Learn an 8-Bit CPU
CPU is the most important part of a computer. It is controlled by
a series of small operations called microoperations.
You have got a feel in the last lab with a one-bit and a two-bit CPU.
In this lab, we will look at an 8-bit CPU and see how it works.
- The difference between absolute vs immediate addressing
- In absolute addressing, the operand is located in
the address specified in the instruction.
For example: NOT 2,B means NOT (or invert) the contents
of location 2, and save it in register B.
- In immediate addressing, the operand is specified in
For example: AND #2,B means AND the value 2,
with register B and save the result in B.
- Students should copy the file: ~ftp/pub/class/301/8bitcpu.cct.
This circuit is simply an extension of what they have already done.
Notice the similarities e.g. temp, accumulator, IR, B and C registers,
and the external input.
- Notice the differences, for example, the memory has a memory address
there is a decoder associated with the ALU,
and there is a PC and an adder to produce a PC+1 value.
Many devices may be connected to a common bus by using tri-state buffers.
This page last modified:
Thursday, 06-Oct-2011 12:13:32 CST
Copyright: Department of Computer Science, University of Regina.