Hardware Von Neumann Architecture_presentation_2 variant

Von Neumann architecture – 2 lesson

Learning objectives:

Describe the features of a control unit (CU), arithmetic logic unit (ALU), and a memory register as separate parts of the processor

“Find a mistake.”

Activity

The Von Neumann Architecture

Video:[The Von Neumann Architecture]

Von Neumann Architecture

5

Memory (Program and Data)

Control Unit

Arithmetic and Logic Unit

Input

Output

John von Neumann in the 1940s

Harvard Architecture

6

Memory (Program)

Control Unit

Arithmetic and Logic Unit

Input

Output

Memory (Data)

-Gordon Moore - cofounder of Intel;
-Since 1970’s development has slowed a little;
-Number of transistors doubles every 18 months;
-Cost of a chip has remained almost unchanged;
-means shorter electrical paths, giving higher peHigher packing density rformance;
-Smaller size gives increased flexibility;
-Reduced power and cooling requirements;
-Fewer interconnections increases reliability;

CPU

The processor (or Central Processor Unit - CPU) is one of the most complex parts of any computer system. The processor executes programs and supervises the operation of the rest of the system. Single chip processors are otherwise known as microprocessors. 

The Von Neumann Architecture

CMPUT101 Introduction to Computing

(c) Yngvi Bjornsson

9

Memory

Processor (CPU)

Input-Output

Control Unit

ALU

Bus

The ALU Subsystem

The ALU (Arithmetic/Logic Unit) performs
mathematical operations (+, -, x, /, …)
logic operations (=, <, >, and, or, not, ...)
In today's computers integrated into the CPU

CMPUT101 Introduction to Computing

(c) Yngvi Bjornsson

10

Circuits to do the arithmetic/logic operations.

Registers (fast storage units) to store intermediate computational results.

Bus that connects the two.

ALU

Some examples of assembly code instructions that would use the ALU are as follows (not all processors will have all these instructions):

ADD ;add one number to another number
SUB ;subtract one number to another number
INC ;increment a number by 1
DEC ;decrements a number by 1
MUL ;multiply numbers together
OR ;boolean algebra function
AND ;boolean algebra function
NOT ;boolean algebra function
XOR ;boolean algebra function
JNZ ;jump to another section of code if a number is not zero (used for loops and ifs)
JZ ;jump to another section of code if a number is zero (used for loops and ifs)

Structure of the ALU

Registers:
Very fast local memory cells, that store operands of operations and intermediate results.
CCR (condition code register), a special purpose register that stores the result of <, = , > operations
ALU circuitry:
Contains an array of circuits to do mathematical/logic operations.
Bus:
Data path interconnecting the registers to the ALU circuitry.

CMPUT101 Introduction to Computing

(c) Yngvi Bjornsson

12

ALU circuitry

R0

R1

R2

Rn

The Control Unit

Program is stored in memory
as machine language instructions, in binary
The task of the control unit is to execute programs by repeatedly:
Fetch from memory the next instruction to be executed.
Decode it, that is, determine what is to be done.
Execute it by issuing the appropriate signals to the ALU, memory, and I/O subsystems.
Continues until the HALT instruction

CMPUT101 Introduction to Computing

(c) Yngvi Bjornsson

13

Bus-Oriented Computer Architecture

14

Data Bus

Address Bus

Control Bus

CPU

Memory

I/O Device 1

I/O Device n

…

Draw the Von Neumann Architecture

Activity

Answer to the questions in worksheet file.