CIS 123 - Hardware

• List major hardware components of computers and explain their functions
• Classify computers into major categories, and identify their strengths and weaknesses
• Identify and evaluate key criteria for deciding which computers or related devices to purchase
• Discuss the possible health hazards of computer use

• input: keyboard, mouse, microphone
• processing: CPU, GPU
• storage: usually divided into primary and secondary storage (see descriptions in terminology section), RAM, ROM, hard drives, USB drives
• output: printer, monitor

• supercomputer: Supercomputers are very fast, have huge memory storage, and many CPUs. They often cost $1,000,000+, although much cheaper models not much larger than a powerful desktop computer are now available. They are used for highly specialized problems in science and research that rely on parallel processing. A cheaper alternative that is often used is to use a cluster of smaller computers to provide power similar to that of a supercomputer. A cluster is when many computers are connected together to work on a problem simultaneously, sharing the workload.
• mainframe: A mainframe can support large organizations, is often used for business functions, and can cost hundreds of thousands of dollars. They are general purpose computers. The processor speed may be similar to a powerful desktop or workstation, but mainframes are optimized for massive throughput. Throughput is the amount of work that the computer can get done.
• midrange: You don't see midrange computers much now. They were computers designed to support medium size organizations or large groups. Interestingly, midrange computers were sometimes used to handle input and output for supercomputers and mainframes to free up the larger machines for faster throughput.
• server: A server is the modern equivalent of a midrange computer. A server usually controls access to a particular resource, such as printing, disk storage, network access, a database, or some application. Other computers connect to the server to get access to whatever resource the server controls. Although servers are usually stacked in racks and stripped down to the essentials needed to perform their function, almost any computer can operate as a server if the correct software is installed on it.
• microcomputer: This has become an almost meaningless term. It was originally used to describe small, relatively inexpensive computers that used a microprocessor as its CPU. Since almost all computers now use a microprocessor, the term microcomputer has fallen out of use.
• desktop: A desktop is a non-portable computer that can range from a simple, entry-level systems to a powerful "workstation" able to process complex math and graphics quickly.
• notebook: A notebook is a small, portable computer which sacrifice some processing power and speed for the sake of portability and battery life.
• tablet: A tablet is a handheld mobile computer about the size of a hardcover textbook (or smaller) with a touch screen. They have limited processing power and often only run one application at a time, but they allow access to the Internet.
• PDA: A Personal Digital Assistant (PDA) is a small tablet-like computer with applications such as a contact list, note-taking, games, alarm, etc. that was usually controlled using a stylus in the old days. Higher end PDAs could do email and text messaging. PDAs have been mostly replaced by smartphones.
• stylus: A stylus is a pen-like pointing (and often writing) device used with PDAs and tablets before touch screens became common.
• smartphone: A smartphone is a phone with limited processing power and a screen large enough to do some web browsing, play some games, use email, and perform other applications designed for it.
• phablet: A phablet is a cross between a smartphone and a tablet, with a screen size that is also somewhere between the two.
• technology convergence: Technology convergence is building several technologies into a single device. This describes how designers make a device start performing tasks usually associated with a different type of device. This is currently happening a lot with cell phones, such as watching television shows and movies using a cellphone.

• CPU: (Central Processing Unit) accepts instructions and data, decodes and executes the instructions, and stores the processed data; a CPU includes a control unit and an ALU (among other parts)
• control unit: controls the operation of the CPU, deciding how instructions will be executed
• ALU: does basic arithmetic and logic operations such as addition, subtraction, AND, and OR operations
• GPU: (Graphics Processing Unit) a CPU for the graphical display
• multicore: a chip which contains more than one CPU that can operate at the same time
• multitasking: performing more than one task at a time
• parallel processing: more than one processor operating at the same time
• multithreading: running several parts of a single program at the same time
• machine cycle: fetch, decode, execute, store (this is a simplified overview)
• clock rate: a fast clock almost always drives (and synchronizes) the machine cycles
  • Hz: abbreviation for hertz, which is cycles per second
  • MHz: one million Hertz
  • GHz: one billion Hertz
• word: the standard data size used by the CPU (generally 32 or 64 bit currently)

• hardware: the physical components of a computer
• bus: communication lines (basically little wires) that carry instructions, data, and signals; generally measured by speed of transmission (in MHz) and number of bits transferred at the same time (bus width)
• motherboard: the main board of the computer to which all the components connect
• peripheral: devices located off the motherboard which are controlled by the computer
• MIPS: Million Instructions Per Second
• multiprocessor: a computer that supports having more than one processor operating at a time
• throughput: how many bits per second can travel across bus ("throughput" has other definitions also)

• volatile: refers to memory that loses its contents when power is off
• primary memory: (what the text calls internal memory) fast, in relatively short supply, expensive, usually volatile (RAM, ROM)
• secondary memory: (what the text calls external memory) slow, cheap, and often in relatively large supply when compared to primary memory; almost always non-volatile (disks, CDROM, flash memory sticks, etc.)
• RAM: (Random Access Memory) fast readable and writable main memory
• ROM: (Read Only Memory) like RAM, but can only be read (not written); non-volatile
• bit: binary digit, a 0 or a 1
• byte: a group of eight bits; can be used to store one character
  • KB: kilobyte, one thousand bytes (1,024 bytes of RAM/ROM)
  • MB: megabyte, one million bytes (1,048,576 bytes of RAM/ROM)
  • GB: gigabyte, one billion bytes (1,073,741,824 bytes of RAM/ROM)
  • TB: terabyte, one trillion bytes (~1,000,000,000,000 bytes)
  • PB: petabyte, one quadrillion bytes (~1,000,000,000,000,000 bytes)
  • EB: exabyte, one quintillion bytes (~1,000,000,000,000,000,000 bytes)
  • ZB: zettabyte, one sextillion bytes (~1,000,000,000,000,000,000,000 bytes)
  • YB: yottabyte, one octillion bytes (~1,000,000,000,000,000,000,000,000 bytes)
  • Note: digital computers are based on binary (base 2), so the number of bytes of RAM/ROM on the motherboard is usually a power of two.
• Note: The traditional British and European names for the numbers above differ. For example, you may see "billion" used in place of "trillion" in texts using traditional British or European terminology. Modern British, the United States, and Canada use the terms listed above.
• Note: In the early days, the terms listed above usually referred to powers of 2, so 1 MB referred to 1,048,576 bytes. Later, disk drive manufacturers started using the terms to refer to powers of 10, so in the case of a disk 1 MB meant 1,000,000 bytes. In 1998, a new standard is to use KB, MB, GB, etc. for powers of 10, and to use the following new abbreviations and prefixes for powers of 2:

  Abbrev.	Symbol	Amount
  Ki	Kibi-	1,024
  Mi	Mebi-	1,048,576
  Gi	Gibi-	1,073,741,824
  Ti	Tebi-	1,099,511,627,776
  Pi	Pebi-	1,125,899,906,842,624
  Ei	Exbi-	1,152,921,504,606,846,976
  Zi	Zebi-	1,180,591,620,717,411,303,424
  Yi	Yobi-	1,208,925,819,614,629,174,706,176

• nibble: half a byte (four bits); sometimes called a nybble

• I/O: Input and Output
• QWERTY: traditional keyboard layout
• Dvorak: a keyboard layout designed to increase typing speed
• RSI: Repetitive Stress Injury
• ergonomic: designed for safety and comfort
• mouse: input device used to control on-screen pointer; named due to relative size and wire resembling tail; modern mice are often wireless and optical
• trackball: similar to an upside-down old mouse where the mouse would be stationary, but the user would control the on-screen pointer by moving the ball in the mouse
• trackpad/touchpad: a small pad where finger movements across it can control the on-screen pointer
• touch screen: a monitor with a touch-sensitive surface which can be used for input
• source data input devices: read data directly from source
  • OCR: Optical Character Recognition
  • optical mark recognition: recognizes marks placed in specific spots (Scantron tests)
  • optical bar recognition: recognizes varying thicknesses of printed bars (bar codes)
  • QR code: Quick response code, a bar code with data printed in two dimensions (as a square)
  • optical character recognition: turns printed text into digital input by recognizing characters
  • MICR: Magnetic Ink Character Recognition; used on checks
  • magnetic strip readers: used on credit cards
• RFID: Radio Frequency IDentification (covered in previous chapter)
• imaging: directly scans and stores documents
• speech recognition: recognizes words in human speech and translates them into data or commands
• pixel: PIcture ELement; the name of the small dots that make up the display on a monitor
• CRT: Cathode Ray Tube (old, heavy, energy-sucking monitors seldom seen anymore)
• flat-panel: slim, efficient, light weight modern monitors
• LCD: Liquid Crystal Display, most common type of flat panel monitor
• resolution: number of pixels displayed on screen; also used for number of pixels per inch
• non-impact printer: imaging doesn't require striking the paper surface mechanically (laser, ink-jet, electrostatic, electro-thermal)
• impact printer: imaging requires striking paper surface mechanically (dot-matrix, band, daisy-wheel)
• DPI: Dots Per Inch; this is the density of picture elements on a page/screen and helps give an indication of how detailed/sharp the picture can be.

Note: Printer specifications should list the DPI and speed.

Questions:

• Which types of monitors are more reliable?
• Which type of monitor would you rather have when the power fails?
• Which type of monitor costs less to operate?
• Which types of printers are more reliable?
• Which type of printer would you rather have when the power fails?
• Which type of printer costs less to operate?
• Which type of printer do you want if you need fast printing?
• Which type of printer do you want if you need to print multi-part forms?
• Which type of printer do you want if you need color printing?

External storage is needed to quickly augment a computer system's original storage, to back up computer systems in case of failures, and to operate as shared and/or remote storage on networks.

• capacity: how much data can be held by a device
• access mode: specifies whether data must be accessed sequentially or any record can be reached directly
  • sequential access: storage organized as one record after another; access typically must start at the very beginning or end of the file and proceed in a forward direction
  • direct access: any record can be accessed directly without looking at all the records before it; also called random access
• DASD: Direct Access Storage Device
• USB: Universal Serial Bus; a common type of port used to connect peripherals, including Flash drives
• flash drives: memory devices that connect to a computer via a USB port (they use Flash memory)
• magnetic tape: sequential access, slow, cheap, very high capacity, medium-term reliability
• magnetic disks: direct access, fast, moderately priced, medium-term reliability, very high capacity available
• optical disks: direct access, medium speed, limited capacity, inexpensive, some types are read-only, longer-term reliability (CD, DVD)
• optical tape: rare, huge capacity
• Flash memory: relatively fast (although connection may be slow), stands up well to shock and vibration, small capacity, somewhat costly compared to hard drive
• SSD: Solid State Disk; a Flash memory replacement for a hard drive; can be 200 times faster than a hard drive
• DAS: Direct-Attached Storage; a storage device connected directly to a server
• NAS: Network-Attached Storage; a storage device that resides on the network and can be accessed as a network resource (very useful, but many products are defective by design - so watch out)
• SAN: Storage Area Network; a network devoted to data storage and transmission
• RAID: Redundant Array of Independent Disks; used to add performance and/or reliability to a storage system by using multiple disks together in ingenious ways; RAID has many levels/versions and may be implemented in hardware or software
• cloud storage: off-site network accessible data storage
• storage-as-a-service: cloud storage offered as a product

Considerations when evaluating storage media:

• use of stored data
• amount of stored data
• speed
• device size and portability
• cost
• reliability
• life expectancy

• device power: speed, memory size, storage capacity, etc.
• expansion slots: type and quantity of each
• ports: connectors on computer to which peripherals can be attached
• ports: type and quantity of each
• monitor type and resolution
• ergonomics: how the product designed for safety and comfort
• compatibility: ability to work with other hardware and software
• backward compatibility: ability to work with older hardware and software
• size of device
• weight of device
• portability of device
• quality of parts
• have standard parts been used to build device
• reliability of device
• length/coverage of warranty
• power consumption
• noise level
• cost
• scalability: ability to be expanded or upgraded to meet increased needs