is a single circuit that either contains a current or does not
used as a means of representing the off/on state of a computer switch, or bit.
a series of circuits whose patterns of off/on current is converted into strings of binary digits called binary numbers
is a group of eight bits and is the method of representing one character of data, such as the essential numbers (0-9)
1 quintillion bytes
1 sextillion bytes
1 septillion bytes
hexadecimal numbers (hex for short)
A number system, referred to as base-16, that uses the numbers 0-9 and the letters A through F to represent a binary string in a shorter, more compact form
floating point standard
A notation standard, created by the Institute of Electrical and Electronics Engineers (IEEE) and used to represent numbers with fractional parts. There is no fixed number of digits before or after the decimal point, so the computer can work with very large and very small numbers PHEWWW
ASCII (The American Standard Code for Information Interchange)
most widely used character code, which is used in minicomputers, personal computers, and computers that make information available over the internet. ASCII uses seven bits and thus represents 128 (2^7=128)
uses eight bits and allows 128 additional characters, like the fractions 1/2l and 1/4; and logical symbols such as ><, for a total of 256 (2^8= 256)
is a boxlike case that comes in a variety of shapes and sizes, and houses the computer's main hardware components.
amount of physical space used by a device
a system unit case designed to sit on the floor next to a desk
A smaller version of the tower that has less internal room for components is called a minitower case
is a specification for how internal components, such as the motherboard, are mounted inside the system unit
is a bracelet that has a cord attached to a grounded object.
keeps the system unit cool
one of the components inside a computer's system unit, typical useful for emitting beeps and other low-fidelity sounds
accommodates the computer's disk drives, such as the hard disk drive, CD or DVD drive, and portable drives
receptacles that accept additional circuit boards or expansion cards
Eight-bit code that IBM mainframe computers and some midrange systems use; ordered using a low-to-high sequence starting with punctuation, lowercase letters, uppercase letters, and then numbers.
uses 16-bit and can represent over 65,000 characters, and can symbolize all the world's written languages; the first 128 codes in the Unicode system represent the same characters in the ASCII system
central processing unit (CPU) microprocessor or processor
for short an integrated circuit chip is that is capable of processing electronic signals.
These processors are designed and programmed to perform only the tasks intended to be done by that device
a heat dissipating component that drains heat from the chip
a processor's list of instructions
A program that is compatible with a given processor and therefore capable of running on that processor
processing or machine cycle
A four-step process performed in the central processing unit (CPU) that involves the fetch, decode, execute, and store operations
under the direction of an embedded program, switches from one stage to the next and performs the action of that stage.
arithmetic logic unit (ALU)
The portion of the central processing unit that performs arithmetic operations, which return numeric values, and logical operations, which return a value of true or false.
One of two groups of operations performed by the arithmetic unit (ALU). The arithmetic operations are addition, subtraction, multiplication, and division. An arithmetic operation returns to the value of the operation
One of two groups of operations performs by the arithmetic logic unit (ALU). An example of logical operation is the comparison of data items to determine whether the first number is greater than the second Logical operations return a value of true or false
are temporary storage areas located within the microprocessor.
fetch and decode
execute and store
the maximum number of bits the CPU can process at once
is an electronic circuit that generates rapid pulses to synchronizes the computer's internal activities, including the movement from one stage of the machine cycle to another
billions of cycles per second
The speed of the internal clock of a microprocessor that synchronizes and sets the pace of the computer's internal activities, including the movement from one stage of the machine cycle to another.
refers to the design of any CPU that can execute more than one instruction per clock cycle
a technique that feeds a new instruction into the CPU at every step of the processing cycle so that four or more instructions are worked on simultanesouly
if the CPU needs the results of a completed instruction to process the next one
is a set of parallel wires that acts as an electronic highway on which data travels between computer components
the width of a CPU's data bus
the processor executes and temporarily stores the next instruction in case it proves useful
the processor tries to predict what will happen (with surprisingly high degree of accuracy).
a technique that uses more than one processor to execute a program
a process by which the CPU gives the user the illusion of performing instructions from multiple programs at once when in reality the CPU is rapidly switching between the programs and instructions
which is a collection of chips that work together to provide the switching circuitry needed by the microprocessor to move data throughout the computer
input/output (I/O) bus
refers specifically to the pathway that extends beyond the microprocessor to communicate with input and output devices.
PCI (peripheral component interconnect) bus
a slower bus that connects devices like hard drives and sound cards to the faster microprocessor system bus
refers to the chips, located on the motherboard or within the CPU, that retain instructions and data to be accessed by the CPU
volatile memory, which means it is not permanent and its contents are erased when the computer's power is switched off
-Receive and hold program instructions and data while being used by the system
-Provide those instructions and data to the CPU when needed
-Hold the results of the CPU's processing until an instruction is received to transfer it to a printer or permanent storage device
memory address/ direct access storage (IBM)
(in binary form) enables the location to be found and the content within to be accessed directly
memory modules or memory cards
a small circuit board that holds several RAM chips and fits into special slots on the motherboard
dual inline memory modules (DIMM)
what most RAM are today; have 168-pin connector and a 64-bit data transfer rate
single inline memory module (SIMM)
used a 72-pin connector and a 32-bit data transfer rate
the amount of RAM the program uses while it operates
a term used to refer to a portion of the hard drive that the operating system treats as a portion of RAM when RAM is full
is a small unit of ultrafast memory built into or near the processor that stores frequently or recently accessed program instructions and data
is a unit of 4KB to 16KB of ultrafast memory included in the microprocessor chip that runs at approximately 10 nanoseconds. Primary cache is the fastest memory
is a unit of up to 512KB of ultrafast memory that can be located within the microprocessor, but further from registers than lvl. 1 cache, or on a separate cache chip located on the motherboard
one-billionth of a second
Level 3 cache
is found on systems with newer microprocessors, like Intel's Xenon processor, that are located in some servers and workstations.
a type of nonvolatile memory in which instructions are prerecorded and not erased when the system shut down
BIOS (basic i/o system)
the first code run when a system is powered on. It checks and initializes such devices as the keyboard, display screens and disk drives
controls a variety of actions including starting the power-son self test and verifying that other components of the system are functioning correctly
a program that locates and loads the operating system into RAM
POST (power-on self test)
a program that is run when the system is started. It checks the circuitry and RAM, marking any locations that are defective so that they do not get used
PROM (Programmable read-only memory)
can be written on only once, but requires a special writing device. It is used to hold startup programs that are bug free and are never meant to be changed.
electrically programmable read-only memory is erasable PROM that can be reused many times.
electrical erasable programmable read-only memory that can be rewritten many times while the chip is on the computer
similar to EEPROM except that flash EPROMs are erased in blocks, whereas regular EEPROMs are erase one byte at a time.
drive activity light
indicates your hard drive is accessing data
which indicates whether the power is on
is a physical receptacle located on the system unit or on an expansion card that is visible on the outside of the unit
small screws that are usually attached to the plug and and are used to connect the plug to the system unit or the expansion card extender to prevent an accidental disconnect
USB ports (universal serial bus)
can connect a variety of devices, including keyboards, mice, printers, and digital cameras, and were designed to replace older parallel and serial ports
is the ability to connect and disconnect devices without shutting down your computer
refers to a set of standards, jointly developed by the Intel Corporation and Microsoft, which enable a computer to automatically detect the brand, model, and characteristics of a device when you plug it in and configure the system accordingly
a device that plugs into an existing USB port and contains four or more additional ports
an interface Apple created and standardized as the IEEE 1394 High Performance Serial Bus specification
the name of FireWire on non-Apple systems
video graphics array (VGA) connector
a 15-pin male connector that works with standard monitor cables
digital visual interface (DVI) port
lets LCD monitors use digital signals
video circuitry that is built into the motherboard on some computers
is a credit card-sized adapter that fits into a designated slot to provide expanded capabilities such as wireless communication, additional memory, multimedia, or security features
is an older technology, device, or application that is being phased out in favor of new advances in technology
were one of the earliest types of ports and were often used dial-up modems to achieve two-way communication
were commonly used to connect a PC to a printer but have been replaced by USB ports and Ethernet ports
were typically used for mice and keyboards, but were not interchangeable.
SCSIs (pronounced scuzzy)
small computer interface ports were a type of parallel interface that enabled users to connect up to 15 SCSI-compatible devices, such as printers, scanners, and digital cameras, in a daisy-chain series