for the 2.
//
// Some handy constants
%define statusRegister      252
%define buttonRegister      253
%define addressLEDRegister  254
%define dataLEDRegister     255
%define mask                7

      // Das Blinkenlights
      speed 8                   // Whatever suits your fancy
      copylr 4 statusRegister   // Enable addressLEDRegister
:loop 
      randa                     // Pick random A bit to set
      andla mask
      copyar bit1+1
      randa                     // Pick random D bit to set
      andla mask
      copyar bit2+1
      randa                     // Pick random A bit to clr
      andla mask
      copyar bit3+1
      randa                     // Pick random D bit to clr
      andla mask
      copyar bit4+1
:bit1 
      sbr 0 addressLEDRegister  // Set random bit in A
:bit2 
      sbr 0 dataLEDRegister     // Set random bit in D
:bit3 
      cbr 0 addressLEDRegister  // Clr random bit in A
:bit4 
      cbr 0 dataLEDRegister     // Clr random bit in D
      jump loop                 // Forever