Computer Systems Support
Comp TIA A+ Guide to Hardware
Managing, Maintaining, and Troubleshooting, 4th Edition
Intro Pages
q Flowchart describing CompTIA A+ Essentials
q Breakdown of domains covered in four possible exams a student can take
Ch. 1
q Several technical diagrams given with parts of the computer labeled
q Student must be able to classify parts based on certain characteristics (examples: hardware used for input versus hardware used for output, distinguishing between data cables and power cables often based on their shape)
q Understanding and application of the term “parallel”
q Units such as megahertz or gigahertz
q 800 MHz means data or instructions can be put on they system at the rate of 800 million every second
q Power supply receives 110-120 volts of AC power from a wall outlet and converts it to a much lower DC voltage (students must have some basic understanding of electricity to even understand this sentence and what is actually happening here)
q Constant need to categorize parts of the whole into smaller groups and subgroups based on their function within the computer/classification (a concept used REPEATEDLY in mathematics)
q Know how many bits are in a byte
q Learning to think in binary and hex requires understanding of exponents
Ch. 2
q Understanding how to use the various tools associated with PC technician support repairs (multimeter, AC outlet group tester, network cable tester, coop-back plugs to test ports, etc.)
q Various tables throughout the chapter that discuss proper care and maintenance of hardware
q Following a specific order of operations when disassembling a computer is crucial so as not to damage any parts; the same is true of reassembling the computer
q The POST is a series of tests performed by the startup BIOS to determine if it can communicate correctly with essential hardware components required for a successful boot (many times mathematically when a series of tests must be performed to make a determination)
q Processor begins working and initializes itself when system is turned on (idea of initial value, or initial conditions, initial velocity in some algebraic formulas, etc.)
q Understanding of if/then language to know how the system runs various start-up tests; same logic used in proofs
q Diagnostic skills and questioning techniques used in troubleshooting a problem on a computer
q Divide and conquer method of solving a problem (Continue to isolate the problem to a smaller and smaller level until you have zeroed in on it)
q Inductive reasoning used in trading known bad parts for good and known good parts for bad
q Flowchart on pg. 79 shows troubleshooting when facing a computer problem
Ch. 3
q +/- Numbers used to discuss the amount of volts power supplies for the AT systems supply to the motherboard and other components
q Understanding of the dimensions given for Baby AT motherboards, ATX motherboards, and various other motherboards
q Figure 3-7; Power supply connectors defined by the ATX specifications (another use of +/- voltage
q Table 3-2; Measures of Electricity—shows various units used to measure electricity, what they mean and a computer example where the technician would have to be familiar with the unit
q Understanding the difference between AC and DC current; AC oscillates 60 X’s/second (60 hertz); voltage constantly alternating from + to –
q Charge is either positive or negative; manipulating the charge to the transistor allows it to hold a logic state of either on or off; represents binary 1 or 0 (much like additive or multiplicative inverses)
q One joule is the work or energy required to produce one watt of power in one second
q Understanding the rating of suppressors based on clamping voltage
q To determine the VA required to support your system, multiply the amperage of each component by 120V and then add up the VA for all components
q How to determine if you have an inadequate power supply to your computer—estimate how much total wattage your system needs by calculating the watts required for each device and adding them together; see if you have a power supply that supports this estimated total
q The temperature inside the case should never exceed 100 degrees F
q Several of the projects at the end of Ch. 3 require student to make calculations such as comparing prices and ratings of two different surge suppressors or total wattage requirements of all drives in a computer system; students are then asked to process that information to make meaningful conclusions about it
Ch. 4
q Various numerical values to describe processors (examples: today’s front-side buses run at 1066, 800, 533, or 400 MHz; processor core frequency measured in gigahertz, such as 3.2 GHz; word size, either 32 bits or 64 bits, which is the number of bits a processor can process at one time; etc.)
q Bus frequency is the frequency or speed at which data is placed on a bus
q System bus frequency X multiplier = processor frequency
q Overclocking—setting processor frequency at 5%, 10%, 15%, 20%, or even 30% higher than the default frequency
q Figure 4-2 shows various processors, their processor speed ranges, their system bus, and gives a description
q Pin grid array (pins aligned in uniform rows around the socket); staggered pin grid array (pins staggered over the socket to squeeze more pins into a small space); land grid array (uses lands instead of pins); sockets are all square or nearly square
Ch. 5
q Approaches to selecting motherboards: select the board that provides the most room for expansion, select the board that best suits the needs of the computer’s current configuration, select a motherboard that meets your present needs with moderate room for expansion (all approaches require some calculation and/or data analysis as well as estimation skills)
q Understanding of synchronized versus asynchronously working components of a computer
q Bus evolution section gives numerical values such as how many bits in the data path, number of volts in the power supplied expansion card, and how many MHz for buses as they have evolved over time
q Extensive table for CMOS settings (table 5-5) which contains the category, setting, and description so technician can see CMOS settings and their purpose
Ch. 6
q SIMMs are rated by speed, measured in nanoseconds; the smaller the speed rating, the faster the chip (inversely proportional)
q CAS or RAS Latency (“Column Access Strobe” or “Row Access Strobe”) is the number of clock cycles it takes to write or read a column or row of data off a memory module; concepts of rows and columns used many times in mathematics, esp. w/matrices
q Calculations involved with determining how much memory your computer already has as well as your memory expansion needs and if your computer will support them with its current setup
q If you multiply the density times the number of components on a RIMM, you get the total amount of memory on one RIMM (see table 6-2 for examples of using this calculation)
q Reading ads about memory modules—density is written as two numbers separated by an X, such as 16 X 64, and is read “16 by 64”; the second number is 64 if it’s the width of the data bus in bits, grouped as eight bits to a byte; if the second number is 72, then it’s the width of the data bus plus an extra bit for each byte, used for error checking and correction…
q Projects at the end of Ch. 6 require doing some calculations in order to estimate the cost of upgrading memory
Ch. 7
q Before data can be written to a disk, it must first be mapped in concentric circles called tracks, which are divided into segments called sectors
q Surface of disk spins at 360 rpms (revolutions per minute)
q 3.5 inch, HD floppy disk has 80 tracks X 18 sectors per track on each side, for a total of 1440 sectors on each side; one sector per cluster, making 1440 X 2 sides, or 2880 clusters; each cluster holds 512 bytes (one sector) of data; comes out to 1,474,560 bytes of data (can be converted to kilobytes and finally to 1.44 MB)
q The tracks on a read-write head that are equidistant from the center of the platters make one cylinder
q Calculating the drive capacity on older drives and on today’s drives
q Mathematics behind understanding the 137 GB barrier involved understanding of exponents, binary, and unit conversion at minimum
q LUN (logical unit number) used to identify trays in a CD-ROM changer, for example; Figure 7-29 shows Wide SCSI ID binary jumper settings for internal devices; must have some understanding of how many possible configurations there are given four columns with each column being able to be “on” or “off”
q Technician must be mindful of factors that affect the decision of how to select a hard drive, many of them numerical values and ranges
q Installations using Legacy BIOS also requires technician to make and be mindful of various calculations
Ch. 8
q One roller in mouse tracks the x-axis (horizontal) movement of the mouse, and a second roller tracks the y-axis (vertical movement); reports movement to CPU to make mouse move in direction user moves it (relates to translations in both Algebra and Geometry)
q Vertical deflection plates and horizontal deflection plates present in a CRT monitor
q Two layers of electrodes in an LCD monitor make up the electrode matrix (each intersection of a row and column forms a pixel)
q Refresh rate, or vertical scan rate, is the number of times in one second an electronic beam can fill the screen with lines from top to bottom; response time is the time it takes for an LCD monitor to build all the pixels for one screen or frame and is measured in milliseconds
q Dot pitch is the distance between the spots, or dots, on a CRT screen that the electronic beam hits; each composite location on the screen is really made up of three dots and is called a triad
q Resolution is a measure of how many spots on a CRT screen are addressable by software; each addressable location is called a pixel
q For LCD monitors, the number of pixels on the screen is sometimes called the resolution and sometimes called the pixel pitch
q Understanding and applying the following terms: active and passive matrix, contrast ratio, and native resolution
q AGP standards summarized in table 8-4 includes the standard, speeds, maximum throughput, voltage, and slots supported
Ch. 9
q Sampling rate of a sound card, which is the number of samples taken of the analog signal over a period time, is usually expressed as samples (cycles) per second, or hertz (Hz)
q Our ears detect up to about 22,000 samples per second, or Hz; sampling rate of music CDs is 44,100 Hz or 44.1 kHz (twice the frequency of the analog signal)
q Understanding the difference between an 8 bit sampling size (allows for a range of –128 to 127) versus a 16 bit sampling size (allows for a range of –32,768 versus 32,767)
q MP3 Players—can reduce the size of a sound file as much as 1:24 without much loss of quality; MPEG compression can yield a compression ratio of 100:1 for full-motion video (30 frames per second or fps)
q Concept of constant linear velocity (CLV)—needed to create the effect of constant speed as a CD turns; makes sure beam is over a sector on the CD for a set amount of time, no matter where the sector lies on the CD; technician must understand that it would normally read faster if it is reading a sector toward the center
q Constant angular velocity (disc rotates at a constant speed)
q Half-life (sometimes called life expectancy or shelf life) of the disk is the time it takes for the magnetic strength of the medium to weaken by half
Ch. 10
q Understanding the mathematics behind IP Addresses (32 bits long, made up of 4 bytes separated by periods)
Ch. 11
q Voltage range on the DC connector of a notebook should be plus or minus five % of the accepted voltage
Ch. 12
q Figure 12-2 is a “cross-section” of the drum, mechanisms, and paper in a printer
q Charge of –600 V is put on the surface of the drum
q 1200 dots per inch (dpi) down a linear pass, combined with 1200 passes per inch of drum circumference, accomplish the resolution of 1200 X 1200 dpi in many desktop laser printers
q Understanding the voltage differential that must occur for laser printers to operate
q Flowchart figure 12-49 helps technician isolate a printer problem
Math Repeatedly Used:
q In all texts related to this course, students must understand a series of steps to solve an issue and follow that logical series of steps (algorithm); this is done REPEATEDLY in mathematics (examples might include the algorithm for solving a linear equation, for graphing a parabola, or for writing a proof)
q Diagnostic work a technician must do often requires them to associate a set of symptoms or characteristics with a particular problem, thus being able to make an educated guess about what the problem might be based on the customer’s description of the problem; a student in Algebra or Geometry would go through a similar thought process when asked to do several different types of problems (examples: knowing a graph should be linear and then figuring out why it doesn’t turn out that way when the student plots the points; knowing the characteristics that define a kite and being able to determine if a figure meets the requirements to be a kite based on that information)