First, let's go over once again a few particulars about the memory organization and data in the CSC-1 computer.

• All addresses are 12 bits long.
• Memory is word addressable, with words being 16 bits.

This last means that the values that can be stored in registers and in memory words are:

-32768 to +32767      for signed values (2's complement)
0 to 65535            for unsigned values

All values are actually stored as unsigned. The C, N, Z and V bits are set appropriately when the A register is changed. You may input numbers as signed (within the range -32768 to +32767) and the program will convert them to their unsigned counterparts. For example, -1 is 65535.