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