CoE 243 ALU

Purpose:

1. Become familiar with the 74181 ALU (an MSI device).

2. Be able to get needed information from a data book, instead of simply asking the teacher how.

3. Be able to read and implement a function table.

Procedure:

Connect the 74181 as shown in the data sheet:

    Connect S₃, S₂, S₁ and S₀ to the data switches.

    Connect F₃, F₂, F₁ and F₀ to the display lights.

    Hard-wire M to +5 Volts for logic functions.

    Hard-wire M to GND for arithmetic functions.

    Hard-wire C_n to +5 Volts except where noted.

Hard-wire the following data inputs:

    A₃=1 MSB B₃=1 MSB

    A₂=1     B₂=0

    A₁=0     B₁=1

    A₀=0 LSB B₀=0 LSB

First predict the outcome of various arithmetic and logic functions for all output bits (F₃ through F₀), then check the actual results to see if they match.

For example: The expected output for AB' would be 0100.

Implement the following functions on the 74181, using positive logic:

    A'

    (A + B)'

    (AB)'

    B'

    A XOR B

    AB

    A + B

    A minus B
    (HINT: Use A minus B minus 1 with C_n=0 for A minus B.)

    A plus B