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Hardware, Wake-up Process, Boot-Up, Operating System Control of Hardware Dr. Harold D. Camp IT 212 002 1 February 2007 PC Hardware Personal Computer Hardware A typical pc consists of a case or chassis in desktop or tower shape and the following parts: Motherboard or system board with slots for expansion cards and holding parts ** Central processing unit (CPU) Computer fan - used to cool down the CPU Random Access Memory (RAM) - for program execution and short term data storage, so the computer does not have to take the time to access the hard drive to find the file(s) it requires. More RAM will normally contribute to a faster PC. RAM is almost always removable as it sits in slots in the motherboard, attached with small clips. The RAM slots are normally located next to the CPU socket. Basic Input-Output System (BIOS) or Extensible Firmware Interface (EFI) in some newer computers Buses • PCI • PCI-E • USB • HyperTransport • CSI (expected in 2008) • AGP (being phased out) • VLB (outdated) • ISA (outdated) • EISA (outdated) Personal Computer Hardware Power supply - a case that holds a transformer, voltage control, and (usually) a cooling fan Storage controllers of IDE, SATA, SCSI or other type, that control hard disk, floppy disk, CD-ROM and other drives; the controllers sit directly on the motherboard (on-board) or on expansion cards Video display controller that produces the output for the computer display. This will either be built into the motherboard or attached in its own separate slot (PCI, PCI-E or AGP), requiring a Graphics Card. Computer bus controllers (parallel, serial, USB, FireWire) to connect the computer to external peripheral devices such as printers or scanners Some type of a removable media writer: • CD - the most common type of removable media, cheap but fragile. – CD-ROM Drive – CD Writer • DVD – DVD-ROM Drive – DVD Writer – DVD-RAM Drive • Floppy disk • Zip drive • USB flash drive AKA a Pen Drive • Tape drive - mainly for backup and long-term storage Personal Computer Hardware Internal storage - keeps data inside the computer for later use. • Hard disk - for medium-term storage of data. • Disk array controller Sound card - translates signals from the system board into analog voltage levels, and has terminals to plug in speakers. Networking - to connect the computer to the Internet and/or other computers • Modem - for dial-up connections • Network card - for DSL/Cable internet, and/or connecting to other computers. Other peripherals In addition, hardware can include external components of a computer system. The following are either standard or very common. Wheel Mouse Personal Computer Hardware Input or Input devices • Text input devices – Keyboard • Pointing devices – Mouse – Trackball • Gaming devices – Joystick – Gamepad – Game controller • Image, Video input devices – Image scanner – Webcam • Audio input devices – Microphone Output or Output devices • Image, Video output devices – Printer Peripheral device that produces a hard copy. (Inkjet, Laser) – Monitor Device that takes signals and displays them. (CRT, LCD) • Audio output devices – Speakers A device that converts analog audio signals into the equivalent air vibrations in order to make audible sound. – Headset A device similar in functionality to that of a regular telephone handset but is worn on the head to keep the hands free. Motherboard A typical computer is built with the microprocessor, main memory, and other basic components on the motherboard. Other components of the computer such as external storage, control circuits for video display and sound, and peripheral devices are typically attached to the motherboard via ribbon cables, other cables, and power connectors. A typical motherboard provides attachment points for one or more of the following: CPU, graphics card, sound card, hard disk controller, memory (RAM), and external peripheral devices. The connectors for external peripherals are nearly always color coded according to the PC 99 specification. Power Supply Power supplies, often referred to as "switching power supplies", use switcher technology to convert the AC input to lower DC voltages. The typical voltages supplied are: 3.3 volts 5 volts 12 volts The 3.3- and 5-volts are typically used by digital circuits, while the 12-volt is used to run motors in disk drives and fans. Case Cases usually come with room for a power supply unit, several expansion slots and expansion bays, wires for powering up a computer and some with built in I/O ports that must be connected to a motherboard. Motherboards are screwed to the bottom or the side of the case, its I/O ports being exposed on the back of the case. Usually the power supply unit is at the top of the case attached with several screws. The typical case has four 5.25" and three 3.5" expansion bays for devices such as hard drives, floppy disk drives and CD-ROMs. A power button and sometimes a reset button are usually located on the front. LED status lights for power and hard drive activity are often located near the power button and are powered from wires that are connected with the motherboard. Some cases come with status monitoring equipment such as case temperature or processor speed monitors. Disk Drive # Capacity, usually quoted in gigabytes. (older hard disks used to quote their smaller capacities in megabytes) # Physical size, usually quoted in inches: * Almost all hard disks today are of either the 3.5" or 2.5" varieties, used in desktops and laptops, respectively. CD ROM DVD ROM DVD (commonly "Digital Versatile Disc" or "Digital Video Disc") is an optical disc storage media format that can be used for data storage, including movies with high video and sound quality. DVDs resemble compact discs as their diameter is the same (120 mm (4.72 inches) or occasionally 80 mm (3.15 inches) in diameter), but they are encoded in a different format and at a much higher density. Tape Drives Instead of allowing random-access to data as hard disk drives do, tape drives only allow for sequential-access of data. A hard disk drive can move its read/write heads to any random part of the disk platters in a very short amount of time, but a tape drive must spend a considerable amount of time winding tape between reels to read any one particular piece of data. As a result, tape drives have very slow average seek times. Despite the slow seek time, tapes drives can stream data to tape very quickly. For example, modern LTO drives can reach continuous data transfer rates of up to 80 MB/s, which is as fast as most 10,000 rpm hard disks. Removable Disks The disk format itself had no more capacity than the more popular (and cheaper) 5¼-inch floppies. Each side of a double-density disk held 180 KB for a total of 360 KB per disk, and 720 KB for quad-density disks. Unlike 5¼- inch or 3½-inch disks, the 3-inch disks were designed to be reversible and sported two independent write-protect switches. It was also more reliable thanks to its hard casing. USB Flash Drives currently are sold from 32 megabytes up to 64 gigabytes IDE Controller Built into the motherboard, two connections provide for ribbon cables that send signals controlling disk drives AGP Expansion Slots The Accelerated Graphics Port (also called Advanced Graphics Port) is a high-speed point-to-point channel for attaching a graphics card to a computer's motherboard, primarily to assist in the acceleration of 3D computer graphics. Some motherboards have been built with multiple independent AGP slots. AGP is currently being phased out in favor of PCI Express. PCI Express Superseded By: (2004) Width: 32 bits Number of 1 device/slot Devices: Speed: up to 2133 MB/s Style: Parallel Hotplugging? no External? no PCI Expansion Slot The Peripheral Component Interconnect, or PCI Standard (in practice almost always shortened to PCI) specifies a computer bus for attaching peripheral devices to a computer motherboard. These devices can take any one of the following forms: An integrated circuit fitted onto the motherboard itself, called a planar device in the PCI specification. An expansion card that fits in sockets. Video Card A video card, (also referred to as a graphics accelerator card, display adapter and numerous other terms), is an item of personal computer hardware whose function is to generate and output images to a display. The term is usually used to refer to a separate, dedicated expansion card that is plugged into a slot on the computer's motherboard, as opposed to a graphics controller integrated into the motherboard chipset. Sound Card A sound card is a computer expansion card that can input and output sound under control of computer programs. Typical uses of sound cards include providing the audio component for multimedia applications such as music composition, editing video or audio, presentation/education, and entertainment (games). Many computers have sound capabilities built in, while others require these expansion cards if audio capability is desired. Random Access Memory (RAM) Random access memory (usually known by its acronym, RAM) is a type of data store used in computers. It takes the form of integrated circuits that allow the stored data to be accessed in any order — that is, at random and without the physical movement of the storage medium or a physical reading head. The word "random" refers to the fact that any piece of data can be returned quickly, and in a constant time, regardless of its physical location and whether or not it is related to the previous piece of data. This contrasts with storage mechanisms such as tapes, magnetic disks and optical disks, which rely on the physical movement of the recording medium or a reading head. In these devices, the movement takes longer than the data transfer, and the retrieval time varies depending on the physical location of the next item. Clock In electronics and especially synchronous digital circuits, a clock signal is a signal used to coordinate the actions of two or more circuits. A clock signal oscillates between a high and a low state, normally with a 50% duty cycle, and is usually a square wave. Circuits using the clock signal for synchronization may become active at either the rising or falling edge, or both of the clock signal. Most integrated circuits (ICs) of sufficient complexity utilize a clock signal in order to synchronize different parts of the circuit and to account for propagation delays. As ICs become more complex, the problem of supplying accurate and synchronized clocks to all the circuits becomes increasingly difficult. The preeminent example of such complex chips is the microprocessor, the central component of modern computers. Basic Input/Output System BIOS, in computing, stands for Basic Input/Output System also incorrectly known as Basic Integrated Operating System. BIOS refers to the firmware code run by a computer when first powered on. The primary function of the BIOS is to prepare the machine so other software programs stored on various media (such as hard drives, floppies, and CDs) can load, execute, and assume control of the computer. This process is known as booting up. BIOS can also be said to be a coded program embedded on a chip that recognises and controls various devices that make up the computer. The term BIOS is specific to personal computer vendors. Among other classes of computers, the generic terms boot monitor, boot loader or boot ROM are commonly used. Microprocessor A microprocessor (sometimes abbreviated µP) is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). The microprocessor was born by reducing the word size of the CPU from 32 bits to 4 bits, so that the transistors of its logic circuits would fit onto a single part. One or more microprocessors typically serve as the CPU in a computer system, embedded system, or handheld device. Heat Sink and Fan A heat sink is an environment or object that absorbs and dissipates heat from another object using thermal contact (in either direct or radiant contact). Universal Serial Bus (USB) Universal Serial Bus (USB) is a serial bus standard to interface devices. It was originally designed for computers, but its popularity has prompted it to also become commonplace on video game consoles, PDAs, portable DVD and media players, cellphones; and even devices such as televisions, home stereo equipment (e.g., digital audio players), car stereos and portable memory devices. The radio spectrum based USB implementation is known as Wireless USB. Keyboard A computer keyboard is a peripheral partially modeled after the typewriter keyboard. Keyboards are designed for the input of text and characters and also to control the operation of a computer Network Connector An electrical connector is a device for joining electrical circuits together. The connection may be temporary, as for portable equipment, or may require a tool for assembly and removal, or may be a permanent electrical joint between two wires or devices. There are hundreds of types of electrical connectors. In computing, an electrical connector can also be known as a physical interface. Parallel Port A parallel port is a type of socket found on personal computers for interfacing with various peripherals. It is also known as a printer port or Centronics] port. The IEEE 1284 standard defines the bi- directional version of the port. For the most part, the USB interface has replaced the Centronics-style parallel port — as of 2006, most modern printers are connected through a USB connection, and often don't even have a parallel port connection. On many modern computers, the parallel port is omitted for cost savings, and is considered to be a legacy port. In laptops, access to a parallel port is still commonly available through docking stations. Serial Port In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time (contrast parallel port). Throughout most of the history of personal computers, data transfer through serial ports connected the computer to devices such as terminals or modems. Mice, keyboards, and other peripheral devices also connected in this way. While such interfaces as Ethernet, FireWire, and USB all send data as a serial stream, the term "serial port" usually identifies hardware more or less compliant to the RS- 232 standard, intended to interface with a modem or with a similar communication device. For the most part, the USB interface has replaced the serial port — as of 2006, most modern computers are connected to devices through a USB connection, and often don't even have a serial port connection. The serial port is omitted for cost savings, and is considered to be a legacy port. Modem A modem (from modulate and demodulate) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Faster modems are used by Internet users every day, notably cable modems and ADSL modems. Operating System An operating system (OS) is a computer program that manages the hardware and software resources of a computer. At the foundation of all system software, the OS performs basic tasks such as controlling and allocating memory, prioritizing system requests, controlling input and output devices, facilitating networking, and managing files. It also may provide a graphical user interface for higher level functions. It forms a platform for other software. Services • Process Management • Disk and File Management • Internal/External Security • Networking • Graphical User Interfaces (GUI) • Device Drivers Microsoft Windows OS The Microsoft Windows family of operating systems originated as a graphical layer on top of the older MS-DOS environment for the IBM PC. Modern versions are based on the newer Windows NT core that first took shape in OS/2 and borrowed from VMS. Windows runs on 32-bit and 64-bit Intel and AMD processors, although earlier versions also ran on the DEC Alpha, MIPS, Fairchild (later Intergraph) Clipper and PowerPC architectures (some work was done to port it to the SPARC architecture). As of 2006, Windows held a near-monopoly of around 94% of the worldwide desktop market share, although some predict this to dwindle due to the increased interest in open source operating systems. It is also used on low-end and mid-range servers, supporting applications such as web servers and database servers. In recent years, Microsoft has spent significant marketing and R&D money to demonstrate that Windows is capable of running any enterprise application which has resulted in consistent price/performance records (see the TPC) and significant acceptance in the enterprise market at the cost of existing Unix based system market share. Other Operating Systems Macintosh Operating System Apple deliberately downplayed the existence of the operating system in the early years of the Macintosh to help make the machine appear more user-friendly and to distance it from other operating systems such as MS-DOS, which were portrayed as arcane and technically challenging. Apple wanted Macintosh to be portrayed as a computer "for the rest of us". The term "Mac OS" did not really exist until it was officially used during the mid-1990s. The term has since been applied to all versions of the Mac system software as a handy way to refer to it when discussing it in context with other operating systems. Unix/Linix Unix systems run on a wide variety of machine architectures. They are used heavily as server systems in business, as well as workstations in academic and engineering environments. Free software Unix variants, such as Linux and BSD, are popular but have not reached significant market share in the desktop market. They are used in the desktop market as well, for example Ubuntu, but mostly by hobbyists. How a Disk Boot Wakes Up a PC • A personal computer can't do anything useful unless it's running an operating system • A basic type of software, such as Microsoft Windows, that acts as a supervisor for all the applications, games, or other programs you use. • The operating system sets the rules for using memory, drives, and other parts of the computer. • Before a PC can run an operating system, it needs some way to load the operating system from disk to random access memory (RAM). • The way to do this is with the bootstrap, or simply to boot—a small amount of code that's a permanent part of the PC. Power On Self Test • Turn on your PC, electricity warms up the components that send, receive, and memorize bits and bytes of data rushing through the system. One stream of electricity follows the same permanently programmed path it has followed each time the computer came to life. • The path takes current to the CPU, or microprocessor. The electrical signal clears leftover data from the chip's internal memory registers and places a specific hexadecimal number, F000, into one of the CPU's digital note pads, called the program counter. • Whatever number is in the program counter tells the CPU the memory address of the next instruction. In this case, it's the first instruction, located on a flash memory chip on the computer's motherboard. This chip holds a few small programsthat determine how your computer works. All together, they're called the BIOS. • Now the BIOS awakens the computer's components, performing the power-on self-test (POST) to make sure the computer is functioning properly. Boot • BIOS checks a small, 64-byte chuck of RAM that is kept alive by a battery even when the computer is off that contains the official record of which components are installed in your system. • The BIOS and CPU check to make sure they're working right. • The BIOS loads device drivers and interrupt handlers into memory the for the basic hardware in the system, such as the keyboard, mouse, hard drive, and floppy drive. • To be sure all the PC's operations function in a synchronized, orderly fashion, the CPU also checks the system's clock, which is responsible for pacing signals. • The CPU sends signals over the system bus to be sure all of the components are functioning. • The POST tests the memory contained on the display adapter and the video signals that control the display. At this point, you'll first see something appear on your PC's monitor. • The BIOS checks to see if it's engaged in a cold boot, meaning the computer had been turned off, or if it's a warm boot, or reboot, by checking the value at memory address 0000:0472. • For a cold boot the BIOS runs a series of tests to ensure that the RAM chips are functioning properly. • The tests write data to each chip, and then read it and compare what they read with the data sent • The POST sends signals over specific paths on the bus to the internal floppy, optical, and hard disk drives, and listens for a response to determine which drives are available. After the POST • A typical Windows XP boot sequence starts with the MBR loading the bootstrap loader for the OS, which will tell the computer everything it needs to know about its memory and how to use it, how the files are stored, and put up the boot menu. • In many computers, the boot menu is not shown unless the user asks for it. The bootloader then launches a program that collects more information about the hardware installed in it and then loads the core operating system files. • Then, it reads the registry from which it gathers the information necessary to communicate with different components, and then load the necessary programs (drivers) to communicate with devices attached to the computer. After the POST Once this is done, the bootloader loads the program that shows the welcome or logon screen. Once the user logs in, the computer loads the shell (Explorer), which shows the desktop to the user. At this point, the OS is loaded and the computer is ready for use. A typical boot takes about a minute, with the BIOS boot sequence taking about 10-15 seconds. The term booting is short for bootstrapping. The word bootstrapping is derived from the phrase "pulling himself up by his bootstraps", which has its origins in the tall stories narrated by Baron Munchhausen, a German nobleman in the eighteenth century. How an Operating System Controls PC Hardware OPERATING systems originally were developed to handle one of the most complex input/output operations: communicating with a variety of disk drives. This is evidenced by the names given to early operating systems, which often contained the acronym DOS, for disk operating system. Eventually, the operating system quickly evolved into an all- encompassing bridge between your PC and the software you run on it. How Hardware and Software Work Together • Choose a command, like save • Word processor tells OS to save • OS knows how to control hardware • OS does infrastructure work • Program does your work How Hardware and Software Work Together Device Drivers • A device driver, or a software driver is a specific type of computer software, typically developed to allow interaction with hardware devices. • This usually constitutes an interface for communicating with the device, through the specific computer bus or communications subsystem that the hardware is connected to, • Driver provides commands to and receives data from the device, and on the other end, the requisite interfaces to the operating system and software applications. • Often called simply a driver, it is a specialized hardware-dependent computer program, which is operating system specific, that enables another program, typically an operating system or applications software package, to interact transparently with the given device. • Usually provides the requisite interrupt handling required for any necessary asynchronous time-dependent hardware interfacing needs. Types of Hardware Drivers Because of the diversity of modern hardware and operating systems, many ways exist in which drivers can be used. Drivers are used for interfacing with: • Printers • Video adapters • Network cards • Sound cards • Local buses of various sorts - in particular, for bus mastering on modern systems • Low-bandwidth I/O buses of various sorts (for pointing devices such as mice, keyboards, USB, etc.) • computer storage devices such as hard disk, CD-ROM and floppy disk buses (ATA, SATA, SCSI) • Implementing support for different file systems • Implementing support for image scanners and digital cameras Enhanced Integrated Drive Electronics (EIDE) • A disk drive device driver • An enhanced version of the IDE drive interface • Expands the maximum disk size from 504 MB to 8.4 GB, • More than doubles the maximum data transfer rate, • And supports up to four drives per PC (as opposed to two in IDE systems). • Now that hard disks with capacities of 1 GB or more are commonplace in PCs, • EIDE is an extremely popular interface. • EIDE's primary competitor is SCSI-2, which also supports large hard disks and high transfer rates. Enabling Disk Access • Disk controller translates instructions from the BIOS and Disk Drivers into electrical signals • Move drive’s read/write head to proper location • Create or read magnetic signals that represent data HW Interrupts 1. Press a key, an electrical signal identifies what key you pressed, to the keyboard controller. 2. The keyboard interrupt arrives on one of 16 interrupt request (IRQ) lines. Seven of the IRQs monitor specific components, such as the keyboard controller. 3. The controller relays a signal to the interrupt controller that determines which of the 256 possible kinds of interrupts request the CPU's attention. 4. More than one expansion card on the PCI Peripheral Component Interconnect (PCI) and PCI-Express slots can use the same IRQ because the requests are managed by the Plug 'n' Play function. 5. The interrupt controller sends a signal called the INTR, used for normal interrupt signals. 6. The CPU puts whatever it was doing on hold. 7. A CPU uses one of two methods from computing: polling and interrupts. 8. The CPU checks to find out what key you pressed. The CPU checks a section of memory called the interrupt descriptor table (IDT). Specifically, the CPU performs the instructions at one of the IDT's locations associated with the key. 9. When the interrupt software completes its job, it sends an instruction to the CPU. That tells the CPU it is free to return to whatever it was doing before it was interrupted. How Plug and Plan Works With Plug and Play under Microsoft Windows Server 2003, you can connect a hardware device to your system and leave the job of configuring and starting the device to the operating system. If the device and drivers are not designed to take advantage of Plug and Play, Windows Server 2003 will not be able to automatically configure and start the device. Plug and Play in Windows Server 2003 supports a wide range of devices. In Windows Server 2003, Plug and Play support is optimized for computers that include an Advanced Configuration and Power Interface (ACPI) BIOS. ACPI devices are defined by the Advanced Configuration and Power Interface (ACPI) Specification, a hardware and software interface specification that combines and enhances the Plug and Play and Advanced Power Management (APM) standards. ACPI devices include low-level system devices such as batteries and thermal zones. Plug and Play detection runs with the logon process and relies on system firmware, hardware, device drivers, and operating system features to detect and enumerate new devices. ACPI firmware provides enhanced features, such as hardware resource sharing. When Plug and Play components are coordinated, Windows Server 2003 can detect new devices, allocate system resources, and install or request drivers with minimal user intervention. Plug and Play Architecture Plug and Plan Driver Installation When a hardware device is connected — as when you plug a USB camera into a USB port — Plug and Play Manager goes through the following steps to install the device. • After receiving an insertion interrupt, Plug and Play Manager checks what hardware resources the device needs • memory ranges, I/O ranges, and DMA channels. Plug and Play Manager then assigns those resources. • Plug and Play Manager checks the hardware identification number of the device. • Plug and Play Manager then checks the hard drive, floppy drives, CD-ROM drives, and Windows Update for drivers that match the number of the device. • If multiple drivers are found, Plug and Play Manager chooses the driver that is the best match by looking for the closest hardware ID or compatible ID match, driver signatures, and other driver features. • Plug and Play Manager then installs the best-match driver and the operating system starts the device. Homework Prepare a single page paper addressing each of the following questions: • What is the registry? • What does it do? Due Next Week • How does it work? • Why does a PC require a registry?
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