Basic Schematic of Computer System
Substance
- Computer System Components
- Processor
- Memory
- Input/Output Devices
- Inter-Component Interconnection (BUS)
- Execute Instructions
- Instruction Execution Mode
Computer System Block
1. Computer System Components
a. Processor
Functions to control computer operations & perform data processing functions.
b. Main memory
- Functions to store data & programs
- Usually volatile: cannot retain stored data & programs when the energy source (electricity) is stopped.
c. Input and output devices
function to move data between the computer and the external environment, namely: secondary storage devices, communication devices, terminals, etc.
d. Interconnection between components (bus)
is a structure & mechanism for connecting the processor, main memory, & input/output devices.
2. Processing
Functions to control computer operations & perform data processing functions. Steps taken by the processor:
- fetch binary encoded instructions from main memory
- decoding instructions into simple actions
- carry out action -- action
Operations on a computer can be categorized into 3 types, namely:
- Arithmetic operations: +,-,*, etc.
- Logical operations: OR, AND, XOR, inversion, etc.
- Control operations: branching, jumping, etc.
The processor consists of:
- CU (Control Unit): functions to control the operations carried out by the computer system.
- ALU (Arithmetic Logic Unit): for computing, namely performing arithmetic & logic operations
- Registers: function as very fast memory which is usually where the operands of the operations to be performed are located.
Processing Block Scheme
Registers can be categorized into 2:
3. Registers visible to the user (programmer)
Programmers can check the contents of these types of registers. Several instructions are provided to fill (modify) these types of registers. Consisting of 2 types:
a. Data Register, stores a value for various purposes:
- General purpose register, Used for various purposes in a machine instruction that performs an operation on data.
- Special purpose register, Used to accommodate floating point operations, accommodate overflow of addition or multiplication operations.
b. Address Register, contains the data address in main memory, the instruction address in main memory, the address section used in calculating the complete address:
- Index Register, Indexed addressing is one of the popular addressing modes. Addressing involves adding an index to the base value to obtain an effective address.
- Segment pointer register, In segmented addressing, memory is divided into segments. A segment contains a block of memory that can vary in length. To refer to segmented memory, a reference to the segment and an offset in that segment are used. The segment pointer register records the base address (starting location) of the segment. Segmented addressing modes are very important in memory management.
- Stack pointer register, Instructions that do not require an address because the operand address is pointed to by the stack pointer register. Operations on the stack:
> push instruction: stores data on the stack, by placing the data at the top of the stack
> pop instruction: takes data from the top of the stack.
- Flag register, The contents of the register are the results of the processor's operations. The register contains conditions produced by the processor related to the operation that has just been executed. This register is visible to the user but can only be updated by the processor as a result of the operation it has executed.
4. Register for control & status
Used to control processor operations, most of them are invisible to the user. Some are accessible by machine instructions executed in the operating system's control or kernel mode.
a. Registers for addresses and buffers, consisting of:
- MAR (Memory Address Register), to record the memory address to be accessed (either to be written or read)
- MBR (Memory Buffer Register), to accommodate data that will be written to memory whose address is designated by MAR or to accommodate data from memory (whose address is designated by MAR) that will be read.
- I/O AR (I/O Address Register), to record the address of the I/O port to be accessed (whether to be written / read).
- I/O BR (I/O Buffer Register), to accommodate data that will be written to the port whose address is designated by I/O AR or to accommodate data from the port (whose address is designated by I/O AR) that will be read.
b. Register for instruction execution
- PC (Program Counter), records the memory address where the instructions in it will be executed.
- IR (Instruction Register), holds the instructions to be executed
c. Register for status information
This register is a single register/collection of registers. This collection of registers is called PSW (Program Status Word). PSW contains processor condition codes plus other status information, namely:
- Sign, This flag records the sign produced by the previously executed operation.
- Zero, This flag records whether the previous operation resulted in a zero value.
- Carry, This flag records whether a carry is generated (a condition where an addition/multiplication operation produces a carry that cannot be accommodated in the accumulator register)
- Equal, This flag records whether the operation results in an equal condition.
- Interrupt enable/disable, This flag records whether interrupts are enabled or not.
- Supervisor, This flag records the execution mode that is executed, namely supervisor mode or not. In supervisor mode, all instructions can be executed, while for non-supervisor mode (user mode), some critical instructions cannot be activated.
5. Memory
Memory serves to store data and programs. Memory hierarchy based on access speed:
Memory Hierarchy Based on Access Speed
- Price: the lower you go, the cheaper the price, the price is calculated from the ratio of rupiah per bit of data stored.
- Capacity: the lower you go, the more limited the capacity.
- Access speed: the lower it is, the slower it is.
- Access frequency: the lower you go, the lower the access frequency.
Every time the processor executes, the processor must read instructions from the main memory. In order for the execution to be done quickly, instructions must be made available in memory at a higher access speed layer. This execution speed will increase system performance. This concept is implemented in the following ways:
Cache memory
It is a limited capacity, high-speed memory that is more expensive than main memory. Cache memory is between main memory and processor registers that function so that the processor does not directly refer to main memory but to cache memory which has higher access speed. This method will improve system performance.
Buffering
The main memory section to accommodate data to be transferred from/to input/output devices and secondary storage. Buffering can reduce the frequency of access from/to input/output devices and secondary storage, thereby improving system performance.
6. Input / Output Devices
Input/output devices consist of 2 parts:
- Mechanical components: the device itself
- Electronic components: device controller in the form of a controller chip
A device is a physical device controlled by a controller chip on a system board or card. The controller is connected to the processor and other components via a bus. Controllers vary, but usually have registers to control them.
7. Inter-Component Interconnection (BUS)
Buses consist of 3 types:
1. Address bus
The CPU sends the address of the memory location or port to be written or read on the address bus.
2. Data bus (data bus)
CPU can read & send data from/to memory or ports. Many devices on the system are connected to the data bus but only one device at a time can use it.
3. Control bus
The CPU sends signals on the control bus to command memory or ports. Control bus signals include:
- memory read : command to read memory
- memory write : command to write memory
- I/O read: commands read I/O port
- I/O write: instructs to write memory
Example of reading mechanism
To read data from a memory location, the CPU sends the desired memory address through the address bus and then sends a memory read signal on the control bus. The memory read signal instructs the memory device to output the data at that location to the data bus for the CPU to read.
8. Execution of Instructions
Instruction processing stages:
- The processor reads instructions from memory (fetch)
- The processor executes instructions (execute)
Program execution consists of fetch and execute repetitions. Processing 1 instruction is called one instruction cycle. Instruction execution cycle:
Instruction execution cycle
9. Instruction Execution Mode
1. User mode:
Mode with low authority, user programs (applications) are usually executed in this mode.
2. System mode
High-authority mode. Usually system routines or controls or kernels are executed in this mode.
Getting to Know Computer Systems
A computer system consists of three elements, namely:
- Hardware (Hardware), is an electronic circuit
- Software is a program that runs on a computer.
- Brainware (HR).
Hardware
Computer hardware generally consists of three main components, namely:
1. Processor
It is a part of computer hardware that performs arithmetic and logic processing and controls the overall operation of the computer. The processor consists of two main parts, namely the ALU (Arithmetic Logic Unit) and the Control Unit.
The working speed of the processor is usually determined by the clock speed of its Control Unit. Example: if the processor has a clock frequency of 350 MHz, it means the processing speed of one instruction = T = 1/f = 1/(350 x 106 Hz), = 0.286 x 10-8 seconds.
2. Memory
Based on its function, it is divided into two, namely:
a. Primary Memory, used to store data and instructions from programs that are running. Also known as RAM. The characteristics of primary memory are:
- Volatile (information exists as long as the computer is running. When the computer is turned off, the information it stores is also lost)
- high speed
- random access.
b. Secondary Memory, used to store binary data or programs permanently. The characteristics of secondary memory are:
- non volatile or persistent
- relatively low speed (compared to primary memory)
- random or sequential access
Examples of secondary memory: floppy, hard disk, CD ROM, magnetic tape, optical disk, etc. Of all these examples, the one that has a sequential access mechanism is magnetic tape.
Input-Output Device, is a part that functions as a link between the computer and the environment outside it. Can be divided into two groups, namely:
a. Input Device (Input Device), functions as a computer media to receive input from outside. Some examples of input devices:
- keyboard
- mouse
- touch screen
- scanner
- camera
- modem
- network card
- etc.
b. Output Device (Output Device), functions as a computer media to provide output. Some examples of input devices:
- Monitor
- Printer
- Speaker
- Plotter
- Modem
- network card
- etc.
Software
Software can be classified as follows:
- Operating System, is software that operates a computer and provides an interface with other software or with the user. Examples of operating systems: MS DOS, MS Windows (with various generations), Macintosh, OS/2, UNIX (with various versions), LINUX (with various distributions), NetWare, etc.
- Utility Programs are special programs that function as computer maintenance tools, such as anti-virus, hard disk partitions, hard disk management, etc. Examples of utility program products: Norton Utilities, PartitionMagic, McAfee, etc.
- Application Program, is a program developed to meet specific needs. Examples: accounting applications, banking applications, manufacturing applications, etc.
- Package Program, is a program developed for general needs, such as:
- word processor/manuscript editor: Wordstar, MS Word, Word Perfect, AmiPro, etc.
- Number processor / spreadsheet: Lotus123, MS Excel, QuattroPro, etc.
- presentation : MS PowerPoint, etc.
- graphic design: CorelDraw, PhotoShop, etc.
The programming language of a computer system consists of three elements, namely:
- Hardware (Hardware), is an electronic circuit
- Software is a program that runs on a computer.
- Brainware (HR).
Hardware
Computer hardware generally consists of three main components, namely:
1. Processor
It is a part of computer hardware that performs arithmetic and logic processing and controls the overall operation of the computer. The processor consists of two main parts, namely the ALU (Arithmetic Logic Unit) and the Control Unit.
The working speed of the processor is usually determined by the clock speed of its Control Unit. Example: if the processor has a clock frequency of 350 MHz, it means the processing speed of one instruction = T = 1/f = 1/(350 x 106 Hz), = 0.286 x 10-8 seconds.
2. Memory
Based on its function, it is divided into two, namely:
a. Primary Memory, used to store data and instructions from programs that are running. Also known as RAM. The characteristics of primary memory are:
Volatile (information exists as long as the computer is running. When the computer is turned off, the information it stores is also lost)
high speed
random access.
b. Secondary Memory, used to store binary data or programs permanently. The characteristics of secondary memory are:
non volatile or persistent
relatively low speed (compared to primary memory)
random or sequential access
Examples of secondary memory: floppy, hard disk, CD ROM, magnetic tape, optical disk, etc. Of all these examples, the one that has a sequential access mechanism is magnetic tape.
Input-Output Device, is a part that functions as a link between the computer and the environment outside it. Can be divided into two groups, namely:
a. Input Device (Input Device), functions as a computer media to receive input from outside. Some examples of input devices:
- keyboard
- mouse
- touch screen
- scanner
- camera
- modem
- network card
- etc.
b. Output Device (Output Device), functions as a computer media to provide output. Some examples of input devices:
- Monitor
- Printer
- Speaker
- Plotter
- Modem
- network card
- etc.
Software
Software can be classified as follows:
- Operating System, is software that operates a computer and provides an interface with other software or with the user. Examples of operating systems: MS DOS, MS Windows (with various generations), Macintosh, OS/2, UNIX (with various versions), LINUX (with various distributions), NetWare, etc.
- Utility Programs are special programs that function as computer maintenance tools, such as anti-virus, hard disk partitions, hard disk management, etc. Examples of utility program products: Norton Utilities, PartitionMagic, McAfee, etc.
- Application Program, is a program developed to meet specific needs. Examples: accounting applications, banking applications, manufacturing applications, etc.
- Package Program, is a program developed for general needs, such as:
- word processor/manuscript editor: Wordstar, MS Word, Word Perfect, AmiPro, etc.
- Number processor / spreadsheet: Lotus123, MS Excel, QuattroPro, etc.
- presentation : MS PowerPoint, etc.
- graphic design: CorelDraw, PhotoShop, etc.
- Programming Language, is software for creating or developing other software. Programming languages can be classified into low level, medium level, and high level. The shift from low to high level indicates closeness to 'human language'. Low level language (or commonly called assembly language) is a language with one-by-one mapping to computer instructions. Examples of high level languages: Pascal, BASIC, Prolog, Java etc. Examples of medium level languages: C language. Like other software, programming languages also have generation growth.
HR
There are various roles that humans can play in a computer system. Some of these roles are:
- Systems Analyst, plays a role in analyzing the problems faced, and designing solutions in the form of computer programs.
- Programmers, whose role is to translate designs made by analysts into programming languages so that the solutions can be run by computers.
- Operator, in charge of running the computer based on the instructions given
- Technician, tasked with assembling or maintaining computer tap devices
- dll.an, is software for creating or developing other software. Programming languages can be classified into low-level, medium-level, and high-level. The shift from low to high level indicates closeness to 'human language'. Low-level languages (or commonly called assembly languages) are languages with one-by-one mapping to computer instructions. Examples of high-level languages: Pascal, BASIC, Prolog, Java etc. Examples of medium-level languages: C language. Like other software, programming languages also have generational growth.
HR
There are various roles that humans can play in a computer system. Some of these roles are:
- Systems Analyst, plays a role in analyzing the problems faced, and designing solutions in the form of computer programs.
- Programmers, whose role is to translate designs made by analysts into programming languages so that the solutions can be run by computers.
- Operator, in charge of running the computer based on the instructions given
- Technician, tasked with assembling or maintaining computer tap devices
- etc.
Relationship between Computer Systems & Electronics
If you have ever opened or looked inside an electronic device, then you will find a condition similar to Figure 3.1. above. There are circuit boards, interconnected cables, and other electronic devices. Electronic devices like these are also what make up a computer device. So understanding electronics, digital electronics and computer systems is important for those of you who want to get involved in the world of software engineering.
Figure 3.1. Electronic circuits and devices
And digital electronics engineering, especially those related to computer systems. There are two basic competencies in the basic electronics engineering competency standards, namely understanding basic electronics principles and knowing basic electronics components. While the competency standards for digital electronics engineering consist of basic competencies in mastering digital electronics engineering and mastering digital electronics engineering for computers. In the presentation in this book, each basic competency contains a description of the material. The summary is placed at the end of the chapter. Before studying this competency, remember about basic electronics engineering and supporting materials from mathematics subjects.
Objective
After studying this chapter, it is expected that you will be able to:
- Master basic electronics concepts.
- Knowing the electronic components.
- Master the concept of digital electronics.
- Mastering digital electronics and computer systems.
1. Basic Concepts of Electronics
Electronics is the science that studies weak current electrical devices that are operated by controlling the flow of electrons or electrically charged particles in a device such as computers, electronic equipment, thermocouples, semiconductors, and so on. The science that studies such devices is a branch of physics, while the design and manufacture of electronic circuits is part of electrical engineering, computer engineering, and electronics and instrumentation science/engineering.
Tools that use the basic working of electronics are usually called electronic devices. Examples of these electronic devices/equipment: Cathode Ray Tube (CRT), radio, TV, cassette recorder, video cassette recorder (VCR), VCD recorder, DVD recorder, video camera, digital camera, desktop personal computer, laptop computer, PDA (pocket computer), robot, smart card, etc.
As mentioned above electronics is based on the knowledge of electricity. Electricity, can be defined as follows:
- Electricity is a condition of certain subatomic particles, such as electrons and protons, that causes attractive and repulsive forces between them.
- Electricity is a source of energy that is distributed through cables. Electric current occurs because electric charges flow from the positive channel to the negative channel.
There are 2 types of electric charge: positive and negative. Through experiments, like charges repel each other and opposite charges attract each other. The magnitude of this attractive and repulsive force is determined by Coulomb's law. Coulomb's law is a law that explains the relationship between the force that arises between two point charges, separated by a certain distance, with the value of the charge and the distance between them. The SI unit of electric charge is the coulomb, which has the abbreviation "C". The symbol Q is used in equations to represent the quantity of electricity or charge. For example, "Q=0.5 C" means "the quantity of electric charge is 0.5 coulomb".
If electricity flows through special materials, such as tungsten and tungsten, incandescent light will be emitted by the metal. Such materials are used in light bulbs (bulblamps or bulbs). Whenever electricity flows through a material that has resistance, heat will be released.
The greater the electric current, the heat generated will multiply. This property is used in iron elements and electric stoves.
Electrical resistance is the ratio between the electrical voltage of an electronic component (for example a resistor) and the electrical current passing through it. Electrical resistance can be formulated as follows:
where V is voltage and I is current.
Voltage (sometimes called Voltage) is the difference in electrical potential between two points in an electrical circuit, and is expressed in volts. It measures the potential energy of an electric field that causes an electric current to flow in an electrical conductor. Depending on the difference in electrical potential, a voltage can be described as extra low, low, high or extra high.
Electric current is the amount of electric charge that flows per unit of time. Electric charge can flow through cables or other electrical conductors.
In ancient times, conventional current was defined as the flow of positive charge, although we now know that electric current is produced by the flow of negatively charged electrons in the opposite direction. The SI unit for electric current is the ampere (A).
2. Electronic Components
Resistor
Resistors are basic electronic components used to limit the amount of current flowing in a circuit. As the name implies, resistors are resistive and are generally made of carbon. The unit of resistance of a resistor is called Ohm or symbolized by the symbol W (Omega). The common type of resistor is in the form of a tube with two copper legs on the left and right. On its body there is a circle forming a color code bracelet to make it easier for users to recognize the amount of resistance without measuring its size with an Ohmmeter.
Capacitor
A capacitor is an electronic component that can store an electric charge. The structure of a capacitor is made of 2 metal plates separated by a dielectric material. Commonly known dielectric materials include vacuum air, ceramics, glass and others. If both ends of the metal plate are given an electric voltage, then the positive charges will collect on one of the metal legs (electrodes) and at the same time the negative charges will collect on the other end of the metal.
Inductor
An inductor is a component that can store magnetic energy. This energy is represented by the presence of an emf (electromotive force) voltage if the inductor is electrified. The main function of an inductor in a circuit is to counteract the fluctuations in the current passing through it. One of its applications in a DC circuit is to produce a constant DC voltage against fluctuations in the current load. In an AC circuit application, one of its uses is to dampen unwanted changes in current fluctuations. There will be many more functions of inductors that can be applied to filter circuits, tuners and so on.
3. Understanding Digital Electronics
Digital electronics are electronic systems that use digital signals. Digital signals are based on signals that are discontinuous. Usually symbolized by the algebraic notation 1 and 0. The notation 1 symbolizes the occurrence of a connection and the notation 0 symbolizes the absence of a connection. The easiest example to understand this concept is a light switch. When you press ON, it means there is a connection so it is denoted as 1. When you press OFF, the opposite will apply.
various fields such as computers, mobile phones and various other devices. This is because digital electronics have several advantages, including: digital systems have an interface that is easy to control with computers and software, storing information is much easier in digital systems compared to analog. However, digital systems also have several disadvantages, namely: in some cases digital systems require more energy, are more expensive and fragile.
4. Logic Gates
Digital electronics or any digital circuit is made up of what are called logic gates. Logic gates perform logical operations on one or more inputs and produce a single output. The resulting output is the result of a series of logical operations based on the principles of Boolean algebra. In electronic terms, these inputs and outputs are realized and voltage or current (depending on the type of electronics used).
Each logic gate requires power to be used as a source and a sink for current to obtain the appropriate voltage. In logic circuit diagrams, power is usually not listed.
In its application, logic gates are the building blocks of electronic hardware. These logic gates are made using transistors. How many transistors are needed depends on the form of the logic gate. The basis for forming a logic gate is a truth table. There are three basic forms of truth tables, namely AND, OR, and NOT. The following are the tables and forms of logic gates.
Figure 3.5. Truth table and its representation in logic gates.
The explanation of Figure 3.5 above is as follows:
- In AND, if there are two inputs A and B then the output or signal is only produced if A = 1 and B = 1.
- In OR, if there are two inputs A and B then an output or signal will be produced if one or both inputs is 1
- In NOT, if one input has a certain value, the NOT operation will produce an output/signal that is the opposite of the input value.
In addition to the basic forms above, several forms that are derived from the basic forms are also important to know. Figure 3.6. shows the truth table and logic gates of NAND, NOR, and XOR. NAND is the result of NOT + AND operation, NOR is NOT + OR operation while XOR is exclusive OR. NAND and NOR are logic gate forms that are widely used to build digital electronic devices.
Figure 3.6. Derived form of truth table and its representation in logic gates.
5. Digital Circuits
In the sub-chapter above we have learned about the forms of logic gates based on the truth table. A digital circuit is actually composed of one or more of these logic gates. Consider the example in Figure 3.7. below. If we look at the image, at the top there are four NAND logic gate notations, one pin for a 5 V power source and one pin for ground. While at the bottom is a representation of this digital circuit, namely a 7400 chip.
Figure 3.7. Example of a digital circuit and its representation in hardware.
6. Computer System
The term computer comes from the Latin "Computare" which means to calculate. Therefore, actually every tool that functions as a calculating tool such as an adding machine, calculator, or even an abacus can technically be called a computer. However, in its development, computers have different meanings.
A computer is an electronic data processing tool that works and is controlled by a set of instructions (programs) (Blissmer, 1985). A computer system is a collection of elements, namely humans, hardware, and software that interact with each other to achieve goals, namely obtaining useful information, ease of work, speed and other goals.
There are three main components in a computer system, namely humans as users, hardware and software (Figure 3.8). If one is missing, the computer system will not work. For example, if there are only humans and hardware, the computer system will not work because there is no program to help humans run the hardware.
Figure 3.8. Computer System
7. Hardware
Hardware is all the physical parts of a computer. Hardware is distinguished by the data it contains or operates on, and the software that provides instructions for the hardware to complete its tasks. In general, there are four basic components of a computer that are interrelated (See Figure 3.9).
Figure 3.9. Basic components of a computer
Input Unit, which is a device that allows users to enter data or commands into a computer. Examples of devices included in the input unit are; keyboard, mouse, joystick, and digitizer.
Output Unit, which is a device that allows users to receive information processed by the computer. Examples of devices included in the output unit are: monitors, printers, and plotters.
Main Memory Unit, which is a device used to store data, programs, and information processed by the computer during processing. The main memory unit consists of many cells, each of which can store one unit of information. The main memory unit consists of two parts, namely ROM (Read Only Memory) and RAM (Random Access Memory). ROM can only be written once and then can only be read. RAM can be written, erased and read repeatedly. Data, programs, and information being processed are stored in this RAM, and will be lost when the computer is turned off. That is why data, programs, and information that will be used again are stored in additional storage media (secondary storage) such as hard disks, diskettes, CDs, tapes and others.
Central Processing Unit, which is the part used to process data, programs, and information on a computer. There are two important parts in the CPU, namely the Arithmetic and Logical Unit (ALU) and the Control Unit. Many people say that the ALU is the heart of a computer. The ALU is responsible for two basic operations, namely arithmetic and comparison operations. While the Control Unit is responsible for coordinating all activities of other units, for example how the keyboard can be recognized and works as an input unit whose activities are understood.
Physically, the general architecture of a computer that we are familiar with (Personal Computer/PC) can be seen in Figure 3.10. A PC is a series of various components that each have their own function.
Figure 3.10. Computer hardware
The following is a brief explanation of the physical components in a computer:
1. Display
The display or monitor component is included in the output unit of a computer. A cable connects the monitor to the video adapter installed in the motherboard expansion slot. The computer sends signals to the video adapter, about what characters, images or graphics should be displayed. The video adapter will convert the signals into a set of instructions on how the monitor should display text, or images on its screen.
Figure 3.11. Display or monitor
2. Motherboard
Motherboard or also known as mainboard, system board or logic board (on Apple Computer) and sometimes abbreviated as mobo is the center of the main circuit board in an electronic system, such as a modern computer device. On this component will be placed (plugged in) other components such as main memory, processor, video adapter, sound adapter and others, so that a complete computer system is formed and can work.
Figure 3.12. Motherboard of a computer
3. CPU
Central Processing Unit (CPU), or often referred to as Processor, is a component in a digital computer that interprets instructions and processes data in a computer program. The CPU provides an important part of a digital system, namely the ability to be programmed. This component is a component that must be present in every computer device.
Figure 3.13. Central Processing Unit (CPU)
4. Main Memory
Main Memory or sometimes referred to as Primary Storage, or Internal Memory, is computer memory that can be directly accessed by the CPU without using the computer's input/output lines. This component is used to store data that is currently being actively used. Primary storage can consist of several types of storage such as main storage, cache memory, and special registers.
Figure 3.14. Various types of main memory
5. Expansion Cards
An expansion card is a printed circuit board (PCB) that can be plugged into an expansion slot on a computer's motherboard to increase the functionality of the computer. Examples of expansion cards include video adapter cards, audio adapter cards, network adapter cards, and others.
Figure 3.15. Installing the expansion card
6. Power Supply
A power supply or sometimes called a PSU (Power Supply Unit) is a device that supplies electrical energy or other types of energy to other components in a computer.
Figure 3.16. Power Supply Unit
7. Optical Disc Drive
Optical Disc is a secondary storage media that is shaped like a vinyl record, but in a smaller size. Data stored in Optical Disc is accessed when specific material on the Optical Disc is illuminated by a laser beam. There are two main types of Optical Discs, namely those based on CD (Compact Disc) and those based on DVD (Digital Versatile Disc). The device for reading, writing, or erasing is called an Optical Disc Drive.
Figure 3.17. CD-RW Drive, one example of an Optical Disc Drive
8. Secondary Storage (Hard Disk)
Secondary Storage is a device used to assist Primary Storage (main memory), especially to store data, programs, or information that will be used again. Unlike primary storage, data, programs and information on secondary storage will not be lost even if the computer is turned off, unless it is intentionally deleted. The most common secondary storage found in every computer is the Hard Disk. The hard disk will store data using magnetic materials in certain patterns that represent the data.
Figure 3.18. Hard Disk
9. Keyboard
Keyboard or key board, a device used to input text and characters into a computer. This device can also be used to control special functions on the computer. Figure 3.19 shows the layout of a common keyboard.
Figure 3.19. General schematic of a keyboard.
10. Mouse
The mouse, usually consisting of a pointing device, is used to detect the relative movement of two surfaces in two dimensions which is then displayed on the display. In addition, other functions are often added to the mouse, such as "wheels". In addition to detecting movement, the mouse also plays a role in executing commands by pressing the button on the mouse once (click) or twice in sequence (double click).
Figure 3.20. Various types of mouse
8. Software
Software is a computer program that functions as a means of interaction between users and hardware. Or it can also be interpreted as a 'translator' of commands run by computer users to be forwarded to or processed by hardware.
This computer program, its contents can be changed easily. On a computer, the software is loaded into RAM and then executed in the CPU. At the lowest level, the software contains machine language that is specific to a processor.
There are many software classification models, but in general software can be divided into three groups, namely:
1. System Software
System Software is software that is used to help run computer hardware and systems. The purpose of system software is to limit as much as possible the application programmer from the complexity of a computer, especially those related to direct memory and hardware access.
Included in this group are operating systems, hardware drivers, diagnostic software, windowing systems, utilities and others. From this group, the operating system is the most important software. This software works as an interface between the computer and the outside world. In the hardware section, the operating system will describe the hardware that exists or is connected to the computer. The operating system provides an interface to this hardware using a specific "driver" so that this device can be recognized and work as it should. A more detailed explanation of the operating system can be seen in Chapter 4.
Figure 3.21. Windows XP operating system desktop view
2. Programming Software
Programming Software is software that provides tools or functions that can help programmers in creating computer programs.
This software is very dependent on the programming language used. These tools include text editors, compilers, interpreters, linkers, debuggers and others. An Integrated Development Environment (IDE) combines these tools to make things easier for programmers. We will study this section a lot in this book.
3. Application Software
Application Software is software that is used to help humans perform certain tasks (sometimes not related to computers).
Types of application software include industrial automation software, business software, educational software, software, databases, and computer games. Some examples of application software can be seen in the following pictures.
Figure 3.22. Microsoft Word application software (City processing software)
Figure 3.23. Application software Winrar (File compression and extraction software)
Figure 3.24. PowerSim software application (Software for system simulation)
Figure 3.25. Application software Hysis (Software for factory design)
9. Summary
- Electronics is the science that studies low-current electrical devices that are operated by controlling the flow of electrons or electrically charged particles.
- The important elements in electrical theory are electric charge (Q), resistance (R), voltage (V) and current (I).
- Digital electronics are electronic systems that use digital signals and are composed of what are called logic gates.
- Logic gates are the building blocks of electronic hardware.
- There are three basic forms of truth tables and logic gates, namely AND, OR, and NOT. In addition, there are also derivative forms, namely NAND, NOR, and XOR.
- A computer is an electronic data processing tool that works and is controlled by a set of instructions (programs).
- A computer system is a collection of elements, namely humans, hardware and software, which interact with each other to achieve goals, namely obtaining useful information, ease of work, speed and other goals.
- There are three main components in a computer system, namely humans as users, hardware and software.
10. Practice Questions
- Explain the meaning of electronics.
- State the relationship between electric charge, resistance, voltage and current.
- Name the electronic components that you know.
- State the meaning of digital electronics.
- Describe the shapes of logic gates.
- Describe an example of a digital circuit.
- Name the components in a computer system.
- If one of the components of a computer system is unavailable, what will happen?