CS21 Chapter 2

parity flag

Indicates whether or not an even number of 1 bits occurs in the least significant byte of the destination operand, immediately after an arithmetic or boolean instruction has executed

Instruction Execution Cycle

1.) Instruction Fetch - The CU fetches next instruction 2.) Instruction Decode - CU decodes the instruction 3.) Operand Fetch 4.) Instruction Execution - ALU does execution 5.) Store operand in memory

PCI express

32 bit, Most popular, new used for video

system management mode (SMM)

A CPU power-saving mode that allows a CPU to reduce its speed without losing its place so it does not stop working altogether. SMM also allows the CPU to trigger power saving in other components.

task manager

A Windows utility that shows programs currently running and permits you to exit nonresponsive programs when you click End Task.

motherboard

A circuit board that contains all of the computer system's main components.

instruction pointer

A component of the CPU that keeps track of sequential program execution.

chipset

A group of chips on the motherboard that controls the timing and flow of data and instructions to and from the CPU.

central processor unit (CPU)

A microprocessor which carries out the instructions in computer programs by performing arithmetic and logic operations, and controls inputs and outputs.

SIMD (single instruction, multiple data)

A process that allows the CPU to execute a single instruction simultaneously on multiple pieces of data, rather than by repetitive looping.

application programming interface (API)

A set of software routines that allows one software system to work with another.

data cache

An area of memory in a microprocessor that temporarily holds incoming data.

protected mode

An operational mode of CPUs that allows system software to use features such as virtual memory, paging and safe multi-tasking designed to increase an operating system's control over application software.

flags

Special codes implemented by designers to trigger a required response, alert end users to specified conditions, or encode values. Flags may be used to prevent nulls by bringing attention to the absence of a value in a table.

EFLAGS

Status and control flags, each flag is a single binary bit

code cache

Storage for instructions for deciphering data

wait states

The CPU can incur one or more ________ when it accesses slower storage devices.

dynamic RAM

The most common type of system memory, it requires refreshing every few milliseconds.

arithmetic logic unit (ALU)

The part of the central processing unit that performs arithmetic computations and logical operations.

bus

The paths, or lines, on the motherboard on which data, instructions, and electrical power move from component to component.

clock cycle

The time for one clock period, usually of the processor clock, which runs at a constant rate.

level-2 cache

Memory in the processor package, but not on the processor die.

MMX

Microcode instructions that x86 CPU use to improve performance of multimedia applications and communications.

static RAM

RAM chips that retain information without the need for refreshing, as long as the computer's power is on. They are more expensive than traditional DRAM.

device drivers

Small programs that allow input/output devices to communicate with the computer.

registers

Small, high-speed storage locations that temporarily hold data and instructions.

Virtual-8086 Mode

can directly execute real-address mode software such as MS-DOS programs in a safe environment; if program crashes won't affect other programs running at the same time

carry flag

unsigned arithmetic out of range

segment registers

used to access larger memory space up to one megabyte

data bus

used to transfer actual data

cache

high-speed memory to store most recently used instructions

real-address mode

implements the programming environment of an early intel processor with few extra features; ability to switch into other modes

overflow flag

indicates signed integer overflow

sign flag

indicates that an operation produced a negative result

zero flag

indicates that an operation produced zero

status flag

reflects the outcome of arithmetic and logical operations by the CPU

auxiliary carry flag

set when a 1 bit carries out of position 3 in the least significant byte of the destination operand.

clock

synchronizes the internal operations of the CPU with other system components

operating system

the software that supports a computer's basic functions, such as scheduling tasks, executing applications, and controlling peripherals.

memory storage unit

where instructions and data are held while a computer program is running

direction flag

determines the direction of data moving in memory

level-1 cache

Built into the CPU and gives fast access to the most frequently used data. This level cache is the first one accessed by the CPU and built directly into the CPU core

control unit

Component of a processor that directs and coordinates most of the operations in the computer.

random access memory (RAM)

Computer location where instructions and data are stored on a temporary basis. This memory is volatile.

control flags

Control the CPU's operation

machine cycle

Fetching, decoding, executing, storing

BIOS (basic input-output system)

Firmware that can control much of a computer's input/output functions, such as communication with the keyboard and the monitor.

address bus

Pathway from memory to processing unit that carries the address in memory to and from which data is transferred.

read-only memory (ROM)

Permanent storage; instructions are burned onto chips by the manufacturer.

PCI (peripheral component interconnect)

a bus common to desktop computers that uses a 32-bit wide or a 64-bit data path. Several variations of PCI exist. One or more notches on a PCI slot keep the wrong PCI cards from being inserted in the PCI slot.

floating-point unit

a processor that works with floating point numbers