The skip register - page 4

We can add a second register called "notSkip". It is an RCL-only register with no physical bits, and merely inverts the skip bit.

IE, if the skip register is zero, the notSkip register will output a 1, and if skip is 1, notSkip outputs 0. Writing any non-zero to notSkip is the same as writing a 0 to skip, and vice versa.

Thus the instructions "notSkip => skip" or "skip => notSkip" both act identically and will stop skipping if it was skipping, and start skipping if it wasn't skipping. This implements the concept of "else". For example:

   X , -17 => adder => skip   // if ( X == 17)
      A => B ; C => D;        //   do this
   notSkip => skip            // else
      E => F ; G => H;        //   do this
   0 => skip                  // end if

This is of course the equivalent of:

  if (X == 17)
    { A => B; C => D; }
  else
    { E => F; G => H; }
  endIf