Software And Hardware

Hardware

The physical components of a computer are called hardware. Pieces of hardware may be categorized according to the functions each performs: input, process, output, and storage. As you recall, inside the computer, all data are represented by the binary digits (bits) 1 (one) and 0 (zero). To translate data into 1s and 0s is to digitize.

Input Devices 

Input devices function to take data that people understand and translate those data into a form that the computer can process. Input devices may be divided into two categories: keyboards and direct-entry devices. Direct-entry devices include pointing devices, scanning devices, smart and optical cards, speech and vision input, touch screens, sensors, and human-biology input devices. The pointing device with which you are most familiar is the mouse, which you can use to position the insertion point on the screen, or make a choice from a menu. Other pointing devices are variations of the mouse. Light pens, digitizing tablets, and pen-based systems allow you to use a pen or stylus to enter data. The marks you make or letters you write are digitized. Most scanning devices digitize data by shining a light on an image and measuring the reflection. Bar-code scanners read the universal product codes; optical mark recognition devices can recognize a mark on paper; optical character recognition devices can recognize letters. Special scanning equipment called magnetic ink character recognition (MICR) is used by banks to read the numbers at the bottoms of checks. You are familiar with fax machines, which scan images, digitize them, and send them over telecommunication lines. Some scanning devices, called image scanners, scan and digitize whole pages of text and graphics. One scanning device of particular interest to those with impaired eyesight is the Kurzweil scanner—hardware and software—which scans printed text and reads it aloud to the user. Radio frequency identification (RFID) tags (input devices) are now used to identify anything from the family dog to the sponge the surgeon left in your body, by sending out radio waves. One medical insurance company is conducting a two-year trial with chronically ill patients who will have an RFID the size of a grain of rice implanted. The RFID will contain their medical histories. It transmits 30 feet without the person’s knowledge. In 2006, one U.S. company implanted chips in two of its employees “as a way of controlling access to a room where it holds security video footage for government agencies and police.” Several different kinds of cards are used as input devices: your automated teller machine (ATM) card or charge card contains a small amount of data in the magnetic stripe. A smart card can hold more data and contains a microprocessor. Smart cards have been used as debit cards. Several states now use smart cards as driver’s licenses. The card includes a biometric identifier and may include other personal information as well. Privacy advocates fear that there is so much information on the cards that they can become a target for identity thieves. An optical card holds about two thousand pages. The optical card may be used to hold your entire medical history, including test results and X-rays. If you are hospitalized in an emergency, the card—small enough to carry in your wallet—would make this information immediately available. Vision input systems are currently being developed and refined. A computer uses a camera to digitize images and stores them. The computer “sees” by having the camera take a picture of an object. The digitized image of this object is then compared to images in storage. This technology can be used in adaptive devices, such as in glasses that help Alzheimer’s patients. The glasses include a database of names and faces; a camera sees a face, and if it “recognizes” the face, it gives the wearer the name of the subject. Speech input systems allow you to talk to your computer, and the computer processes the words as data and commands. A speech-recognition system contains a dictionary of digital patterns of words. You say a word and the speech-recognition system digitizes the word and compares the word to the words in its dictionary. If it recognizes the word, the command is executed. There are speech dictation packages tailored to specific professions. A system geared toward medicine would include an extensive vocabulary of digitized medical terms and would allow the creation of patient records and medical reports. This system can be used as an input device by physicians who, in turn, can dictate notes, even while, for example, operating. Speech recognition is also especially beneficial as an enabling technology, allowing those who do not have the use of their hands to use computers. In English, many phrases and words sound the same, for example, hyphenate and -8 (hyphen eight). Speech-recognition software allows mistakes such as these to be corrected by talking. The newest speech-recognition software does not need training and gets “smarter” as you use it. It looks at context to get homophones (to, too, two) correct. Of particular interest to health professionals are input devices called sensors. A sensor is a device that collects data directly from the environment and sends those data to a computer. Sensors are used to collect patient information for clinical monitoring systems, including physiological, arrhythmia, pulmonary, and obstetrical/ neonatal systems. In critical care units, monitoring systems make nurses aware of any change in a patient’s condition immediately. They detect the smallest change in temperature, blood pressure, respiration, or any other physiological measurement. The newest kinds of input devices are called human-biology input devices. They allow you to use your body as an input device. They include biometrics, which are being used in security systems to protect data from unauthorized access. Biometrics identify people by their body parts. Biometrics include fingerprints, hand prints, face recognition, and iris scans. Once thought to be almost 100 percent accurate, biometric identification systems are now recognized as far from perfect. Line-of-sight input allows the user to look at a keyboard displayed on a screen and indicate the character selected by looking at it. Implanted chips have allowed locked-in stroke patients (a syndrome caused by stroke where a person cannot respond, although he or she knows what is going on) to communicate with a computer by focusing brain waves (brain wave input); this is experimental; research is continuing. 

Processing Hardware and Memory

Once data are digitized, they are processed. Processing hardware is the brain of the computer. Located on the main circuit board (or motherboard), the processor or system unit contains the central processing unit (CPU) and memory. The CPU has two parts: the arithmetic-logic unit, which performs arithmetic operations and logical operations of comparing; and the control unit, which directs the operation of the computer in accordance with the program’s instructions. The CPU works closely with memory. The instructions of the program being executed must be in memory for processing to take place. Memory is also located on chips on the main circuit board. The part of memory where current work is temporarily stored during processing is called random-access memory (RAM). It is temporary and volatile. The other part of memory is called read-only memory (ROM) or firmware; it contains basic start-up instructions, which are burned into a chip at the factory; you cannot change the contents of ROM. Many computers have open architecture that allows you to add devices. The system board contains expansion slots, into which you can plug expansion boards for additional hardware. The board has sockets on the outside, called ports. You can plug a cable from your new device into the port. The significance of open architecture is the fact that it enables you to add any hardware and software interfaces to your existing computer system. This means you can not only expand the memory of your computer but also add devices that make your computer more amenable to uses in medicine. Expansion boards also allow the use of virtual reality simulators, which help in teaching certain procedures.

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