Structured Computer Organization: Andrew S. Tanenbaum
The 1-bit ALU implements 4 different operations: AND, NOT, OR, ADD.
The current operating mode can be selected via F0 and F1. F0=0 and F1=0 results in A AND B. F0=1 and F1=0 results in NOT B. F0=0 and F1=1 results in A OR B. F0=1 and F1=1 results in A ADD B. Where A and B are the inputs for the operation.
Additional inputs can change the way of operation:
ENB enable/disable the respective input.
INVA inverts A before applying the operation.
CIN is used as input for the full adder.
Multiple 1bit ALUs could be chained to create a wider ALU.
Set the operating mode via the DIP switches with F0 and F1.
Next, set the input with A and B and enable both signals with ENA=1 and ENB=1. If you choose to invert A, set INVA to 1, otherwise to 0. For F0=1 and F1=1 you can set CIN as additional input for the ADD operation.
The 7-segment display shows either a
0 or a
1 depending on the output. If the ADD operation is selected, the dot of the 7-segment display represents the COUT.