Difference between Human and Computer Computers perform complex computation, process a large amount of data, control devices and communicate instantly with high precision Human Humans are capable of performing computation without any instruction, and act according to circumstances From the experience on solving various problems, humans are able to come up with better methods Humans can process non-numeric data

Computer’s components Hardware Physical parts that contain electrical circuits Software (Program) A written program for hardware Hardware alone does not work but together with software, they can be used for various purposes

Hardware

Function and Structure of Hardware 5 major functions of computers: Store, Calculate, Control, Input, Output Central processing Unit（CPU) Input device Processing unit Control unit Ouput device Main memory External memory Control data

General view and function of Hardware CPU 1 Central Processing Unit Control Unit: Manages the instructions and operation of devices in the computer Arithmetic Logic Unit：Executes operations accordingly Data is transferred into CPU from memory Calculation is carried out on the data inside the CPU Data is transferred back to memory from the CPU

General view and function of Hardware CPU 2 Clock A signal generated at a fixed interval to synchronize the operation timing of every part in CPU A shorter clock interval means faster CPU Clock frequency(Hz) The rate of cycles per second of clock signal (How many times clock signal is generated in one second) Generally, the higher the frequency, the faster the CPU

General view and function of Hardware Storage devices 2 main types of Storage device Primary storage (main memory) Read and write speed is fast Data stored in primary memory will be lost when the power is turned off Secondary storage (external memory) Read and write speed is slow Data being stored here will NOT be lost when the power is turned off

General view and function of Hardware Main memory Data will be stored by trapping a charge inside the semiconductor Data being stored here will be lost when the power is turned off Memory slot Main memory

General view and function of Hardware Secondary storage 1 Hard disk Stores data using the alignment of magnet field of particles on the platter’s surface Data is stored on tracks, which is the circular path on the disk surface The head (the silver triangle) is used to read and write from a specific track Hard disk outside Hard disk inside 画像出展：Impress PC Watch Intel Core搭載iMacハードウェアレポート http://pc.watch.impress.co.jp/docs/2006/0117/imac01.htm http://pc.watch.impress.co.jp/docs/2006/0119/imac02.htm

General view and function of Hardware Secondary storage 2 Other secondary storages Floppy disk USB flash disk CD-ROM / CD-R / CD-RW DVD DVD Drive

General view and function of Hardware Performance of Storage Device Capacity How many bytes of data can be stored? Access Speed How many bits of data can be read/written in 1 second? The access speed to main memory is usually several hundreds of thousands times faster than accessing secondary storages.

Main memory and external memory’s role CPU 「Fukuzawa-sensei is a Capricorn」 Main memory Secondary storage 「Fukuzawa-sensei is a Capricorn」

Main memory and external memory’s role Saved as a file Fukuzawa-sensei CPU 「Fukuzawa-sensei is a Capricorn」 Main memory Secondary storage 「Fukuzawa-sensei is a Capricorn」 「Fukuzawa-sensei is a Capricorn」

General view and function of Hardware Input device To deliver user’s intention into computer To insert data into computer Keyboard Pointing devices Mouse Touchpad Pen tablet Scanner Microphone 画像出展　The Apple Store http://store.apple.com/0120-APPLE-1/WebObjects/japanstore.woa/wa/RSLID?nnmm=main&mco=EC571521

General view and function of Hardware Output device To display process results graphically Display LCD CRT Printer Speaker 画像出展　The Apple Store http://store.apple.com/0120-APPLE-1/WebObjects/japanstore.woa/wa/RSLID?nnmm=main&mco=EC571521

【Exercise】 Check your PC specification Check the specification of your PC and fill out the form Manufacturer, Model name HDD or SSD（capacity），CPU(type, frequency），memory(capacity)，OS Weight，display（size, resolution），External drive（type, format），battery lifetime Dimension (width x height x depth) Compare with others’

Software

Software (Program) Hardware can not operate themselves (computer is just a box if there is no software installed) A sequence of instructions that a computer can interpret and execute is called program Different programs can process different data with different methods

What is the different between a computer and a calculator? Procedures and data are in user’s mind Users input data accordingly Input speed is slow Computer (= calculator + memory) Program and data are stored inside (aka Neumann architecture) CPU executes the calculation according to the program High speed computation

Execution of Software Invoking Application CPU Execution Instruction１ Instruction ２ ・・・ Secondary storage Main memory

Execution of Software Input/Output of Data CPU Execution instruction HTML data Secondary storage Main memory

Basic Software and Application Software Also called “application” Used for a specific purpose and task Word processor Software，Spreadsheet Software，Mail Software Basic Software Operating System (OS) Helps applications to run smoothly by controlling the computer Language Processor（Compiler） Converts a high level language to machine language