Introduction

Question 1

CPU (Central Processing Unit)

Answer 1

the “overworked clerk” performs simple tasks
(ADD/SUB/MUL/DIV/LOGIC).
The task to perform is also known as an “instruction.”

Question 2

Memory

Answer 2

the clerk’s “desk drawers,” a.k.a. the clerk’s “memory.” Each drawer has a number, also known as an address.

Question 3

Program memory

Answer 3

contains instructions for the clerk and tells it what to do.

Question 4

Data memory

Answer 4

contains data for the clerk to work on.

Question 5

Program Counter (PC)

Answer 5

tells the clerk which program memory drawer to open

up and execute.

Question 6

basic parts of a CPU

Answer 6

○ ALU (has no own memory, can only do arithmetic and logic operations)
○ PC
○ Memory for data
○ Memory for instruction

Question 7

Basic Operation of a CPU

Answer 7

○ Program Counter tells clerk which drawer to open up
■ Referred to as instruction “fetching”
○ Clerk examines instruction and performs operation
■ Referred to as instruction “decoding” and “execution”
○ Stores result of instruction in data memory drawer
■ Optional part of the execution of an instruction
○ Updates the program counter (PC)
■ PC = PC + 1 ; so we advance to next instruction upon repeat
■ optionally: PC = some other value ; if we wish to ‘jump’ around to
another part of our program.
○ Repeats this process until instructions are complete
■ Instructions constitute a “program”

Question 8

Algorithm

Answer 8

Step-by-step procedure that is guaranteed to terminate
Procedure:
-Definiteness: each step is precisely stated
-Effective computability: each step can be carried out by computer
- finiteness: procedure terminates