computer systems

1188 110 Computer Programming : Chapter 1.2 – Computer Systems

Computer Systems


Computer Systems

People

Software

Data

Hardware


(cont'd.) Hardware ~ Computer

Physical parts of a computer, including digital electronic circuitry.

Devices for input, processing, and output. Interestingly, microcomputer is only 0.2% of all

computer produced. Most of them are embedded systems.

Software ~ Program Introduced by John W. Tukey in 1958. A program that enables a computer to perform a

specific task, as opposed to the hardware. Consist of a list of instructions that explicitly

implement an algorithm.


(cont'd.) Data, which the system convert into information

Data are everything what is/can be processed. Consist of propositions that reflect reality. Such propositions may comprise numbers, words,

images etc. Information describes a physical or abstract domain. Stored in binary format.

People ~ Users Computer users


Hardware Components Processors Memory Storage devices Input/Output devices


(cont'd.)


The Processors The procedure that transforms raw data into

useful information is called processing. To perform this transformation, the computer uses two components: the processor and memory.

The processor, in a personal computer, usually consists of one or more microprocessors, which are the electronic devices. The microprocessor is plugged into a circuit board, motherboard, containing the circuitry that connects the processor to other hardware.


(cont'd.)

CPU

Memory

ExpansionCard

Motherboard


Central Processing Unit The term central processing unit (CPU) refers to

a computer’s processing hardware, whether it consists of a single chip or several circuit boards.


(cont'd.) The CPU is the brain of the computer, where

data is manipulated. In a microcomputer, the entire CPU is contained

on a tiny chip called microprocessor. The chip has at least two basic parts:

The control unit The arithmetic and logic unit


(cont'd.)

ALU

Data Cache

Bus Interface

Code Cache

Intel® Pentium® CPU Die

FPU

Control

Decode

Fetch


The Control Unit All the computer resources are managed from the

control unit. The CPU’s instructions for carry out commands are built

into the control unit. The instructions, or instruction set, list all the

operations that the CPU can perform. Each instruction in the instruction set is expressed in

microcode - a series of basic directions that tell the CPU how to execute more complex operations.

Different CPUs have different instruction sets. Basic instruction such as moving data from input to

memory, moving data from memory to output.


The Arithmetic and Logic Unit (ALU) Because all computer data is stored as numbers, much

of the processing that takes place involves comparing numbers or carrying out mathematical operations.

The computer can perform only two types of operations: Arithmetic operations Logical operations

When the control unit encounters an instruction that involves arithmetic or logic, it passes that instruction to the ALU.

The ALU includes a group of registers that are used to hold the data currently being processed. Register = high-speed memory built directly inside the

CPU.


Operations Performed by the ALU Arithmetic Operations

+ add- subtract× multiply/ divide^ raise by a power

Logical Operations=, ≠ equal, not equal> greater than≥ greater than or equal< less than≤ less than or equal~ not


Registers The size of the registers, called word size,

indicates the amount of data which the computer can work at any given time.

The bigger the word size, the more quickly the computer can process a set of data.

When we refer to 32-bit processors, or 64-bit processors, or even 64-bit computers, we usually refer to the size of register inside the processor chip.


CPUs used in Microcomputers Intel

CPU Register Max. Memory8086

8088

i386

Pentium

Pentium 4

Core 2

Itanium 9000

16 bits

16 bits

32 bits

32 bits

32 bits

64 bits

64 bits

1 MB

1 MB

4 GB

4 GB

4 GB

1 TB

1 PB

Data Bus16 bits

8 bits

32 bits

64 bits

64 bits

64 bits

64 bits


(cont'd.) Advanced Micro Device (AMD)

Head-to-head since Pentium® Sempron ~ Intel Celeron Athlon 64 ~ Intel Core Opteron ~ Intel Xeon

VIA Technologies Small, cheap, low power consumption C3 C7


(cont'd.)MIPS R4400

PowerPC 970

UltraSPARC T1

Cell


Floating Point Units The ALU in CPU is designed to manipulate

whole numbers that are not too large or too small. If it is forced to work with decimals, it can really get bogged down.

A math coprocessor is a special chip designed to handle complicated mathematical operations. New CPUs have math coprocessor built in.

The math coprocessor uses floating-point arithmetic techniques that translates numbers into the scientific notation, e.g., 0.0000586 → 5.86 x 10-5 128610000000 → 1.2861 x 1011


Parallel Processing A computer with more than one processor

produces faster data processing. The dual-processor and quad-processor versions

of PCs are available today. Also, multi-core processors.

Microsoft Window, Linux, Mac OS, and various UNIX operating system can make use of additional processors.

In parallel processing, multiple processors are used in a single system, enabling them to share processing tasks.


(cont'd.) In a massively parallel processor (MPP) system,

many processors are used. Some MPP systems utilize

thousands of processors simultaneously.

IBM Blue Gene/L


Memory Memory is the computer’s electronic scratch pad.

Program are loaded into and run from memory. Data used by program is also loaded into memory for fast access -- but only temporarily.

Most common type of memory is called Random Access Memory (RAM).

The most common measurement unit for describing a computer’s memory is the byte. Kilobytes (kB) = 1,024 bytes Megabytes (MB) = 1,024 x 1,024 bytes Gigabytes (GB) = 1,024 x 1,024 x 1,024 bytes


(cont'd.) The CPU has no capability to store large sets of

data or entire programs permanently. The CPU has only small space of register.

The CPU needs million of bytes of space where it can hold programs and the data being manipulated while they are being used. This area is called memory.

Memory is an electronic chip. The memory may be soldered on a mainboard or on a small circuit board attached to a mainboard.

There are two types of built-in memory: Volatile and Non-Volatile.


ROM ROM is non-volatile memory chips. Putting data

into this kinds of memory is called “burning-in the data”, and need special tools.

The data in these chips can only be read and used -- it cannot be changed -- so the memory is called Read-Only Memory (ROM).


RAM Memory which is its data can be changed is

called random access memory(RAM). When talking about computer memory, we usually

mean the volatile RAM. Physically, RAM consists of some chips on a

small circuit board.


(cont'd.)

RAM


Current RAM Technologies Synchronous Dynamic RAM (SDRAM)

Synchronize memory bus clock with front side bus (FSB) clock.

Double Data-Rate Synchronous DRAM (DDR SDRAM or just DDR) Operate both rising and falling edge of the clock. DDR2 doubles FSB clock. DDR3 quadruples FSB clock.


(cont'd.) Memory chips usually grouped together on small

circuit boards called Single In-Line Memory Modules (SIMMs) Dual In-Line Memory Modules (DIMMs) Small Outline DIMMs (SO-DIMMs)


The Bus The term bus refers to the electrical paths

between the components of a computer. Actually, the bus is a group of parallel wires.

The motherboard includes an address bus and a data bus. The address bus leads from the CPU to memory

(RAM and ROM). The data bus connects the CPU to memory as well

as all the storage, input/output, and communication devices.


(cont'd.)


Accessing Data in the Memory The CPU stored and retrieves each piece of data

using a memory address. Memory address is a number indicates a

location of data on the memory chips. Memory addresses start at zero and go up to one

less than the number of bytes of memory in the computer.


(cont'd.) Requests for data are sent from the CPU to RAM along the

address bus. The request consists of a memory address. The data comes back to the CPU via the data bus.


Cache Memory Cache memory is

similar to RAM, except that it is extremely fast compared to normal memory.

The cache speeds up processing by storing frequently used data or instruction in its high-speed memory.


Extending the Processor's Power to Other Devices

Ports Printer (parallel) ports Communication (serial) ports USB ports

Expansion Slots and Boards Display cards Sound cards Network interface cards


Ports External devices - such as those used for input

and output - are connected to the system by ports on the back of the computer.

PCs feature a number of built-in ports, which are ready to accept devices such as a printer, mouse, keyboard, phone line, microphone, speakers, and others.

Most computers come with a serial port and a parallel port.


(cont'd.)

PS/2 mouse

PS/2 keyboard

Parallel port

Serial port

USB port

RJ45 socket

Audio jack


(cont'd.)

VGA D-SUB

DVI

HDMI

Firewire port

eSATA


Serial Ports Transmits one bit of data at a time


Parallel Ports Transmit one byte of data at a time


Universal Serial Bus (USB)

USB is a serial bus standard to interface devices.

Designed to allow many peripherals to be connected using a single port.

USB port

Serial port

Parallel port


(cont'd.) Allowing devices to be connected and

disconnected without rebooting the computer. Provide power supply for low-consumption

devices. Allowing many devices to be used without

specific device drivers to be installed. Data rate

Low speed: 1.5 Mbps (USB 1.1 & 2.0) Full speed: 12 Mbps (USB 1.1 & 2.0) Hi-speed: 480 Mbps (USB 2.0) Super-speed: 4.8 Gbps (USB 3.0)


(cont'd.)


Expansion Slots and Cards If the PC does not have a port for an external

device, you can install an expansion card into one of the empty expansion slots.

A card provides the correct port for the new device, and connects the device to the CPU by way of the computer's expansion buses. Peripheral Component Interconnect (PCI) bus

Standard 32/64-bit I/O bus. Accelerated Graphics Port (AGP) bus.

A faster bus for 3D video card.


(cont'd.)

PCIe x16 slot

Modern PCs are now using PCI Express (PCI-E or PCIe).

PCI slot

PCIe x1 slot


(cont'd.) Most common expansion cards

Sound card

Video card

Network Interface Card


Input and Output Devices Input devices accept data and instructions from

user


(cont'd.) Output devices return processed data back to the

user


(cont'd.) Some types of hardware can act as both input

and output devices, e.g., touchscreen. The most common types of devices that can

perform both input and output, however, are communication devices, which connect one computer to another -- a process known as networking.

Modem

Network Interface Card


Storage Devices Storage is a device to hold the data files and the

program files. The three distinctions between storage and

memory: More room in storage than in memory. Contents are retained in storage when the computer is

turned off, whereas the contents in memory disappear. Storage is much cheaper than memory.

The most common storage medium is the magnetic disk. Floppy disk ~ obsoleted by flash drive Hard disk


(cont'd.)