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.