Lecture 1 - Computing Components.pdf

Lecture 1 COMPUTING COMPONENTS: Processors, Memory, the Cloud, and More Computing Components At some point, you might have to open the case on a desktop or access panels on a laptop to replace or install a new electronic component. For this reason, you should be familiar with the electronic compone...

Lecture 1 COMPUTING COMPONENTS: Processors, Memory, the Cloud, and More Computing Components At some point, you might have to open the case on a desktop or access panels on a laptop to replace or install a new electronic component. For this reason, you should be familiar with the electronic components inside the case. Guess the word: Guess the word: Guess the word: The Motherboard The motherboard, sometimes called a system board, is the main circuit board of the computer. Many electronic components, such as the processor and memory, attach to the motherboard; others are built into it. The Motherboard The Motherboard On personal computers, the circuitry for the processor, memory, and other components reside on a computer chip(s). A computer chip is a small piece of semiconducting material, usually silicon, and etched in it are integrated circuits. An integrated circuit contains many microscopic pathways capable of carrying electrical current. Each integrated circuit can contain millions of elements such as resistors, capacitors, and transistors. A transistor, for example, can act as an electronic switch that opens or closes the circuit for electrical charges. Today’s computer chips contain millions or billions of transistors. Processors The processor, also called the central processing unit (CPU), interprets and carries out the basic instructions that operate a computer. The processor significantly impacts overall computing power and manages most of a computer’s operations. On larger computers, such as mainframes and supercomputers, the various functions performed by the processor extend over many separate chips and often multiple circuit boards. On a personal computer, all functions of the processor usually are on a single chip. Some computer and chip manufacturers use the term microprocessor to refer to a personal computer processor chip. Processors Most processor chip manufacturers now offer multi-core processors. A processor core, or simply core, contains the circuitry necessary to execute instructions. The operating system views each processor core as a separate processor. A multi-core processor is a single chip with two or more separate processor cores. Multi-core processors are used in all sizes of computers. Are multi-core processors better than single-core processors? Each processor core on a multi-core processor generally runs at a slower speed than a single-core processor, but multi-core processors typically increase overall performance. For example, although a dual-core processor does not double the processing speed of a single-core processor, it can approach those speeds. The performance increase is especially noticeable when users are running multiple programs simultaneously, such as antivirus software, spyware remover, email program, Internet messaging, media player, and photo editing software. Multi-core processors also are more energy efficient than separate multiple processors, requiring lower levels of power consumption and emitting less heat inside the case. Processors Processors contain a Control Unit and an Arithmetic Logic Unit (ALU). These two components work together to perform processing operations. When a user runs an application, for example, its instructions transfer from a storage device to memory. Data needed by programs and applications enters memory from either an input device or a storage device. The control unit interprets and executes instructions in memory, and the arithmetic logic unit performs calculations on the data in memory. Resulting information is stored in memory, from which it can be sent to an output device or a storage device for future access, as needed. The Control Unit The control unit is the component of the processor that directs and coordinates most of the operations in the computer. That is, it interprets each instruction issued by a program or an application and then initiates the appropriate action to carry out the instruction. Types of internal components that the control unit directs include the arithmetic logic unit, registers, and buses. The Arithmetic Logic Unit The Arithmetic Logic Unit (ALU), another component of the processor, performs arithmetic, comparison, and other operations. Arithmetic operations include basic calculations, such as addition, subtraction, multiplication, and division. Comparison operations involve comparing one data item with another to determine whether the first item is greater than, equal to, or less than the other item. Depending on the result of the comparison, different actions may occur. For example, to determine if an employee should receive overtime pay, software instructs the ALU to compare the “number of hours an employee worked during the week” with the “regular time hours allowed (e.g., 40 hours)”. If the hours worked exceed 40, for example, software instructs the ALU to perform calculations that compute the overtime wage. Machine Cycle For every instruction, a processor repeats a set of four basic operations, which comprise a machine cycle: 1. Fetching is the process of obtaining a program or an application instruction or data item from memory. 2. Decoding refers to the process of translating the instruction into signals the computer can execute. 3. Executing is the process of carrying out the commands. 4. Storing, in this context, means writing the result to memory (not to a storage medium). Machine Cycle In some computers, the processor fetches, decodes, executes, and stores only one instruction at a time. With others, the processor fetches a second instruction before the first instruction completes its machine cycle, resulting in faster processing. Some use multiple processors simultaneously to increase processing times. Registers A processor contains small, high-speed storage locations, called registers, that temporarily hold data and instructions. Registers are part of the processor, not part of memory or a permanent storage device. Processors have many different types of registers, each with a specific storage function. Register functions include storing the location from where an instruction was fetched, storing an instruction while the control unit decodes it, storing data while the ALU calculates it, and storing the results of a calculation. The System Clock The processor relies on a small quartz crystal circuit called the system clock to control the timing of all computer operations. Just as your heart beats at a regular rate to keep your body functioning, the system clock generates regular electronic pulses, or ticks, that set the operating pace of components of the system unit. Each tick equates to a clock cycle. Processors today typically are superscalar, which means they can execute more than one instruction per clock cycle. The System Clock The pace of the system clock, called the clock speed, is measured by the number of ticks per second. Current personal computer processors have clock speeds in the gigahertz range. Giga is a prefix that stands for billion, and a hertz is one cycle per second. Thus, one gigahertz (GHz) equals one billion ticks of the system clock per second. A computer that operates at 3 GHz has 3 billion (giga) clock cycles in one second (hertz). The System Clock The faster the clock speed, the more instructions the processor can execute per second. The speed of the system clock is just one factor that influences a computer’s performance. Other factors include the type of processor chip, amount of cache, memory access time, bus width, and bus clock speed. Personal Computer and Mobile Device Processors The leading manufacturers of personal computer processor chips are Intel and AMD. AMD manufactures Intel-compatible processors, which have an internal design similar to Intel processors, perform the same functions, and can be as powerful, but often are less expensive. These manufacturers often identify their processor chips by a model name or model number. Personal Computer and Mobile Device Processors Processor chips include technologies to improve processing performance (for example, to improve performance of media and 3-D graphics). Some also include technology to track computer hardware and software, diagnose and resolve computer problems, and secure computers from outside threats. Processors for mobile computers also include technology to optimize and extend battery life and integrate wireless capabilities. Smaller mobile devices often use more compact processors that consume less power, yet offer high performance. Processor Cooling Processor chips for laptops, desktops, and servers can generate heat, which could cause the chip to malfunction or fail. Heat sinks, liquid cooling technologies, and cooling mats often are used to help further dissipate processor heat. Heat Sink A heat sink is a small ceramic or metal component with fins on its surface that absorbs and disperses heat produced by electrical components, such as a processor. Many heat sinks have fans to help distribute air dissipated by the heat sink. Some heat sinks are packaged as part of a processor chip. Others are installed on the top or the side of the chip Liquid Cooling Some computers use liquid cooling technology to reduce the temperature of a processor. Liquid cooling technology uses a continuous flow of fluid(s), such as water and glycol, in a process that transfers the heated fluid away from the processor to a radiator-type grill, which cools the liquid, and then returns the cooled fluid to the processor. Cooling Pad Laptop users often use a cooling pad to help further reduce the heat generated by their computer. A cooling pad rests below a laptop and protects the computer from overheating and also the user’s lap from excessive heat. Some cooling pads contain a small fan to transfer heat away from the laptop. Instead of using power, other pads absorb heat through a conductive material inside the pad. Data Representation To understand how a computer processes data, you should know how a computer represents data. People communicate through speech by combining words into sentences. Human speech is analog because it uses continuous (wave form) signals that vary in strength and quality. Most computers are digital. They recognize only two discrete states: on and off. This is because computers are electronic devices powered by electricity, which also has only two states: on and off. Bits and Bytes The two digits, 0 and 1, easily can represent these two states. The digit 0 represents the electronic state of off (absence of an electronic charge). The digit 1 represents the electronic state of on (presence of an electronic charge). When people count, they use the 10 digits in the decimal system (0 through 9). The computer, by contrast, uses a binary system because it recognizes only two states. The binary system is a number system that has just two unique digits, 0 and 1, called bits. A bit (short for binary digit) is the smallest unit of data the computer can process. By itself, a bit is not very informative. Bits and Bytes When 8 bits are grouped together as a unit, they form a byte. A byte provides enough different combinations of 0s and 1s to represent 256 different characters. These characters include numbers, uppercase and lowercase letters of the alphabet, punctuation marks, and other keyboard symbols, such as an asterisk (*), ampersand (&), and dollar sign ($). Coding Schemes The combinations of 0s and 1s that represent uppercase and lowercase letters, numbers, and special symbols are defined by patterns called a coding scheme. Coding schemes map a set of alphanumeric characters (letters and numbers) and special symbols to a sequence of numeric values that a computer can process. ASCII (pronounced ASK-ee), which stands for American Standard Code for Information Interchange, is the most widely used coding scheme to represent a set of characters. In the ASCII coding scheme, for example, the alphabetic character E is represented as 01000101; the symbolic character * is represented as 00101010; the numeric character 6 is represented as 00110110. Coding Schemes When you press a key on a keyboard, a chip in the keyboard converts the key’s electronic signal into a special code, called a scan code, that is sent to the electronic circuitry in the computer. Then, the electronic circuitry in the computer converts the scan code into its ASCII binary form and stores it as a byte value in its memory for processing. When processing is finished, the computer converts the byte into a human-recognizable number, letter of the alphabet, or special character that is displayed on a screen or is printed. All of these conversions take place so quickly that you do not realize they are occurring. Four Pictures, One Word Memory Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processing the data (information). Memory usually consists of one or more chips on the motherboard or some other circuit board in the computer. Memory Memory stores three basic categories of items: 1. The operating system and other programs that control or maintain the computer and its devices 2. Applications that carry out a specific task, such as word processing 3. The data being processed by the applications and the resulting information This role of memory to store both data and programs is known as the stored program concept. Bytes and Addressable Memory A byte (character) is the basic storage unit in memory. When an application’s instructions and data are transferred to memory from storage devices, the instructions and data exist as bytes. Each byte resides temporarily in a location in memory that has an address. Simply put, an address is a unique number that identifies the location of a byte in memory. To access data or instructions in memory, the computer references the addresses that contain bytes of data. Common Sizes for Memory Manufacturers state the size of memory in terms of the number of bytes it has available for storage. Common sizes for memory are in the gigabyte and terabyte range. A gigabyte (GB) equals approximately 1 billion bytes. A terabyte (TB) is equal to approximately 1 trillion bytes. Types of Memory Computers and mobile devices contain two types of memory: volatile and nonvolatile. When the computer’s power is turned off, volatile memory loses its contents. Nonvolatile memory, by contrast, does not lose its contents when power is removed from the computer. Thus, volatile memory is temporary and nonvolatile memory is permanent. RAM is the most common type of volatile memory. Examples of nonvolatile memory include ROM, flash memory, and CMOS. 1. RAM Users typically are referring to RAM when discussing computer and mobile device memory. RAM (random access memory), also called main memory, consists of memory chips that can be read from and written to by the processor and other devices. When you turn on power to a computer or mobile device, certain operating system files (such as the files that determine how the desktop or home screen appears) load into RAM from a storage device such as a hard drive. These files remain in RAM as long as the computer or mobile device has continuous power. As additional applications and data are requested, they also load into RAM from storage. Types of RAM Two common types of RAM are: Dynamic RAM (DRAM pronounced DEE-ram) chips must be reenergized constantly or they lose their contents. Many variations of DRAM chips exist, most of which are faster than the basic DRAM. Static RAM (SRAM pronounced ESS-ram) chips are faster and more reliable than any variation of DRAM chips. These chips do not have to be reenergized as often as DRAM chips; hence, the term, static. SRAM chips, however, are much more expensive than DRAM chips. Special applications, such as cache, use SRAM chips. Common DRAM variations Memory Modules RAM chips usually reside on a memory module, which is a small circuit board. Memory slots on the motherboard hold memory modules. Two types of memory modules are SIMMs and DIMMs. SIMM DIMM Single Inline Memory Module Dual Inline Memory Module Supports 32-bit channel for data transfer Supports 64-bit channel for data transfer. Storage space of about 4 MB to 64 MB Storage space of about 32 MB & higher An old technology Replacement for SIMMs 2. Cache Most of today’s computers improve their processing times with cache (pronounced cash), which is a temporary storage area. Two common types of cache are memory cache and disk cache. Memory cache Memory cache helps speed the processes of the computer because it stores frequently used instructions and data. Most personal computers today have two types of memory cache: Level 1 (L1) cache and Level 2 (L2) cache. Some also have Level 3 (L3) cache. L1 cache is built directly on the processor chip. L1 cache usually has a very small capacity. L2 cache is slightly slower than L1 cache but has a much larger capacity. Current processors include advanced transfer cache (ATC), a type of L2 cache built directly on the processor chip. Processors that use ATC perform at much faster rates than those that do not use it. L3 cache is a cache on the motherboard that is separate from the processor chip. L3 cache exists only on computers that use L2 advanced transfer cache. Memory cache When the processor needs an instruction or data, it searches memory in this order: L1 cache, then L2 cache, then L3 cache (if it exists), then RAM If the instruction or data is not found in memory, then it must search a slower speed storage medium, such as a hard drive or optical disc. 3. ROM Read-only memory (ROM pronounced rahm) refers to memory chips storing permanent data and instructions. The data on most ROM chips cannot be modified — hence, the name read-only. ROM is nonvolatile, which means its contents are not lost when power is removed from the computer. ROM In addition to computers and mobile devices, many peripheral devices contain ROM chips. For example, ROM chips in printers contain data for fonts. Manufacturers of ROM chips often record data, instructions, or information on the chips when they manufacture the chips. 4. Flash Memory Flash memory is a type of nonvolatile memory that can be erased electronically and rewritten. Most computers use flash memory to hold their start-up instructions because it allows the computer to update its contents easily. For example, when the computer changes from standard time to daylight savings time, the contents of a flash memory chip (and the real-time clock chip) change to reflect the new time. Flash Memory Flash memory chips also store data and programs on many mobile devices and peripheral devices, such as smartphones, portable media players, printers, digital cameras, automotive devices, and digital voice recorders. When you enter names and addresses in a smartphone, for example, a flash memory chip stores the data. Some portable media players store music on flash memory chips; others store music on tiny hard drives or memory cards. Memory cards contain flash memory on a removable device instead of a chip. 5. CMOS Some RAM chips, flash memory chips, and other memory chips use complementary metal-oxide semiconductor (CMOS pronounced SEE-moss) technology because it provides high speeds and consumes little power. CMOS technology uses battery power to retain information even when the power to the computer is off. Battery-backed CMOS memory chips, for example, can keep the calendar, date, and time current even when the computer is off. The flash memory chips that store a computer’s start-up information often use CMOS technology. Memory Access Times Access time is the amount of time it takes the processor to read data, instructions, and information from memory. A computer’s access time directly affects how fast the computer processes data. For example, accessing data in memory can be more than 200,000 times faster than accessing data on a hard disk because of the mechanical motion of the hard disk. Today’s manufacturers use a variety of terminology to state access times. Some use fractions of a second, which for memory occurs in nanoseconds. A nanosecond (abbreviated ns) is one billionth of a second. A nanosecond is extremely fast (Figure 6-15). In fact, electricity travels about one foot in a nanosecond. Access Time Abbreviation  D 2 +P Adapters Although the circuitry in many of today’s computers integrates all the necessary functionality, some require additional capabilities in the form of adapters. Desktops and servers use adapter cards; mobile computers use USB adapters. Adapter Cards An adapter card, sometimes called an expansion card or adapter board, is a circuit board that enhances the functions of a component of a desktop or server system unit and/or provides connections to peripheral devices. An expansion slot is a socket on a desktop or server motherboard that can hold an adapter card. Two popular adapter cards are sound cards and video cards. A sound card enhances the sound-generating capabilities of a Personal computer by allowing sound to be input through a microphone and output through external speakers or headphones. A video card, also called a graphics card, converts computer output into a video signal that travels through a cable to the monitor, which displays an image on the screen. Adapter Cards Today’s computers support Plug and Play technology, which means the computer automatically can recognize peripheral devices as you install them. Plug and Play support means you can plug in a device and then immediately begin using it. Adapter Cards USB Adapters Because of their smaller size, mobile computers typically do not have expansion slots. Instead, users can purchase a USB adapter, which is a dongle that plugs into a USB port, enhances functions of a mobile computer, and/or provides connections to peripheral devices. USB adapters can be used to add memory, communications, multimedia, security, and storage capabilities to mobile computers. A USB flash drive is a common USB adapter that provides computers and mobile devices with additional storage capability as long as it is plugged in. USB Adapters Unlike adapter cards that require you to open the system unit and install the card on the motherboard, you can change a removable flash memory device without having to open the system unit or restart the computer. This feature, called hot plugging, allows you to insert and remove a device while the computer is running (be sure, though, to stop or eject the device before removing it). Buses Each channel, called a bus, allows the various devices both inside and attached to the system unit to communicate with one another. Just as vehicles travel on a highway to move from one destination to another, bits travel on a bus. Buses are used to transfer bits from input devices to memory, from memory to the processor, from the processor to memory, and from memory to output or storage devices. Buses consist of a data bus and an address bus. The data bus is used to transfer actual data, and the address bus is used to transfer information about where the data should reside in memory. Bus Width The size of a bus, called the bus width, determines the number of bits that the computer can transmit at one time. For example, a 32-bit bus can transmit 32 bits (4 bytes) at a time. On a 64-bit bus, bits transmit from one location to another 64 bits (8 bytes) at a time. The larger the number of bits handled by the bus, the faster the computer transfers data. Types of Buses A computer has a system bus, possibly a backside bus, and an expansion bus. A system bus, also called the front side bus (FSB), is part of the motherboard and connects the processor to main memory. A backside bus (BSB) connects the processor to cache. An expansion bus allows the processor to communicate with peripheral devices. Power Supply and Batteries Many personal computers plug in standard wall outlets, which supply an alternating current (AC) of 115 to 120 volts. This type of power is unsuitable for use with a computer or mobile device, which requires a direct current (DC) ranging from 5 to more than 15 volts. The power supply or laptop AC adapter converts the wall outlet AC power into DC power. Different motherboards and computers require different wattages on the power supply. If a power supply is not providing the necessary power, the computer will not function properly. Power Supply and Batteries Built into the power supply is a fan that keeps the power supply cool. Some users install more fans to help dissipate heat generated by the components of the computer. Power Supply and Batteries Mobile computers and devices can run using either a power supply or batteries. The batteries typically are rechargeable lithium-ion batteries. Some mobile devices and computers, such as some ultrathin laptops, do not have removable batteries. Summary Computing Components I. The Motherboard II. Processors Cores/Multicores Control Unit & ALU Machine Cycle Registers System Clock PC & Mobile Processors Processor Cooling (Heat Sink, Liquid Cooling, Cooling Pad) Summary III. Data Representation Bits and Bytes Coding Schemes IV. Memory Bytes and Addressable Memory Common Sizes for Memory Types of Memory RAM (Types & variations of RAM, modules) Cache (L1, L2, L3) ROM Flash Memory CMOS Memory Access Times Summary V. Adapters Sound, Video and other types of adapter cards Plug and Play USB adapters VI. Buses Bus Width Types of Buses VII. Power Supplies and Batteries