CSCI 232 Lab 6

MSI, part deux

In this lab you are going to use a 16x4bit memory chip to implement a 4 bit memory. Originally this lab did a 3 bit memory with the 4^th bit as parity, but after a lot of students had trouble with this, I simplified it a lot. Now all you have to do is hook up 4 switches to the address pins, 4 to the data pins, hook one of the push buttons to the write enable, hook the outputs to LEDs through not gates, and you are done. The hardest part is that the 7489 is not in LogicWorks, so you will need to draw it yourself. All you need to do is draw a box with 16 lines out of it. Outside the box, the lines should have pin numbers on them, while inside the box they should have pin names or functions. This is one of the simplest circuits we have built this semester since it is just the 7489, a 7404 for 4 NOT gates, some switches, and some LEDs.

To test your circuit I’m going to store various values at certain memory locations, then go back to those locations and make sure the values are still there. As long as the values are still there, I’ll sign off on your circuit.

Note: As usual, simulate this circuit in LogicWorks first, and get it approved before actually wiring it on the CADET. Also, some of you are leaving the lab a mess—not cleaning up the CADET’s when you are done with them, not putting away your chips or wires in the proper bins, not putting the CADET’s back in 255 when you are done with them, etc. This is considered part of the lab just like modeling or wiring the circuit is! If I have to, I will start deducting points for groups who leave messes!

Anyway, good luck and have fun!