Add Long Instruction

A small addition to the memory addressing logic is needed to support long word instructions. A new control signal ODD indicates that the most significant short word of a long word is being addressed, and forces the LSB of the address to 1.





We can now microcode the long-word variant of the Add instruction as follows.
# OPCODE L STAT : FETCH MASEL SHS EOI RFA1 WRF1 XSEL YSEL CMX AND CY1 CYP ODD

# Add Long
11100 1 0001 : 0 1 0 0 010 1 01 10 0 0 0 0 0
11100 1 0010 : 0 1 0 1 110 1 01 10 0 0 0 1 1

Add Long Test Video

Note: ODD was called MSW when I recorded this video, and was later changed.