Information Systems Technician Training Series

Transcription

1 NONRESIDENT TRAINING COURSE August 1997 Information Systems Technician Training Series Modue 2 Computer Systems NAVEDTRA NOTICE Any reference within this modue to Radioman or the former Radioman rating shoud be changed to Information Systems Technician and the Information Systems Technician (IT) rating. The subject matter presented reates to the occupationa standards for the IT rating. DISTRIBUTION STATEMENT A: Approved for pubic reease; distribution is unimited.

2 Athough the words he, him, and his are used sparingy in this course to enhance communication, they are not intended to be gender driven or to affront or discriminate against anyone. DISTRIBUTION STATEMENT A: Approved for pubic reease; distribution is unimited.

3 PREFACE By enroing in this sef-study course, you have demonstrated a desire to improve yoursef and the Navy. Remember, however, this sef-study course is ony one part of the tota Navy training program. Practica experience, schoos, seected reading, and your desire to succeed are aso necessary to successfuy round out a fuy meaningfu training program. COURSE OVERVIEW: In competing this nonresident training course, you wi demonstrate a knowedge of the subject matter by correcty answering questions on the foowing subjects: Computer Hardware Startup, Computer Center Operations, and Data Management. THE COURSE: This sef-study course is organized into subject matter areas, each containing earning objectives to hep you determine what you shoud earn aong with text and iustrations to hep you understand the information. The subject matter refects day-to-day requirements and experiences of personne in the rating or ski area. It aso refects guidance provided by Enisted Community Managers (ECMs) and other senior personne, technica references, instructions, etc., and either the occupationa or nava standards, which are isted in the Manua of Navy Enisted Manpower Personne Cassifications and Occupationa Standards, NAVPERS THE QUESTIONS: The questions that appear in this course are designed to hep you understand the materia in the text. VALUE: In competing this course, you wi improve your miitary and professiona knowedge. Importanty, it can aso hep you study for the Navy-wide advancement in rate examination. If you are studying and discover a reference in the text to another pubication for further information, ook it up Edition Prepared by DPC(SW) Water Shugar, Jr. and RMCS(SW/AW) Deborah Hearn. Pubished by NAVAL EDUCATION AND TRAINING PROFESSIONAL DEVELOPMENT AND TECHNOLOGY CENTER NAVSUP Logistics Tracking Number 0504-LP i

4 Saior s Creed I am a United States Saior. I wi support and defend the Constitution of the United States of America and I wi obey the orders of those appointed over me. I represent the fighting spirit of the Navy and those who have gone before me to defend freedom and democracy around the word. I proudy serve my country s Navy combat team with honor, courage and commitment. I am committed to exceence and the fair treatment of a. ii

5 CONTENTS CHAPTER PAGE 1. Computer Hardware Startup Computer Center Operations Data Management APPENDIX I. Gossary AI-1 II. Gossary of Acronyms and Abbreviations AII-1 III. References Used to Deveop the TRAMAN AIII-1 INDEX INDEX-1 NONRESIDENT TRAINING COURSE foows the index iii

6 CREDITS Trademark Credits Microsoft is a registered trademark of Microsoft Corporation. WordPerfect is a registered trademark of WordPerfect Corporation. iv

7 SUMMARY OF THE RADIOMAN TRAINING SERIES MODULE 1 Administration and Security This modue covers Radioman duties reating to administering AIS and communication systems. Procedures and guidance for handing of cassified information, messages, COMSEC materia and equipment, and AIS requirements are discussed. MODULE 2 Computer Systems This modue covers computer hardware startup, incuding periphera operations and system modification. Other topics discussed incude computer center operations, media ibrary functions, system operations, and troubeshooting techniques. Data fie processes, memory requirements, and database management are aso covered. MODULE 3 Network Communications This modue covers network administration, LAN hardware, and network troubeshooting. Reated areas discussed are network configuration and operations, components and connections, and communication ines and nodes. MODULE 4 Communications Hardware This modue covers various types of communications equipment, incuding sateites and antennas. Subjects discussed incude hardware setup procedures, COMSEC equipment requirements, distress communications equipment, troubeshooting equipment, sateite theory, and antenna seection and positioning. MODULE 5 Communications Center Operations This modue covers center operations, incuding transmit message systems, voice communications, center administration, quaity contro, and circuit setup/restorations. Guideines for setting EMCON and HERO conditions and cryptosecurity requirements are aso discussed.

8 INSTRUCTIONS FOR TAKING THE COURSE ASSIGNMENTS The text pages that you are to study are isted at the beginning of each assignment. Study these pages carefuy before attempting to answer the questions. Pay cose attention to tabes and iustrations and read the earning objectives. The earning objectives state what you shoud be abe to do after studying the materia. Answering the questions correcty heps you accompish the objectives. SELECTING YOUR ANSWERS Read each question carefuy, then seect the BEST answer. You may refer freey to the text. The answers must be the resut of your own work and decisions. You are prohibited from referring to or copying the answers of others and from giving answers to anyone ese taking the course. SUBMITTING YOUR ASSIGNMENTS To have your assignments graded, you must be enroed in the course with the Nonresident Training Course Administration Branch at the Nava Education and Training Professiona Deveopment and Technoogy Center (NETPDTC). Foowing enroment, there are two ways of having your assignments graded: (1) use the Internet to submit your assignments as you compete them, or (2) send a the assignments at one time by mai to NETPDTC. Grading on the Internet: Internet grading are: Advantages to you may submit your answers as soon as you compete an assignment, and you get your resuts faster; usuay by the next working day (approximatey 24 hours). In addition to receiving grade resuts for each assignment, you wi receive course competion confirmation once you have competed a the assignments. To submit your assignment answers via the Internet, go to: Grading by Mai: When you submit answer sheets by mai, send a of your assignments at one time. Do NOT submit individua answer sheets for grading. Mai a of your assignments in an enveope, which you either provide yoursef or obtain from your nearest Educationa Services Officer (ESO). Submit answer sheets to: COMMANDING OFFICER NETPDTC N SAUFLEY FIELD ROAD PENSACOLA FL Answer Sheets: A courses incude one scannabe answer sheet for each assignment. These answer sheets are preprinted with your SSN, name, assignment number, and course number. Expanations for competing the answer sheets are on the answer sheet. Do not use answer sheet reproductions: Use ony the origina answer sheets that we provide reproductions wi not work with our scanning equipment and cannot be processed. Foow the instructions for marking your answers on the answer sheet. Be sure that bocks 1, 2, and 3 are fied in correcty. This information is necessary for your course to be propery processed and for you to receive credit for your work. COMPLETION TIME Courses must be competed within 12 months from the date of enroment. This incudes time required to resubmit faied assignments. vi

9 PASS/FAIL ASSIGNMENT PROCEDURES If your overa course score is 3.2 or higher, you wi pass the course and wi not be required to resubmit assignments. Once your assignments have been graded you wi receive course competion confirmation. If you receive ess than a 3.2 on any assignment and your overa course score is beow 3.2, you wi be given the opportunity to resubmit faied assignments. You may resubmit faied assignments ony once. Internet students wi receive notification when they have faied an assignment--they may then resubmit faied assignments on the web site. Internet students may view and print resuts for faied assignments from the web site. Students who submit by mai wi receive a faiing resut etter and a new answer sheet for resubmission of each faied assignment. COMPLETION CONFIRMATION After successfuy competing this course, you wi receive a etter of competion. ERRATA Errata are used to correct minor errors or deete obsoete information in a course. Errata may aso be used to provide instructions to the student. If a course has an errata, it wi be incuded as the first page(s) after the front cover. Errata for a courses can be accessed and viewed/downoaded at: For subject matter questions: E-mai: n311.products@cnet.navy.mi Phone: Comm: (850) DSN: FAX: (850) (Do not fax answer sheets.) Address: COMMANDING OFFICER NETPDTC N SAUFLEY FIELD ROAD PENSACOLA FL For enroment, shipping, grading, or competion etter questions E-mai: feetservices@cnet.navy.mi Phone: To Free: Comm: (850) /1181/1859 DSN: /1181/1859 FAX: (850) (Do not fax answer sheets.) Address: COMMANDING OFFICER NETPDTC N SAUFLEY FIELD ROAD PENSACOLA FL NAVAL RESERVE RETIREMENT CREDIT If you are a member of the Nava Reserve, you may earn retirement points for successfuy competing this course, if authorized under current directives governing retirement of Nava Reserve personne. For Nava Reserve retirement, this course is evauated at 5 points. (Refer to Administrative Procedures for Nava Reservists on Inactive Duty, BUPERSINST , for more information about retirement points.) STUDENT FEEDBACK QUESTIONS We vaue your suggestions, questions, and criticisms on our courses. If you woud ike to communicate with us regarding this course, we encourage you, if possibe, to use e-mai. If you write or fax, pease use a copy of the Student Comment form that foows this page. vii

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11 Student Comments Course Tite: Information Systems Technician Training Series Modue 2 Computer Systems NAVEDTRA: Date: We need some information about you: Rate/Rank and Name: SSN: Command/Unit Street Address: City: State/FPO: Zip Your comments, suggestions, etc.: Privacy Act Statement: Under authority of Tite 5, USC 301, information regarding your miitary status is requested in processing your comments and in preparing a repy. This information wi not be divuged without written authorization to anyone other than those within DOD for officia use in determining performance. NETPDTC 1550/41 (Rev 4-00 ix

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13 CHAPTER 1 COMPUTER HARDWARE STARTUP LEARNING OBJECTIVES Upon competing this chapter, you shoud be abe to do the foowing: Describe the different components of a computer system. Describe how to startup a computer system. Describe how to set parameters for operation and how to perform and interpret diagnostic tests. Expain what is invoved in inspecting components, running system checks and troubeshooting error conditions. Expain how to perform computer interface changes, CMOS changes and configuration changes. Describe how to inspect, repair and insta cabes. Expain how to insta computer equipment and prepare computers for shipment. We receive information in many different forms, from our eyes, ears, nose, mouth, and even sensory nerves. Our brains receive and accept this information, work with it in some form or fashion, and then store it away somewhere in the back of our minds (memories) for future use. If what we are processing at the time requires immediate attention, our minds direct us to respond with words or actions. The computer s brain (the centra processing unit) is designed to do basicay the same thing. That is, it receives information (input data), works with this information (processes data), and transmits this information (output data) to some form of output media. This is often shown graphicay as: Computers do nothing more than what we instruct them to do. They simpy foow a set of internay stored instructions (caed a program or software) we provide and process the data we feed into them. The design of fifth-generation computers is such that they wi actuay earn from previous experiences and appy what they have earned. This is caed artificia inteigence. Artificia inteigence computers manipuate data more efficienty, with parae processing, and understand written and spoken human anguage. Utimatey, we may have a computer simiar to the human brain. COMPUTER SYSTEM HARDWARE A eectronic digita computer systems consist of a centra processing unit (CPU) and one or more periphera devices for inputting and outputting data and 1-1

14 programs. Figure 1-1 shows the CPU and the types of periphera (input and output [I/O]) devices you wi find in a computer system. The devices are interconnected by eectrica cabes thru a bus to aow communications between them. The CPU communicates with the periphera devices through input/output (I/O) channes. The brain of a computer system is the centra processing unit, which we refer to as the CPU. THE CPU IS THE COMPUTER. It receives the data transferred to it from one of the various I/O devices. It processes the data and transfers the intermediate or fina resuts to an I/O device for storage or distribution. The CPU executes stored programs and does a the processing and manipuating of data. It contains the circuits that contro and perform the execution of instructions using various types of memories. The I/O devices simpy aid the computer by providing and receiving data and programs. In this section, you earn about the contro unit, the arithmetic-ogic unit, primary storage, secondary storage, periphera devices, I/O channes, and modems. Figure 1-1. Units/devices of a computer system. 1-2

15 CONTROL UNIT The contro unit maintains order within the computer system and directs the fow of traffic (operations) and data. The fow of contro is indicated by the dotted arrows on figure 1-1. The contro unit seects one program statement at a time from the program storage area, interprets the statement, and sends the appropriate eectronic impuses to the arithmetic-ogic unit and storage section to cause them to carry out the instruction. The contro unit does not perform the actua processing operations on the data. Specificay, the contro unit manages the operations of the CPU, be it a singe-chip microprocessor or a fi-size mainframe. Like a traffic director, it decides when to start and stop (contro and timing), what to do (program instructions), where to keep information (memory), and with what devices to communicate (I/O). It contros the fow of a data entering and eaving the computer. It accompishes this by communicating or interfacing with the arithmetic-ogic unit, memory, and I/O areas. It provides the computer with the abiity to function under program contro. Depending on the design of the computer, the CPU can aso have the capabiity to function under manua contro through man/machine interfacing. The contro unit consists of severa basic ogicay defined areas. These ogicay defined areas work cosey with each other. Timing in a computer reguates the fow of signas that contro the operation of the computer. The instruction and contro portion makes up the decision-making and memory-type functions. Addressing is the process of ocating the operand (specific information) for a given operation. An interrupt is a break in the norma fow of operation of a computer (e.g., CTRL + ALT + DEL). Contro memory is a random-access memory (RAM) consisting of addressabe storage registers. Cache memory is a sma, high-speed RAM buffer ocated between the CPU and main memory; it can increase the speed of the PC. Read-ony memory (ROM) are chips with a set of software instructions suppied by the manufacturer buit into them that enabes the computer to perform its I/O operations. The contro unit is aso capabe of shutting down the computer when the power suppy detects abnorma conditions. ARITHMETIC-LOGIC UNIT The arithmetic-ogic unit (ALU) performs a arithmetic operations (addition, subtraction, mutipication, and division) and ogic operations. Logic operations test various conditions encountered during processing and aow for different actions to be taken based on the resuts. The data required to perform the arithmetic and ogica functions are inputs from the designated CPU registers and operands. The ALU reies on basic items to perform its operations. These incude number systems, data routing circuits (adders/subtracters), timing, instructions, operands, and registers. Figure 1-2 shows a representative bock diagram of an ALU of a microcomputer. PRIMARY STORAGE (MAIN MEMORY) The primary storage section (aso caed interna storage, main storage, main memory, or just memory) serves four purposes:. To hod data transferred from an I/O device to the input storage area, where it remains unti the computer is ready to process it. This is indicated by the soid arrow on figure To hod both the data being processed and the intermediate resuts of the arithmetic-ogic operations. This is a working storage area within the storage section. It is sometimes referred to as a scratch pad memory.. To hod the processing resuts in an output storage area for transfer to an I/O device. Figure 1-2. Representative bock diagram of an ALU. 1-3

16 To hod the program statements transferred from an I/O device. This area is caed the program storage area. Pease note that the four areas (input, working, output, and program storage) are NOT fixed in size or ocation, but rather are determined by each individua program s requirements. About now, you re probaby wondering how the contro unit is abe to find these stored instructions and data items. To understand this, picture memory as a wa of post office boxes in a post office. Each box has a different number (address) and represents a specific storage ocation in memory, as shown in figure 1-3. Like the mai in a post office box, the contents of a storage ocation can change, but the number on the post office box or memory address does not change. In this manner, a particuar program instruction or data item that is hed in primary storage can be ocated by knowing its address. It is the responsibiity of the programmer to assign descriptive names to these data items. This enabes the computer program and the computer to keep track of the storage ocation address of each data item. Primary storage can be cassified by its physica or functiona characteristics. Memory Types by Physica Characteristics Primary storage devices may be cassified according to the type of magnetic or eectronic principe they use to store data. Some of the more common types are magnetic core storage, semiconductor storage, and bubbe storage. MAGNETIC CORE STORAGE. Magnetic core storage, athough not used as much as it used to be, provides an easy way to show the genera concepts of memories, incuding integrated semiconductor and bubbe types of memories. Magnetic core storage is made up of tiny doughnut-shaped rings made of ferrite (iron), which are strung on a grid of very thin wires. Because computers store data in binary form (covered in chapter 3), a two-state device is needed to represent the two binary digits (bits), 0 for OFF and 1 for ON. In core storage, each ferrite ring can represent a 0 bit or a 1 bit, depending on its magnetic state. If magnetized in one direction, it represents a 1 bit, and if magnetized in the opposite direction, it represents a 0 bit. These cores are magnetized by sending an eectric current through the wires on which the core is strung. It is this direction of current that determines the state of each core. Look at figure 1-4. Since the cores store data in the form of magnetic charges, core storage retains the data even when the power is off. This is caed nonvoatie storage. An exampe of nonvoatie storage is ROM. However, the process of reading from core is destructive. This means the data must be eectronicay regenerated after being read. SEMICONDUCTOR STORAGE (SILICON CHIP). Semiconductor memory has hundreds of thousands of tiny eectronic circuits etched on a siicon chip. Each eectronic circuit, caed a bit ce, can represent a 0 bit or a 1 bit, depending on the current fow in that bit ce. An OFF state represents a 0 bit, and an ON state represents a 1 bit. Another name you hear used for semiconductor memory chips is integrated circuits (ICs). (See figure 1-5.) Technoogica deveopments have enabed even more circuits to be put on a singe chip, resuting in arge-scae integration (LSI) and very-arge-scae integration (VLSI). Figure 1-3. Memory ocations. Figure 1-4. Two-state principe of magnetic storage. 1-4

17 RAM. When you turn the power to the computer off, a the stored data is ost. Aso, when there is a power faiure and you do not have a backup power suppy, a the stored data is ost. As mentioned, this is not the case with magnetic core storage. With core storage, the data is retained even when there is a power faiure or breakdown, since data is stored in cores in the form of magnetic charges, not eectric current. Figure 1-5. Semiconductor memory chip exposed. Some of the advantages of semiconductor storage are fast interna processing speeds, high reiabiity, ow power consumption, high density (many circuits), and ow cost. However, a drawback to this type of storage is that it must have a constant power source. The term for this is voatie storage. An exampe of voatie storage is BUBBLE STORAGE. Bubbe memory is one of the newer storage technoogies, generay used in aptops. It consists of a very thin crysta made of semiconductor materia. The moecues of the crysta act as tiny magnets. Data is stored by changing the poarity of these moecues, caed magnetic domains. The magnetic domains can be switched in an opposite direction by passing a current through a contro circuit imprinted on top of the crysta. Like magnetic core storage, bubbe memory is nonvoatie. The data is retained even when the power is turned off or there is a power faiure. Unike magnetic storage, reading from bubbe memory is nondestructive. The data does not have to be regenerated; it is sti present after being read. If we were to view these magnetic domains under a microscope, they woud ook ike tiny bubbes; hence, the name, bubbe memory. (See figure 1-6.) Memory Types by Function Functionay, we can cassify memory by its operationa features: random-access memory (RAM), Figure 1-6. Bubbe memory. 1-5

18 read-ony memory (ROM), programmabe read-ony memory (PROM), and erasabe programmabe readony memory (EPROM). RANDOM-ACCESS MEMORY (RAM). RAM, aso caed read/write memory, is ike a chakboard. You can write notes, read them, and erase them when you no onger need them. In the computer, RAM is the working memory. Data can be read (retrieved) from or written (stored) into RAM just by giving the computer the address of the RAM ocation where the data is stored or is to be stored. When the data is no onger needed, you can simpy write over it. This aows you to use the storage again for something ese. Core, semiconductor, and bubbe storage have randomaccess memory (RAM) capabiities. READ-ONLY MEMORY (ROM). In most computers, it is usefu to have often used instructions, such as those used to bootstrap (initia system oad) the computer or other speciaized programs, permanenty stored inside the computer. The memory that enabes us to do this without the programs and data being ost even when the computer is powered down is read-ony memory (ROM). Ony the computer manufacturer can insta these programs into ROM, and, once instaed, they cannot be changed. Consequenty, you cannot put any of your own data or programs into ROM. Many compex functions, such as routines to cacuate square root, transators for high-eve programming anguages, and operating systems, can be stored into ROM. Because the instructions are permanenty stored, they are quicky performed with accuracy. Aso, your computer faciity can order programs designed for its needs and have them permanenty instaed into ROM by the manufacturer. To describe these permanenty instaed programs, the term microprogram, or firmware, is used. PROGRAMMABLE READ-ONLY MEMORY (PROM). Your computer faciity can aso buy programmabe read-ony memory (PROM) aready programmed by the manufacturer or in a bank state. Using a bank PROM and a device designed to write (burn) a program into PROM, you can enter any program into the memory. However, you cannot make any changes to the program once it has been written into PROM. But, PROM does provide fexibiity not avaiabe with ROM. Of course, you must be sure the program is error free before it is written into PROM. ERASABLE PROGRAMMABLE READ- ONLY MEMORY (EPROM). The erasabe programmabe read-ony memory (EPROM) was deveoped to overcome the drawback of PROM. Your faciity can buy bank EPROMs from the manufacturer, and you can write programs deveoped at your command/activity using a specia device. The big difference with EPROM is that you can erase it if and when the need arises. The data and programs can be retrieved many times. If you want to reprogram memory, you first erase the EPROM with a burst of utravioet ight. This not ony enabes you to reprogram when requirements change, but aso, you can erase and write the program again if a mistake is made whie programming the EPROM. In other words, a mistake is not fata, as it is when using PROM. You have the fexibiity to change programs to incude improvements or modifications in the future. SECONDARY STORAGE The ast type of memory we briefy introduce here is caed secondary storage or auxiiary storage. This is memory outside the main body of the computer where we store programs and data for future use. When the computer is ready to use these programs and data, it reads them into primary storage. Secondary (auxiiary) storage media extends the storage capabiities of the computer. We need secondary storage for two reasons. First, because the computer s working memory (primary storage) is finite and imited in size, it cannot aways hod a the data we need. Second, in secondary storage, data and programs do not disappear when power is turned off as they do when semiconductor memories are used. Secondary storage media are nonvoatie memories. This means the information is ost ony if you or the users intentionay erase it. The three types of secondary storage we most commony use are magnetic tape, magnetic disk/diskette, and magnetic drum. PERIPHERAL DEVICES Periphera devices incude a the I/O devices used with a computer system. When these devices are under contro of the CPU, we say they are onine. When they perform their functions independenty, not under direct contro of the CPU, we say they are offine. The periphera devices described in the foowing paragraphs are the ones we commony use: magnetic ink character readers, scanners, bar-code readers, keyto-onine data entry terminas, magnetic tape units, magnetic disk drive units, foppy disk drive units, 1-6

19 cathode-ray tube (CRT) terminas, printers, and potters. Key-to-Onine Data Entry Terminas Magnetic Ink Character Readers Magnetic ink character readers read magneticay inscribed information (ike on a bank check) and transate it to machine code. Scanners Using a key-to-onine data entry termina, a person enters input data into the computer directy from the point of origin. This eiminates the need for human intervention between source recording and the utimate processing by the computer. Magnetic Tape Units Scanners read text, drawings, and photographs and convert them into eectronic representations of the images. Bar-Code Readers Bar-code readers scan data encoded in specia bar codes using refective ight and transate them to machine code. Exampes are the code on the front of this manua and the codes on supermarket and department store products. Magnetic tape units move magnetic tape across read/write heads that read and write the information. Characters are recorded (written) on the tape in the form of magnetized spots aong the entire ength of the tape. On tape, data is stored in a sequentia manner. In sequentia processing, the CPU must begin searching at the beginning of the tape and check each record unti the desired data is found. 1-7

20 Magnetic Disk Drive Units Computer Consoes Magnetic disk drive units are storage devices that read and write information on the magnetized surfaces of rotating disks. The disks are made of thin meta, coated on each side so that data can be recorded in the form of magnetized spots. As the disks spin, characters can be stored on them or retrieved from them in a random (direct) manner. This direct accessing of data has a big advantage over the sequentia accessing of data. You can direct the disk drive to begin reading at any point. Computer consoes usuay incude at east a dispay and a keyboard. They may aso incude a printer. The main consoe is ocated near the CPU and is used by the computer operator to contro the operations of the computer system. Other consoes maybe used at the periphera devices to specify what media to mount, what forms to use in the printer, what aignment is required, and so on. They may aso be used by the periphera equipment operator to start and stop jobs, bring up other periphera devices, requeue jobs, and so on. Computer consoes are not normay used for keying data from source documents for production jobs. Cathode-Ray Tube (CRT) Terminas Foppy Disk Drive Units A cathode-ray tube (CRT) termina ooks ike a teevision with a typewriter-ike keyboard. It aows you, the operator, to enter programs and data directy to the computer. At the same time, it dispays the program or data on the dispay screen of the CRT. It can aso receive information directy from the computer and dispay it on the screen. You can add a printer, a modem, and adapters to the CRT termina to provide for printed output and communications through teephone ines. Printers Foppy disk drive units consist of a diskette drive (the mechanism within which the diskette rotates) and a controer containing the eectronic circuitry that feeds signas into and from the diskette. Diskettes are thin, fexibe patters (foppy disks) coated with magnetic materia so characters can be recorded on the surface in the form of magnetized spots. Just ike hard disks, as the disk spins, characters can be stored on them or retrieved from them in a random (direct) manner. Printers are widey used output devices that express coded characters as hard (paper document) copy. They print computer resuts as numbers, etters, words, 1-8

21 symbos, graphics, or drawings. Printers range from eectric typewriters to high-speed printers. Low-speed ine printers incude the dot-matrix printer commony used with persona computers. High-speed ine printers are normay used with arger computers to print suppy requisitions, paychecks, inventory, or financia reports at 10 ines per second and faster. Laser printers provide high quaity print and print a fu page at one time. They are used with a types of computers. Potters Potters are used with a computer to pot coordinate points in the form of a graph. Digita incrementa potters, in either onine or offine operation with a digita computer, provide a high-speed potting system of high versatiity and reiabiity. For onine operation, a sma adapter unit converts the computer output signas to a form suitabe for driving the potter. INPUT/OUTPUT (I/O) CHANNELS The input/output (I/O) channes provide for communications between the CPU and a periphera devices. This is accompished by eectrica cabes that carry both data and contro information to and from the computer and periphera devices. Signas are transmitted and received through a cabe connecting the CPU and its onine devices. This cabe or ine provides a path for the signa to trave and is caed a channe. Not ony signas for monitoring but aso data are transmitted via channes. A channes between the CPU and the periphera devices are designated as I/O channes. An I/O channe may be used for data input, data output, or data input and output, depending on whether the periphera device handes input ony, output ony, or both input and output. simpex circuits are sedom used, because a return path is generay needed to send acknowedgment, contro information, or some type of error signas. DUPLEX CHANNELS. A dupex channe simpy means that within each cabe connection, there are two paths (ines) for the transmission of data. One path is for sending, and one is for receiving, simiar to your teephone. There are two types of dupex charnes, haf-dupex, and fi-dupex. A haf-dupex channe is capabe of transmitting and receiving signas, but ony in one direction at a time, simiar to citizens band (CB) radio transmissions. Therefore, it is necessary to check that the ine is cear (ide) before starting a transmission. A fu-dupex channe provides for simutaneous transmission in both directions, as in the use of the teephone. Data Transmission Methods Data may be transmitted over a channe in one of two ways, in either seria mode or parae mode. SERIAL MODE. In seria transmission, basicay ony three wires are needed: one to transmit data, one to receive data, and one to ground. The data is sent or received in the form of bits, one after another in seria fashion, as shown in figure 1-7. This type of transmission is highy desirabe whenever the computer system is inked to outside peripheras over a ong distance, such as remote terminas. PARALLEL MODE. Parae transmission is a itte more difficut to hookup than seria. It requires a the data bits in a byte to be transmitted at one time (batch mode); so you usuay have nine or ten wires going between the computer and the periphera devices. You have seven or eight ines for the data bits (figure 1-7) that make up a etter, number, or specia character; one ine to ground; and one or two ines caed handshake ines. The handshaking signas communicate information back and forth between the periphera device and the computer. This information ets the Channe Types I/O channes may be simpex or dupex. SIMPLEX CHANNELS. In simpex operations, communications are in one direction ony, such as a radio. If a device such as a termina were to be connected to such a circuit, it woud ony be capabe of sending or receiving data, but not both. For this reason, Figure 1-7. Seria and parae data transmission. 1-9

22 periphera device know when the computer is ready to accept another character and vice versa. This type of transmission is used when you want to have fast data transfer. Its drawback is that the computer cannot be too far away from the periphera device. MODEMS We said that both signas and data can be transmitted and received through cabes (communications ines), which we refer to as I/O charnes. When we transmit data directy to the computer over ong distances, it becomes necessary to add two other devices, one at each end of the communications ine. These devices are caed modems. The word modem is an acronym for MOduator-DEModuator. A modem converts the digita signa produced by your termina (or the computer) to an audio signa suitabe for transmission over the communications ine. The modem at the other end of the ine reconverts the audio signa back to a digita signa before it is suppied to the computer (or your termina). If this conversion were not carried out, the digita signa woud degenerate and become garbed during transmission. WORKING WITH MICROCOMPUTERS Microcomputers are everywhere. They stand aone. They communicate with minis and mainframes. They communicate with other micros through ocaarea networks. This communication is accompished by the use of software designed to make your computer system function. The operating system software enabes you to insta, seect, and execute a variety of programs. It does this through system/job contro anguages and/or commands. Microcomputer users are not often computer speciaists. They are end users in the functiona areas doing computer processing specific to their requirements. They need to know about the software: the operating system, the communication software, and the appications programs. They need to know about the hardware: the microcomputer, the hard disks and the foppies, the monitor, the keyboard, and the printer. You wi need to hep them configure (set up) the system, insta the operating system and/or appications program, and troubeshoot probems. You need to know more than just merey how to operate them if you are to become a communications speciaist. To be effective, you must keep up with the atest changes in microcomputer technoogy and terminoogy. You must have a good working knowedge of microcomputer hardware components (the computer, peripheras, and accessories). You shoud aso be abe to expain and demonstrate how to use the different types of systems and appications software to both computer and noncomputer personne. Last, but not east, you shoud know how to use the various types of documentation suppied by the manufacturer and software vendors. As a communications speciaist, you must be abe to set up, configure, upgrade, and initiaize microcomputer systems. You wi need to know how to insta appications software so it works with the system s unique configuration. It wi be your job to hep noncomputer users, end users, earn and understand everything they need to know to work in a microcomputer environment. This incudes how to interconnect various periphera devices (keyboard, monitor, printer) to the computer or system unit. It aso incudes how to taior the software for the operating system and the appications software to each user s unique hardware configuration. You need to teach them how to format and abe diskettes; how to propery manage, back up, cean up, and store their fies. You need to demonstrate routine operator maintenance and expain security procedures. When users are having probems with their micros, you may be caed upon to troubeshoot the systems using system diagnostics to hep isoate and determine whether the probem is hardware or software reated. You wi aso be expected to make recommendations and/or arrangements to have repairs made. There wi be times when you wi be expected to make repairs if spare parts are avaiabe. On microcomputers, you wi need to be famiiar with a types of productivity software the program packages (or packaged software). These incude word processing, spreadsheet, and database programs at a minimum. You aso need to earn how to use oca-area network software, communications programs, graphics programs, computer-aided design (CAD) programs, desktop pubishing programs, and so on. You, as a professiona data processor, may aso be invoved with the construction and modification of batch fies. This provides a convenient way to save numerous keystrokes for the user and aow the computer to run unattended for some periods of time. A of these software functions can and have been impemented on both arge and sma scae computers. On arge computer systems, you maybe executing programs through system/job contro anguage commands and processing jobs with muti-ree tape fies or fies that reside on disk packs. You wi be responsibe for ensuring that system contro commands 1-10

23 are correct for a job, seecting a utiity program to copy a fie or create a new fie by specifying the parameters, and working with an onine database management system that keeps up-to-date information on inventory management or personne. In ooking over these ast few paragraphs, possiby you see yoursef as a worker, a supervisor, a teacher, and a troubeshooter, and righty so. Microcomputers make up a significant part of your profession; and because of this, you wi be the person that others wi come to ooking for answers to their questions. The mere fact that you are a communications speciaist gives the outside word, the end users, the impression you know it a; that is, a there is to know about mainframes, minis, and particuary microcomputers. WORKING WITH HARDWARE Microcomputers come in many shapes and sizes with a variety of capabiities. A microcomputer can be designed to operate in a stand-aone configuration or as a component, an inteigent termina, a server for a compex oca-area network (LAN) or arge distributed system. In this chapter, we wi focus our attention on desktop microcomputers that operate in a stand-aone environment. Most stand-aone, desktop microcomputer systems contain at east five hardware components. They are as foows:. The computer or system unit, which normay houses the microcomputer (microprocessor chip[s]) aong with other hardware components and secondary storage devices;. Secondary storage devices (foppy disk drives, hard disk drives, and magnetic tape units), housed either in the system unit or separatey;. A monitor (standard output device);. A keyboard (standard input device); and. A printer (an additiona output device for hard copy). THE MICROCOMPUTER In this section, we wi examine the microcomputer with its individua hardware components. We wi examine it from the inside. You wi see how the components work and how they interface and interconnect with one another. There wi come a time when you maybe required to repace or add a board in a computer to upgrade or expand the capabiities of the system. A few exampes are as foows: You may need to insta an expanded memory board to increase the amount of RAM to accommodate arger appications. You may have to repace the enhanced graphics adapter (EGA) board with an video graphics array (VGA) board to upgrade the graphics capabiities of your system. You may need to insta a communications board. You may receive a new software reease that requires the presence (or absence) of certain boards to function propery. You do not want to find out too ate that your software is incompatibe with your hardware. You might have to answer questions such as the foowing: Wi the graphics software the user wants to order work with the graphics board currenty instaed in the system? Does the user s system have sufficient room to accommodate another hard disk drive? A diagnostics routine may indicate that the disk controer board needs to be repaced, and so on, and so on. For reasons such as these, you wi need to know a ot more about microccomputers (both inside and out) if you are to be effective and abe to hep others in your work environment. The Computer or System Unit The computer or system unit is the main part or heart of the tota microcomputer system. Inside this unit a data is processed, arithmetic and ogic functions are performed, and contro is maintained for the system. If you were to remove the outer cover from this unit (figure 1-8), you woud see a power suppy and as many Figure 1-8. A microcomputer system unit with the cover removed. 1-11

24 as two foppy disk drives and two hard disk drives or any combination thereof, depending upon the particuar configuration of your system. You woud aso see severa boards (aso referred to as cards). Some boards are used to contro the periphera devices of the system, whie other boards work in conjunction with the microprocessor that is ocated on the system or motherboard itsef. These boards provide the fexibiity to add a variety of capabiities to a basic system. Certain boards are required, such as the system board that contains the main microprocessor(s). Others you might add to contro a ight pen or mouse device, or to hande a communications interface. Looking inside the computer system unit (figure 1-8), you wi notice there are 5 avaiabe sots for board insertion. These various boards are pugged into what is caed the motherboard. The motherboard is a printed circuit board that transmits the power and eectronic signas between the other boards and periphera devices. It is mounted to the bottom of the chassis of the computer, as shown in figure 1-9. Memory chips, on the newer micros, caed singe in-ine memory modues (SIMMs), are ocated on the motherboard in a group of 4 or 8 sots. In oder micros the memory chips are ocated on a memory expansion board. Most microcomputers aso have a ithium battery instaed on the motherboard. It provides power to the rea-time cock when the system is turned off. The ife expectancy of this battery is 3 to 5 years. Other boards you are ikey to see in a typica microcomputer are the disk controer board, SCSI adapter board, and video dispay board (figure 1-9). We wi take a ook at each. SLOT A SCSI ADAPTER BOARD. The sma computer systems interface (SCSI) adapter board is used to contro periphera equipment, such as a CD- ROM drive. SLOTS B, D, E, F, AND H. Sots B, D, E, F, and H on this particuar micro are reserved for future use. SLOT C DISK CONTROLLER BOARD. Most disk controer boards are capabe of supporting two interna hard disk drives, two interna foppy drives, and one externa magnetic tape drive for tape backup. SLOT G-VIDEO DISPLAY BOARD. The video dispay board incudes graphics memory chips to provide the system with graphics capabiities. Most micros come from the factory set for VGA (video graphics array) settings. By now, you shoud have a pretty good idea of what you can expect to see inside the system unit in the way of microcomputer boards. Before instaing any interna components within the system unit, you must first carefuy remove the outer cover. Be sure you are authorized to make such changes before removing the cover. However, before you go ooking for a screwdriver, read the owner s manua very carefuy, paying particuar attention to the section on cover remova and the steps to foow. For exampe, the owner s manua might say: Once a cabinet screws have been removed, raise the cover, keeping it as high as Figure 1-9. Boards within the microcomputer system unit and their ocations. 1-12

25 possibe whie puing it forward for remova. This action ensures that none of the interna wires, cabes, or connectors are accidentay pued oose and avoids possibe damage to the components aready instaed inside the system unit. So that you wi have a better understanding and appreciation for this microcomputer, we wi take a coser ook at microprocessor chips and see how they differ from one another. We wi aso examine what a this means to you from a communications speciaist s standpoint. Microprocessor Chips A microcomputer systems are driven by one or more microprocessor chips. A microprocessor chip is made up of thousands of integrated circuits that contain a of the essentia eements of a centra processing unit (figure 1-10). These incude the contro ogic, instruction decoding, and arithmetic-processing circuitry. To be usefu, the microprocessor chip (which is no bigger than your fingernai) must be mounted onto what is caed a carrier package (figure 1-11). This carrier package aong with other chips-memory chips (RAM and ROM) and I/O integrated circuit chips are pugged into specific socket ocations on a circuit board caed the system board or the motherboard (figure 1-12). Figure A microprocessor being mounted onto the carrier package. Of a the boards in the microcomputer, the system board is the most important. But what are the functions of the microprocessor chip? Are a microprocessor chips designed to perform the same functions? Basicay, yes; but there are some significant differences in how they perform their functions. You shoud be aware of these differences, especiay if you wi be working with severa different types of micros. A chip, is a chip, is a chip, OR IS IT? Computer chips, ike everything ese in data processing, have some rather unique and unusua names; names ike Ziog Z-80A, Inte 80C88, MOS Technoogy 6502, Motoroa 68000, and so on. Some chip names contain etters and numbers. Others contain ony numbers. Having the right microprocessor chip in your computer Figure A typica microprocessor computer chip. Figure The system/motherboard showing pacement of the microprocessor, RAM, ROM, and integrated circuit chip. 1-13

26 system makes a the difference in the word in terms of interna processing speeds (33MHz, 66MHz, 120MHz, and so on), number of bits handed (8, 16, or 32 bits), memory size (640K, 4M, 16M, and up), and the appications software it wi run. Each microcomputer contains a specific microprocessor chip as its main processor. A microprocessor chip can typicay hande 8, 16, or 32 bits of information at once. Generay speaking, the more bits a computer can manipuate at one time, the faster it can process program instructions and data, and the arger the main or primary memory it can accommodate. The type of chip in your computer or system unit aso has a great effect on what you can do with your micro. For exampe, operating systems are written to serve a specific microprocessor chip, and appications programs that work under one operating system are not ikey to work under another uness the program is modified. Many appications programs come in severa versions to provide compatibiity with severa operating systems. These are just a few of the reasons why we say it is very important that you read a the documentation that comes with your microcomputer. The Navy uses many different types of microcomputers and microprocessor chips. To give you an idea of the variety, tabe 1-1 ists some of the microprocessor chips. Speciaized Processors Speciaized processor chips have been deveoped to shift some of the workoad from the main Tabe 1-1. Microcomputer Chips and Microcomputers microprocessor chip. For exampe, IBM uses an Inte 8048 chip on the keyboard to determine which keys are being depressed and aso to check to see that the keyboard is communicating propery with the microprocessor. In fact, most periphera devices have one or more speciaized processors embedded in them. Other speciaized processors are the Inte and the faster math coprocessor. These are specia-purpose programmabe microprocessors designed to perform arithmetic cacuations up to 100 times faster than the main microprocessor. A math coprocessor executes arithmetic instructions that woud normay be handed by the main microprocessor s arithmetic-ogic unit (ALU) as we as those the main microprocessor cannot perform because of register constraints. The and are companion chips to the Inte famiy of microprocessors. Computer systems using the 80 series of chips are capabe of very high-speed mathematica operations when the math coprocessor chip is pugged either into or aongside the system or motherboard. Math coprocessor chips are used in SX version computers. The SX denotes that the computer does not have a math coprocessor integrated into the cpu chip. A DX version computer has a math coprocessor integrated into the cpu chip. With the deveopment of the Pentium chip, math coprocessor chips were no onger required to perform arithmetic cacuations. INPUT/OUTPUT DEVICES AND ACCESSORIES To the system unit we must add input/output devices to communicate between us and the computer. These incude the monitor, the keyboard, disk drives, and the printer. We wi ook at each of these devices in the foowing sections, aong with some of the more common accessories found on microcomputers, such as surge protectors, parae to seria converters and vice versa, nu modems, cabes, and switches used for sharing hardware. Monitors (Dispay Devices) Monitors are used as output devices on microcomputers. They are periphera devices that contain a dispay ike a teevision viewing screen. They are the principa ink between you and the microcomputer. Their soe purpose in ife is to aow the microcomputer to communicate its actions to you (the user), so you can act upon those actions to accompish whatever job you are doing. They dispay output from the computer. The monitor is one of the most important peripheras to a micro and is certainy the most visibe. 1-14