## Computer Hardware

Contents

### Analog Circuits

All circuits are analog circuits.

#### Components

The components of analog circuits are given below.
• resistor (抵抗器)
A resistor is used to limit the flow of current.
• capacitor (condenser) (コンデンサー、キャパシター)
Capacitors can store electrons.
• inductor (coil) (コイル、インダクター)
When current flows through a coil, a magnetic field is created.
• transformer (トランス、変圧器)
A transformer is composed of two coils positioned so that their magnetic fields interact.
• power supply (電源)
In order for a circuit to operate, a power supply must be connected.
• voltage source (電圧源)
A voltage source outputs a constant voltage.
• current source (電流源)
A current source outputs a constant current.
• battery (電池)
A battery is a kind of portable voltage source.
• ground (接地、グラウンド)
Ground is the zero reference point in a circuit.

#### Characteristics

Analog circuits have many characteristics.
• resistance (レジスタンス、抵抗)
Resistance is a measure of how difficult it is for current to flow through a resistor.
• capacitance (キャパシタンス、静電容量)
The amount of charge that a capacitor can store is measured by its capacitance.
• inductance (インダクタンス)
The inductance of a coil is related to its ability to generate magnetic flux.
• impedance (インピーダンス)
Impedance is similar to resistance, but applies to capacitors and inductors as well.
• current (電流)
The movement of electrons in a circuit creates current.
• DC: direct current (直流)
Current that is constant is called DC.
• AC: alternating current (交流)
Current that is changes periodically is called AC.
• phase (位相)
The relative value of an AC waveform can be represented by its phase.
• frequency (周波数)
Frequency is the rate of change of an AC waveform.
• amplitude (振幅)
An AC waveform's amplitude is its maximum value.
• voltage (電圧)
The voltage drop across a resistor is proportional to its resistance.
• peak-to-peak (ピーク間、ピーク−ピーク)
The peak-to-peak voltage of an AC waveform is the voltage difference between the minimum and maximum values of the waveform.
• RMS (root-mean-square) (平方二乗平均)
The RMS voltage of an AC waveform is the value obtained by taking the square-root of the average of the square of the waveform.
• series (直列接続)
The total resistance of two resistors connected in series is the sum of the individual resistances.
• parallel (並列接続) The total capacitance of two capacitors connected in parallel is the sum of the individual capacitances.
• gain (利得、増幅度)
Gain is the ratio of the output voltage to the input voltage in an amplifier circuit.

### Digital Circuits

Digital circuits are special types of analog circuits.

#### Components

The components of a digital circuits are as follows.
• input (入力)
Digital circuits can have one or more inputs.
• output (出力)
A digital circuit processes its inputs to produce one or more outputs.
• NOT gate (inverter)
A NOT gate inverts its input.
• AND gate
The output of an AND gate is true only if all inputs are true.
• NAND gate A NAND gate is an AND gate whose output has been inverted.
• OR gate
The output of an OR gate is true if at least one of the inputs is true.
• NOR gate
If the output of an OR gate is inverted, a NOR gate results.
• XOR (exclusive OR) gate
An XOR gate is similar to an OR gate, but an XOR gate's output is true only if only one of its inputs is true.
• RS flip-flop
The most basic type of memory circuit is an RS flip-flop.
• JK flip-flop
A JK flip-flop is a more complicated memory circuit.
• transistor (トランジスタ)
Digital circuits are made mainly of transistors.

#### Characteristics

Digital circuits have characteristics such as those listed below.
• truth table (真理値表)
The relationship between inputs and outputs is shown in a truth table.
• logic levels: high, low (論理レベル)
The inputs and outputs of most digital circuits use two logic levels referred to as high and low.
• timing chart (タイミングチャート)
The change in logic values as a function of time is called a timing chart.
• propagation delay (伝搬遅延、伝達遅れ時間)
When the input to a digital circuit changes, its output does not change immediately. This time lag is called propagation delay.
• fan-in(ファンイン)
The number of inputs to a digital circuit is its fan-in.
• fan-out(ファンアウト)
The number of inputs that an output of a digital circuit can drive is the output's fan-out.
• TTL(transistor-transistor logic)
One way of making digital circuits is called TTL.
• CMOS (complementary metal oxide semiconductor) (相補型金属酸化膜半導体)
The most common way of making digital circuits today is called CMOS.

### Processors

Processors are the core of a computer.
• CPU (central processing unit) (中央処理装置)
A CPU is the brain of a computer.
• control unit (制御装置)
One component of a CPU is called the control unit.
• data path (データ経路)
Data inside a CPU travels along the data path.
• register (レジスタ)
A register is a small memory inside a CPU.
• bus (バス)
Various devices are connected to each other by a bus.
• CISC (complex instruction set computer) (複雑命令セットコンピュータ)
One type of CPU architecture is called CISC.
• RISC (reduced instruction set computer) (縮小命令セットコンピュータ)
RISC architectures have many advantages over CISC architectures.
• pipelining (パイプライン処理)
One advantage is pipelining.

### Storage Devices

Data is stored in some type of storage device.
• volatile (揮発性)
The contents of a volatile memory is erased when power is removed.
• non-volatile (不揮発性)
The contents of a non-volatile memory remains even when power is removed.
• ROM (Read Only Memory) (読出し専用記憶装置)
Data cannot be written to a ROM.
• PROM (Programmable Read Only Memory) (プログラマブルROM)
A PROM can be programmed only once.
• EEPROM (Electrically Erasable PROM) (電気的消去可能PROM)
The data in an EEPROM can be erased using a special circuit.
• flash memory (フラッシュメモリ)
Flash memory can be rewritten many times.
• RAM (Random Access Memory) (ランダムアクセスメモリ)
All data in a RAM can be accessed in the same amount of time.
• SRAM (Static RAM) (スタティック[静的]RAM)
SRAM has a structure similar to a flip-flop.
• DRAM (Dynamic RAM) (ダイナミック[動的]RAM)
DRAMs must be rewritten periodically or the data will disappear.
• hard disk drive (ハードディスクドライブ)
The most popular type of magnetic storage device is the hard disk drive.
• MO disk drive (Magneto-Optical disk drive) (光磁気ディスクドライブ)
MO disk drives use both magnetic and optical properties to store and read data.
• CDROM
A CDROM uses the same disk as a music CD.
• DVD
A DVD is a new storage format that has a high capacity.
• magnetic tape (磁気テープ)
Magnetic tape is one way to backup data.

### PC Parts

You can build your own PC using the following parts.
• mother board (マザーボード)
The mother board is the main part of a PC.
• CPU
The CPU is inserted into a slot on the mother board.
• memory (メモリ)
The main memory of a PC uses DRAMs.
• case (ケース)
All the components of a PC are placed in a case.
• hard disk (ハードディスク)
The operating system and other files are stored on a hard disk.
• CDROM drive
To install software, a CDROM drive is usually necessary.
• video card (ビデオ・カード)
The video card is necessary to display output from your PC.
• monitor (モニタ)
The video card is connected to a monitor.
• cables (ケーブル)
Many cables are necessary to connect various parts of your PC.
• keyboard (キーボード)
You can input text to your PC using a keyboard.
• mouse (マウス)
A mouse is needed to use graphical user interfaces.