CompTIA A+ Exam Notes



  • The four basic components of any computer are input, output, storage and processing
  • ASCII = American Symbolic Code for Information Interchange. 128 char. Extended 255 char.
  • Six fundamental microcomputer components: processor, bus, memeory, disk, video, input/output
  • Old school bus types ISA,EISA,VESA, MCA
  • Another name for a system board is the planar board
  • The nucleus of the PC is the CPU
  • A measurement of speed is MegaHertz
  • Clock speeds are measured in megahertz
  • The larger the cache, the faster the processor
  • the 80286 is equated with the AT and ISA busses
  • The MCA bus was predominatly used by IBM
  • EISA took the most popular features from other busses and expanded on them.
  • the VESA bus is also klnown as the VLbus
  • PCMCIA cards were designed for notebook use
  • Memory is a storage area for fast access.
  • Character strings are groups of alphanumeric data
  • Two factors fro evaluating surge supressors are clamping speed and clamping voltage
  • RAM is volitile memory
  • ROM is non volitile memory
  • Line conditioners may help with unstable power sources.
  • The smallest unit of storage in DOS is a cluster
  • Versions of DOS prior to relase 4.0 support a maximum partition size of 32 MB
  • A double sided 5 1/4″ diskette can be formatted to a maximum of 360 KB
  • The cabling for a floppy drive has a twist in it, on the drive end of the cable.
  • Labeling connections to components is a good idea.
  • To prevent ESD, use a grounding strap.
  • An interrupt allows the computer to suspend what it is doing in order to do something else.
  • The DMA channel for floppy controllers is 2
  • RAID = Redundant Array of Inexpensive Disks
  • Eash device on a PC must have a unique IRQ
  • Older expansion boards may use jumpers or DIP switches that need to be set.
  • A DMA channel allows a peripheral device a direct path to RAM
  • The first thing a POST does is to reset the CPU and program counter to F000
  • Windows near a PC location should have a curtain to reduce the heat effect of sunlight
  • The first step in troubleshooting a PC is to eliminate the possibility of operator error.
  • FDISK is an old school way of fromatting a drive.
  • ICs installed on a circuit board can work lookse over time- this is due to thermal cycling (thermal expansion)
  • Soft memory errors are caused by random events.
  • A hard memeory error is caused by a fialed RAM chip.
  • Voltages may range as high as 15,000 volts in a CRT monitor.
  • The POST test is stored in PROM
  • a keyboard failure is a 301 error code.
  • To conect an ohmmeter to read the value of a circuit, make sure the gate is open.
  • to connect a voltometer to read the value fo a circuit, connect it in parallel.
  • On a standard wall outlet, the smaller of the two slots is considered hot
  • If an outlet is wired backward, it may cause you to get a shock.
  • On older disk drives, constant spinning may cause the magnetic oxide to shift outward.
  • To set up an ESD workstation, place the PC on a grounded mat and connect a wrist strap.
  • CMOS chips are very susceptable to ESD
  • Magentic fields can cause distortion on video displays and loss of data on magnetic storage devices
  • The difference between a spike and a surge- spike=very short, surge =longer
  • power sag- momentary undervoltage condition
  • brownout -prolonged shortage of power
  • transient – overvoltage condition
  • True grounding wrist straps contain a resistor- it is not just a piece of wire.
  • ODI Open DataLink Interface
  • VLM Virtual Loadable Module -used in oldschool novell networks
  • LSL Link support Layer
  • In Token Ring, stations communicate only in one direction
  • Fiber Optic cable is not prone to electromagnetic interference
  • A line printer absorbs the characters sent by the client, but does nothing until it gets a carriage return.
  • Page printers acquire a whole page of data before actually printing.
  • The conversion of characters and drawings to dot patterns is called rasterization.
  • The RIP – Raster Image processor. RIPs use a RISC architecture.
  • Working memory is used by the RIP to store the bit image that will be printed on the page
  • The print spooler is msmory used to store jobs before printing them.
  • DPI Dots Per Inch – the number of dots in one linear inch
  • CPS Characters perSecond
  • PPM Pages Per Minute
  • Engine Speed – a maeasure of the rate that paper rolls through the imaging mechanaism of the printer
  • Fonts built in the printer are called resident fonts.
  • main components of a laser printer – Photosensitive Drum, Cleaning Blade, erasure lamp, primary corona, writing mechanism, toner, transfer corona, fusing roller
  • Toner is moved to the print media by the transfer roller.
  • Toner is transferred from the drum to the print media by a strong negative charge on the corona wire
  • The conditioning wire applies a uniform negative charge to the photosensitive drum.
  • The fuser assembly melts toner particles andpresses them onto the print media.
  • The corona wire transfers the toner to the print media.
  • The printware in a dot matrix printer is fired via an electromagnet, forcing the printwire away from a magnet in the printhead.
  • the six steps of the electrophoto process (EP) – cleaning,conditioning,writing,developing,trasferring, and fusing.
  • A toner cartridge contains a drum, charging roller, developing roller, and scraper blades.
  • Finish refers to the smoothness of the print media.
  • Basis weight – the weight in pounds of 500 sheets of 17×22.5 paper
  • Paper path- the route paper takes through the printer.
  • Friction Feed- Printers grab paper between rubber rollers and use the force of the friction to keep it from slipping.
  • Cut Sheet feeders feed individual cut sheets through the printer. Also known as bin feed systems.
  • Debouncing- cleaning up electrical signals created by the keyboard.
  • LDL Locacal Digital Loopback. Tests the transmitter and reciever of a remote modem and the phone line.
  • The hinge on a notebook is rated on the number of times it opens and closes.
  • Plasics in notebooks are build using EMI sheidling.