Published on March 8, 2014
Information Technology Concepts Presented by: Dr. Akhlas Ahmed Lecture # 01 Preston University Hardware: Input, Processing & Output
Hardware Components Central Processing Unit Primary Storage (main memory) Secondary Storage Input Devices Output Devices memory;
Hardware Components Control Unit Part of the CPU that sequentially accesses program instructions, decodes them, and coordinates the flow of data in and out of the ALU, the register, primary storage, and even secondary storage and various output devices. ALU Portion of the CPU that performs mathematical and logical comparisons.
Hardware Components Register High-speed storage area in the CPU used to temporarily hold small units of program instructions and data immediately before, during and after execution by the CPU. Primary Memory Part of the computer that program instructions and data. holds
Hardware Components in Action Step Step Step Step 1. 2. 3. 4. Fetch instruction Decode instruction Execute the instruction Store results
Hardware Components in Action Step 1: In the instruction phase, the computer’s control unit fetches the instruction to be executed from memory.
Hardware Components in Action Step 2: Then the instruction is decoded so the central processor can understand what is to be done. Step 1 & 2 are called the instruction phase, and the time is takes to perform this phase is called the INSTRUCTION TIME (I-time).
Hardware Components in Action Step 3: In the execution phase, the ALU does what it is instructed to do, making either an arithmetic computation or a logical comparison.
Hardware Components in Action Step 4: Then the results are stored in the registers or in memory Step 3 & 4 are called the execution phase. The time it takes to complete the execution phase is called the EXECUTION TIME (E-time).
Hardware Components in Action After both phases have been completed for one instruction, they are again performed for the second instruction, and so on. The instruction phase followed by the execution phase is called a MACHINE CYCLE.
Hardware Components in Action Some central processing units can speed up processing by using PIPELINING. Whereby the CPU gets one instruction, decodes another, and executes a third at the same time. The Pentium processor, for example, uses two execution unit pipelines. This gives the processing unit the ability to execute two instructions in a single machine cycle.
Processing & Memory Devices
Processing Characteristics and Functions Machine cycle time is measured in: Microseconds (1 millionth) for slower computers Nanoseconds (1 billionth) Picoseconds (1 trillionth) for faster ones. MIPS (Millions of Instructions Processed per Second)
Wordlength and Bus Line Width Data is moved within a computer system not in a continuous stream but in groups of bits. A Bit (BInary DigiT) 0 or 1. Therefore, another factor affecting overall system performance, particularly speed is the number of bits the CPU can process at any one time.
Wordlength and Bus Line Width This number of bits is called the Wordlength of the CPU. A CPU with a wordlength of 32 (called a 32-bit CPU) will process 32 bits of data in one machine cycle.
Wordlength and Bus Line Width Data is transferred from the CPU to other system components via Bus lines, the physical wiring that connects the computer system components. The number of bits a bus line can transfer at any time is known as bus line width. A bus line with a width of 32 will transfer 32 bits of data a time. Common wordlength and bus line widths are 32 and 64.
Memory Characteristics and Functions
Bill Gates made the famous remark… “640 K ought to be enough for anybody..” 1981…. Things have changed drastically! 2004 –PC with 512 MB of Main Memory was standard….
Types of Memory
Types of Memory Random Access Memory (RAM). Dynamic RAM (DRAM). Synchronous DRAM (SDRAM). SDRAM also has the advantage of a faster transfer speed between the microprocessor and the memory.
Types of Memory Read Only Memory (ROM) Programmable Read Only Memory (PROM). Commonly used in video games. Erasable Programmable Read Only Memory (EPROM). Commonly used with industrial robots and as a computer setup chip.
Read-Only Memory (ROM) Can be read but cannot be written to Nonvolatile BIOS Erasable ROM (EEPROM): Flash memory Can be written to and erased Secondary storage / Removable
Cache Memory Cache Memory is a type of high-speed memory that a processor can access more rapidly than main memory. Cache Memory works in conjunction with main memory.
Cache Memory A cache controller determines how often the data is used and transfer frequently used data to cache memory, then deletes the data when it goes out of use.
Multiprocessing A number of forms of Multiprocessing involves the simultaneous execution of two or more instructions at the same time. One form of multiprocessing involves coprocessors. A Coprocessor speeds processing by executing specific types of instructions while the CPU works on another processing activity. For example, math coprocessor chip can be used to speed mathematical calculations, and a graphics coprocessor chip decreases the time it takes to manipulate graphics.
Massively Parallel Processing Parallel Processing, a form of multiprocessing that speed processing by linking several processors to operate at the same time, or in parallel.
Massively Parallel Processing With Parallel Processing, a problem is divided into several parts. Each part is “solved” by a separate processor. The result from each processor are then assembled to get the final output.
Secondary Storage (Permanent Storage) Secondary storage devices that store larger amount of data, instructions, and information more permanently than allowed with main memory. Offers the advantages of nonvolatility, greater capacity, and greater economy
Access Methods Sequential: records must be retrieved in order Devices used are called sequential access storage devices (SASD) Direct: records can be retrieved in any order Devices used are called direct access storage devices (DASDs)
Devices Magnetic tapes Magnetic disks RAID (Redundant array of independent/inexpensive disks) Storage area networks (SAN) Optical disks Digital versatile disks (DVDs)
Devices Magnetic Disks are also coated with iron oxide; they can be thin steel platters (Hard Disk or Diskettes).
Hard Drives and Diskettes Hard Drives Several magnetic disks Read/write heads High storage capacity Diskettes Portable magnetic media
Types of Secondary Storage Magnetic Tapes and Disks, Optical Disks, and CDROMs, and DVD’s are used to store data for easy retrieval at a later date.
Devices Magnetic tapes (Common secondary storage medium, Mylar film coated with iron oxide with portions of the tape magnetized to represent bits.
Devices Magnetic Disks are also coated with iron oxide; they can be thin steel platters (Hard Disk or Diskettes).
Devices RAID (Redundant array of independent/inexpensive disks) is a method of storing data that generates extra bits of data from existing data, allowing the system to create “reconstruction map” so that if a hard drive fails, it can rebuild lost data. RAID sub-systems duplicate data on drives. This process is called DISK MIRRORING.
Devices SAN (Storage Area Network) uses computer servers, distributed storage devices, and network to tie everything together. To increase the speed of storing and retrieving data, fiber-optic channels are often used.
Devices - Optical Disk Storage Uses laser beam technology to read and write. Optical Disks a rigid disk of plastic onto which data is recorded by special lasers that physically burn pits in the disk. CD-ROM (Compact Disk Read Only Memory) a common form of optical Disks on which data, once it has been recorded, cannot be modified. CD-W (CD-Writeable) an optical disk that can written upon but only once. CD-RW (CD-Rewriteable) on optical disk that allows personal computer users to replace their diskettes with high-capacity CDs that can be written upon and edited over.
Devices Digital Versatile Disk Player (DVD) look like CDs but have a much greater storage capacity and can transfer data at a much faster rate.
Additional Devices and Media Memory cards (The PC memory card is like a portable hard disk that fits into PC Card slot. Flash memory (A silicon computer chip that, unlike RAM, is nonvolatile and keeps its memory when the power is shut off).
Additional Devices and Media Expendable Storage (Allow users to add additional storage capacity by simply plugging in a removable disk or cartridge. The disk can be used to back up hard disk data or to transfer large files to classmates.
Secondary Storage Comparison of methods of secondary storage
Input and Output Devices
Input Devices Personal computer input devices Keyboard (QWERTY) Virtual Laser Keyboard Virtual Laser Keyboard
Input Devices Pointing and Selecting Devices E.g., mouse, light pen, touch pad, touch screen, joystick, and eye-tracking device
Input Devices Scanning Devices (Entering Batch Data) Scanner (Used for repetitive information) a. b. Handheld scanner Flatbed scanner
Input Devices Audio - sound that has been digitized Voice Input Microphone Speech recognition Voice-to-text software
Input Devices Digital Video cameras (make it possible for people at distant locations to conduct videoconferences, thereby eliminating the need for expensive travel to attend physical meetings.
Input Devices Point of Sale (POS) Devices Credit/Debit Card Reader Biometric devices Read: Fingerprints Face geometry
Input Devices Magnetic Ink Character Recognition (MICR) Device
Other Scanning Technologies Text recognition software Optical character recognition (OCR) Optical mark recognition (OMR)
Output Devices Display monitors
Output Devices Display monitors CRT- Cathode Ray Tube The quality of Screen is often measured by the number of horizontal and vertical pixels used to create it. A larger number of pixels per square inch means a higher resolution, or clarity and sharpness of the image. For example, a screen with a 1024 x 768 resolution (786432 pixels) has a higher sharpness than one with 640 x 350 (224000 pixels).
Output Devices Display monitors The distance between one pixel on the screen and the next nearest pixel is known as DOT PITCH. The common range of dot pitch is from .25mm to .31mm. The smaller the number, the better the picture.
Output Devices Display monitors Monochrome (One of the three colors: Gray, green, or amber). CGA (Color Graphic Adaptor) was one of the first technologies to display color images on the screen. SVGA (Super Video Graphics Array) displays are standard, providing brilliant colors and higher resolutions.
Output Devices Display monitors LCD (Liquid Crystal Displays) Flat Panel Displays that’s use liquid crystal organic, oil-like material placed between two polarizers to form characters and graphic images on a backlit screen. Passive-Matrix displays, the CPU sends its signals to transistors around the borders of the screen, which control all the pixels in a given row or column. Active-Matrix display, each pixel is controlled by its own transistor attached in a thin film to the glass behind pixel.
Printers and Plotters
Output Devices Printers Daisy Wheel Plotters Dot Matrix 80 Columns 120 Columns Ink Jet Laser Jet Computer Output Microfilm (COM) Devices
Output Devices - Audio Output Sound card and speakers Sound card translates digits into sound Also used to capture sound Other audio output E.g., USB headphones
Computer System Types Supercomputers Typically use for Scientific applications, marketing , customer support, product development). Memory: 500+ GB
Computer System Types Mainframe Computers Typically use for large general purpose business & Government computing need to meet the goals. Memory: <100+ GB
Computer System Types Personal Computers Handheld fitting on desktop, typically use to improve personal productivity of a worker Memory: 512MB - 2GB
Computer System Types - Portable Computers Notebook computers Light weight Battery powered Limited expandability Docking stations
Computer System Types - Tablet PCs Type of notebook that accepts input from an electronic pen a. b. Slate model Convertible model
Computer System Types Small computers that can be carried in a pocket Niche in the portable computers market Handheld Computers Personal digital assistants (PDAs) Cell phones Most popular manufacturers RIM – Blackberry Palm – Treo
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