Page 66 - DCAP210_INTRODUCTION__TO_MICROPROCESSORS

Introduction to Microprocessors

Notes other times. Several common computer security problems arise because modern processors are
not pure Harvard systems and manipulate instructions as if they were data, and vice versa.

4.2.12 Dual-Core vs Quad-Core Architecture
Many microprocessors made by Intel and AMD are multi-core processors. What this means is
that within one microprocessor, there are two or more central processing units (cores) within one
integrated circuit package.
As their names imply, “dual-core” multiprocessors have two CPU cores in the multiprocessor
package, and “quad-core” multiprocessors have four CPU cores. Depending upon the software
being used, the operating system the computer system has installed and the amount of memory
available to the computer system, a quad-core system is capable of running more simultaneous
processes than a dual-core system.
However, some older software or operating systems (such as Windows 95, Windows 98 or
Windows Me) are not capable of utilizing multi-core microprocessors. If the software or operating
system is incapable of utilizing the resources available, using a multi-core microprocessor is no
different than using a single-core microprocessor.

4.3 Microprocessor Operations

A microprocessor manipulates data in a computer system. The central processing unit acts as the
brain of a computer and consists of one or more microprocessors made up of several thousand
transistors on a single integrated circuit. The microprocessor works in conjunction with other
parts of the computer to compute arithmetic and logic functions to handle tasks using an instruction
set to perform all tasks within a computer.
4.3.1 Input and Output
The microprocessor accepts input from devices, such as a mouse, keyboard or scanner, and
performs a function on that data. It makes a decision based on the data, the microprocessor
computes the information and then it sends the results to the output devices, such as a monitor or
printer, as readable information for the user. For example, if a user using a word processor presses
“m” on the keyboard, the microprocessor will accept that and send the letter “m” to the monitor.
Input/Output Devices

Keyboards, Floppy disk are the examples of input devices. Printer, LED / LCD display, CRT
Monitor are the examples of output devices.
4.3.2 Arithmetic Logic Unit

The arithmetic logic unit gathers information as input from the CPU registers and operands and
then does the arithmetic operations (addition, subtraction, multiplication and division) and logic
operations (AND, OR and XOR). During data processing, the ALU tests conditions and prepares to
take different actions based on results. The ALU also gathers data from additional sources, including
number systems, instructions, timing and data routing circuits, such as adders and subtracters.
4.3.3 Memory

The microprocessor accesses and stores binary instructions into memory, or circuits that store
bits. Random access memory is a control memory that uses registers to temporarily store data.
The microprocessor stores volatile data used by programs in RAM. Read-only memory stores
data permanently on chips with instructions built in. It takes longer to access the information in
ROM, but it does not lose information when a computer shuts down as does RAM.
4.3.4 Control Unit
The control unit directs the flow of operations and data by selecting one program statement at a
time, interpreting it and sending messages to the ALU or registers to carry out the instruction. It

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