chapter 4 - processor fundamentls

Question 1

control unit (CU)

Answer 1

controls data flow through the processor and computer system, and synchronises the F-D-E cycles with control signals

Question 2

arithmetic logic unit (ALU)

Answer 2

responsible for arithmetic, logic or shift processing that may be needed when a program is running

Question 3

clock speed

Answer 3

number of cycles CPU can execute per second

Question 4

bus width

Answer 4

number of wires/lines per bus

Question 5

registers

Answer 5

storage components which have very short access time because of their proximity to the ALU

Question 6

special-purpose registers

Answer 6

registers with a dedicated function

Question 7

general-purpose registers

Answer 7

registers used to temporarily store results to access and re-use in subsequent calculations. if there is only one, it is called the accumulator.

Question 8

current instruction register (CIR)

Answer 8

stores the current instruction while it is decoded and executed

Question 9

index register (IX)

Answer 9

used to modify operand addresses for index addressing when an immediate constant is added to register contents to form operand addresses

Question 10

memory address register (MAR)

Answer 10

stores data read from or about to be written to memory. acts as a buffer to the processor

Question 11

program counter (PC)

Answer 11

stores address of next instruction to be read from

Question 12

status register (SR)

Answer 12

interpreted as individual bits/flags which are set depending on an event or condition

Question 13

immediate access store (IAS)

Answer 13

used by CPU to store data awaiting processing so it is instantly accessible. held temporarily and used for frequently accessed data

Question 14

bus

Answer 14

a parallel transmission component where each wire carries a single bit

Question 15

address bus

Answer 15

carries an address to the memory controller to identify a location in memory which is to be read/written to. unidirectional

Question 16

data bus

Answer 16

carries data in use by processor. bidirectional

Question 17

control bus

Answer 17

used to minimise communication lines by transmitting signals from the control unit. used to synchronise the F-D-E cycle. can be both bidirectional and unidirectional

Question 18

clock

Answer 18

generates timing signals to synchronise events in the processor and the F-D-E cycle. sends a number of regular pulses in a given time interval

Question 19

universal serial bus (USB)

Answer 19

industry standard, which allows automatic device configuration and driver installation

Question 20

video graphics array (VGA)

Answer 20

a video display controller that relays data from a computer to an output device e.g. monitors, projectors, TVs

Question 21

high definition multimedia interface (HDMI)

Answer 21

a proprietary audio/video interface for transmitting uncompressed video data or uncompressed/compressed digital audio data from a HDMI source device, such as a display controller, monitor, video projector, digital TV or audio device

Question 22

interrupt

Answer 22

a signal from a device or program that requires processor attention. may have different priorities

Question 23

immediate addressing

Answer 23

the value used for addressing is in the instruction

Question 24

direct addressing

Answer 24

an address which holds the value is used in the instruction

Question 25

indirect addressing

Answer 25

an address which holds the address which holds the value is used in the instruction. the operand is an intermediate location

Question 26

indexed addressing

Answer 26

the data to the ACC is offset by a base address. the value in the index register is added onto the address in the instruction

Question 27

relative addressing

Answer 27

the operand is the offset from the current address where the value is stored

Question 28

instruction set

Answer 28

a set of statements understood by the processor. groups include data movement, arithmetic operations, jump instructions, compare instructions and modes of addressing

Question 29

linker

Answer 29

a computer program responsible for including links from other files and placing them in a single executable file, library file or object file

Question 30

loaders

Answer 30

responsible for loading programs and libraries into memory for use and preparing for execution

Question 31

directives

Answer 31

information the assembler needs to translate the source code and how it actually constructs the source code. performs tasks such as storage reservation and control functions `

Question 32

macros

Answer 32

sets of instructions that are repeatedly used in a program. they’re written independently and embedded when required, and called using an identifier name

Question 33

comments

Answer 33

not interpreted by the program, but help with understanding

Question 34

system calls

Answer 34

a message sent to the kernel of the OS to allow interaction e.g. access hardware or new processes

Question 35

bitwise operations

Answer 35

fast and simple operations performed by the CPU that treat each bit individually

Question 36

mask

Answer 36

a number used alongside AND, OR and XOR to identify, remove or set a single bit/group of bits in an address/register