One Bit CPU

Objective of this lab:


	The purpose of this lab is to learn about CPU Organization 
	by building a simplified one bit CPU.


	Read lab lecture notes.

A portion of the CPU is given below. Build it in LogicWorks and test it.

What are control signals EXTout and Cin for?
Design the rest of the CPU according to the description of the CPU in the lab notes and implement the circuit.
Some Relevant Details:

The ALU performs two operations, XOR and AND. The operation to be performed is to be determined by the code in the IR. A 0 in the IR indicates an XOR operation and a 1 indicates an AND operation.

The following control signals will be required for our one bit CPU in this lab:
```
	ACCout, ACCin, TEMPout, TEMPin, ALUout, 

	IRin, Bout, Bin, Cout, Cin, EXTout. 
```
To implement the operation AND, let's assume that it uses the operands in registers B and C, and then stores the result in C,
The following instructions would have to be executed.
(assume the external input switch is set to the value 'one' - the pre-condition for the AND operation):
```
	1. EXTout, IRin.

	2. Bout, ACCin.

	3. Cout, TEMPin.

	4. ALUout, Cin.
```
Practice these microinstructions with your newly built CPU.
Do the following for your lab assignment:
```
 
	Write out the steps necessary to implement the operation XOR 
	that uses the operands in the accumulator and register C, and then 
	stores the result in register B. 
  
```

Hand in the following:

The completed one-bit CPU circuit.
The steps necessary to implement the XOR (described above). Don't forget the pre-condition.

This page last modified:
Friday, 21-Aug-2020 15:22:40 CST

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Copyright: Department of Computer Science, University of Regina.