Input Device - An externalobject that provides input for the computer. Some common input devices include:keyboard, mouse, joystick, pen tablet, keyboard, scanner, digital camera, videocamera, and microphone.
Output device - An externalobject that provides output for the computer. Some common output devices include: monitor, projector, TV screen,printer, plotter, speakers.
Bit - A bit is a single digit number (a zero or a one) and is the smallestunit of computer data.
Byte - It takes eight bits to make one byte. It is the quantity of information that is stored.
Modem - A modem is a communications device that can be either internal orexternal to your computer. It allows one computer to connect another computerand transfer data over telephone lines.
CPU (CentralProcessing
Unit) – The main area of thecomputer system
that contains the control unit and arithmetic-logic unit. This part of the computer takes
instructions. Some current Intel PC’s
are Pentium IV, Dell,Gateway, and AMD. These PC’s can work upto 2 – 4 GH³ (Which is
the speed the computer works at) and they use aCISC. Some of the Motorola options areApple and
Macintosh that uses the RISC chip and currently using a G5 that runsat less
than 2 GH³.
Howfast
is reasonable – about 40 gig or higher due to
theincrease of interest in pictures and movies.
CISC(Complex Instruction Set Computer) – This chip is better for the math
actionsused in a CPU.
RISC(Reduced Instruction Set Computer) – This chip is better for the
memoryoriented and data actions used in the CPU.
ALU(Arithmetic Logic Unit) – This part of the CPU deals with the math and
testingthat come with the instructions.
ControlUnit
– This part of the CPU deals with all the instructions that come in andout of
the computer.
ROM(Read Only Memory) – This part of the computer holds instructions that
thecomputer uses daily and never changes. The instructions can only be read but
not edited (an example is thestartup instructions and microcobe)
Cache–
An area in the computer that is used to store information while the CPU
isrunning other instructions and information.
It is also a tool to help the computer work with the different
speedsused in the various parts of the CPU.
RAM (Random Access Memory) - Any memory that can be accessed whether first or last on the list (like scene selection on a DVD movie. A good RAM to own is 512 MB to 1GB.
SDRAM
- (Synchronous DRAM) A type of DRAM memory chip that has been widely used since
the latter part of the 1990s. SDRAM chips eliminate wait states because they
are fast enough to be synchronized with the CPU's clock. The chip is divided
into two cell blocks, and data are interleaved between the two. While a bit in
one block is accessed, a bit in the other is prepared for access. This allows
SDRAM to burst subsequent, contiguous characters at a much faster rate than the
first character.
SGRAM - (Synchronous Graphics RAM) A type of dynamic RAM chip that is similar to the SDRAM
technology, but includes enhanced graphics features for use with display
adapters. Its Block Write and Mask Write functions allow the frame buffer to be
cleared faster and selected pixels to be modified faster.
VRAM - Also called
"VRAM," it is the type of memory used in a display adapter. Video RAM
is designed with dual ports so that it can simultaneously refresh the screen
while text and images are drawn in memory. It is faster than the common DRAM or
SDRAM chips used as main memory in the computer.
BUS - A common
pathway, or channel, between multiple devices. The computer's internal bus is
known as the local bus, or processor bus. It provides a parallel data transfer path
between the CPU and main memory and to the peripheral buses. A 16-bit bus
transfers two bytes at a time over 16 wires; a 32-bit bus uses 32 wires, etc.
The bus is made up of two parts: the address bus and the data bus. Addresses
are sent over the address bus to signal a memory location, and the data are
transferred over the data bus to that location.
BIOS - (Basic Input Output System) An
essential set of routines in a PC, which is stored on a chip and provides an
interface between the operating system and the hardware. The BIOS supports all
peripheral technologies and internal services such as the realtime
clock (time and date). On startup, the
BIOS tests the system and prepares the computer for
operation by querying its own small CMOS memory bank for drive and other
configuration settings. It searches for other BIOS's on the plug-in boards and
sets up pointers (interrupt vectors) in memory to access those routines. It
then loads the operating system and passes control to it. The BIOS accepts
requests from the drivers as well as the application programs. BIOSs must
periodically be updated to keep pace with new peripheral technologies. If the
BIOS is stored on a ROM chip (ROM BIOS), it must be replaced. Newer BIOSs are stored on a flash memory chip that can be
upgraded via software.
SCSI - (Small Computer System Interface) Pronounced
"scuzzy." SCSI is a hardware interface that
allows for the connection of up to 15 peripheral devices to a single PCI board
called a "SCSI host adapter" that plugs into the motherboard. SCSI
uses a bus structure and functions like a mini-LAN connecting 16 devices, but
the host adapter counts as one device. SCSI allows any two devices to
communicate at one time (host to peripheral, peripheral to peripheral).
USB - (Universal Serial Bus) A widely used hardware interface for attaching peripheral
devices. USB ports began to appear on PCs in 1997, and Windows 98 was the first
Windows to support it natively. Within a few years, USB became popular for
connecting nearly every external peripheral device. Replacing the serial and
parallel ports on a PC, at least four USB ports are standard on every computer.
PCI - (Peripheral Component Interconnect)
The most common I/O bus in use today. It provides a
shared data path between the CPU and peripheral controllers in all kinds of
computers from laptops to mainframes. Designed by Intel, Compaq and Digital, it
first appeared in PCs in 1993 and co-existed with the ISA bus for many years.
Today, most PCs have only PCI slots and one AGP slot for a display adapter.
Active Matrix Display
(TFT) - (Thin Film Transistor) The term typically refers to
active matrix screens on laptop computers. Active matrix LCD provides a sharper
screen display and broader viewing angle than does
passive matrix.
Pixel - (PIX [picture] ELement) Generally,
the smallest addressable unit on a display screen or bitmapped image. Screens
are rated by their number of horizontal and vertical pixels; for example,
1024x768 means 1024 pixels are displayed in each row, and there are 768 rows
(lines). Likewise, bitmapped images are sized in pixels: a 350x250 image has
350 pixels across and 250 down. With
color systems, each pixel contains red, green and blue subpixels,
and the subpixel is actually the smallest addressable
unit. The monitor's circuits address subpixels, and
the software may also.
CGA - (Color/Graphics Adapter) The first video display standard for the IBM PC. This low-resolution system was superseded by EGA and then VGA. CGA required a digital RGB Color Display monitor.
EGA - (Enhanced Graphics Adapter) An early IBM video display standard that provided
medium-resolution text and graphics. It required a digital RGB Enhanced Color
Display or equivalent monitor and was superseded by VGA.
VGA - (Video Graphics Array) The display standard for the PC. VGA uses an analog monitor,
and PC display adapters output analog signals. All CRTs and most flat panel
monitors accept VGA signals, although flat panels may also have a DVI interface
for display adapters that output digital signals. Although VGA may refer to the PC's display
system in general, "VGA resolution" typically refers to the original
resolution of 640x480 pixels and 16 colors. This base resolution is not widely
used except for tiny monitors or booting up the computer in Safe Mode.
XGA – (EXtended Graphics Array) A screen resolution of 1,024x768 pixels. The term stems
from IBM's XGA display standard introduced in 1990, which extended VGA to
132-column text and interlaced 1,024x768x256 resolution. XGA-2 later added non-interlaced
1,024x768x64K.
Hard
Drives - The primary
computer storage device, which spins, reads and writes one or more fixed disk
platters. In practice, the terms "hard drive" and "hard
disk" are used synonymously. Hard drives are the storage medium in desktop
and laptop computers as well as all servers and mainframes throughout the
world. They are also used in printers for storing fonts and print jobs as well
as digital music players and a myriad of other portable and stationary
computer-based devices. Although removable disks encased in cartridges use the
same "hard" disk media and a similar drive technology, they are
mostly called "removable drives" rather than hard drives. The term "hard" differentiates
high-capacity rigid disks made of aluminum or glass from low-capacity floppy
disks made of plastic. The amount of
storage on a hard disk, measured in gigabytes. Your capacity requirement is
derived from the size of your applications, but mostly the amount of data you
need to store. Multimedia files such as graphics, animations and video take up
considerably more space than text.
DVD - (Digital VideoDisc or Digital
Versatile Disc) An
optical digital disc for storing movies and data. Introduced in the
CD-ROM - (Compact Disc Read Only Memory) A compact disc format used to
hold text, graphics and hi-fidelity stereo sound. It uses a different format
for recording data than the audio CD (CD-DA), from which it evolved. An audio
CD player cannot play CD-ROMs, but CD-ROM players can play audio discs. In a
PC, most internal CD-ROM drives (players, readers) connect to the EIDE (ATA)
interface on the motherboard. External drives connect via USB or SCSI. CD-ROMs hold 650MB of data (681,984,000
bytes), which is equivalent to about 250,000 pages of text or 20,000
medium-resolution images. Some CD-ROM discs claim 680MB capacity by dividing
the 681 million by one million instead of the binary number 1,048,576.
CDRW-ROM - (CD-ReWritable) The only rewritable CD technology. CD-RW
disks look like other CD media, but with close inspection, they have a more
polished surface with a very dark blue-gray cast. Similar to a hard disk, files
can be added and deleted, and the media must be formatted before use. However,
unlike a hard disk platter, which can be rewritten millions of times, CD-RWs have a maximum limit of 1,000 rewrites. The CD-RW is the most versatile CD drive, and
most new CD drives are actually CD-RWs. Not only can
a CD-RW drive read all CD formats and write CD-RWs,
it can be used to burn "write once" CD-R media. CD-RW uses phase
change technology to alter the reflectivity of the disk surface, but this
reflectivity is lower than other CD formats, and older CD-ROM drives that lack MultiRead capability cannot read them.
Zip Drive - A
3.5" removable disk drive from Iomega. Zip disks come in 100MB, 250MB and
750MB varieties, with the latter introduced in 2002 using USB and FireWire
interfaces. The 250MB drives, introduced in 1998, also read and write 100MB
disks. The 750MB drives read all, but only write 250MB and 750MB disks. Zip disks are a floppy-like technology that
uses design concepts from hard disks and Iomega's earlier Bernoulli disks. The drive
is bundled with software that can catalog the disks and lock the files for
security. When Zip disks were introduced in 1995, they became popular very
quickly.
Super
Drive - An optical drive for the Macintosh from Apple that writes DVDs and CDs. It supports write-once DVD-R and CD-R as well
as rewritable CD-RW media. The name used to refer to the Mac's floppy drive
that stores 1.44MB and also reads and writes earlier Mac 400 and 800KB disks,
as well as Apple II ProDOS, DOS and OS/2
formats. An earlier floppy disk drive
from Imation Corporation,
WORM
Memory - (WORM) (Write Once Read Many) An
optical disk that can be recorded only once. Updating requires destroying the existing data
(all 0s made 1s), and writing new data to an unused part of the disk. There are two kinds of WORM technologies.
Ablative large-format (12-14") WORM is the traditional type, which makes a
permanent change in the optical material. Continuous composite write (CCW) WORM
is a mode in multifunction 5.25" optical (MO) drives that emulates a WORM
drive. The data are not permanently changed, but the drive contains firmware
that ensures that recorded areas are not rewritten.
Tape Drive - A
physical unit that holds, reads and writes the
magnetic tape.
Floppy
Drive - A reusable magnetic storage medium introduced by IBM in 1971. It was called a floppy because the first
varieties were housed in bendable jackets. Woefully undersized for today's use,
it is no longer standard equipment on computers. However, until the early
1990s, the floppy was the primary method for distributing software and was
widely used for backup. By the mid-1990s, it had mostly given way to the
CD-ROM. Also called a
"diskette," the floppy is a flexible circle of magnetic material
similar to magnetic tape, except that both sides are used. The drive grabs the
floppy's center and spins it inside its housing. The read/write head contacts
the surface through an opening in the plastic shell or envelope. Floppies spin
at 300 RPM, which is from 10 to 30 times slower than a hard disk. They are also
at rest until a data transfer is requested. Following are the three types
developed, from newest to oldest, and their raw, uncompressed storage capacity.
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