Processor fundamentals Flashcards
ALU
Requires arithmetic or logic operations to be carried while being run. It is a the arithmetic logical unit of the computer which does all the mathematical functions
CU
Reads the instruction from memory, the instruction is interpreted. Signals are generated along the control bus to tell the computer what to do
System clock
to coordinate / synchronise the actions of other components in the CPU
* to send / receive control signals along the control bus
* to manage the execution of instructions (in sequence)
* to control the communication between the components of the CPU
CIR
Holds the op code and operand of an
instruction ready for it to be decoded
MAR
Holds the address where data is to be
written to or read from
MDR
Holds data read from, or to be written to,
memory
PC
Holds the address of the next instruction to
be read
ACC
Holds the result of the last instruction
executed by the ALU
IX
to store a value that is added to an address to give another address
Status register
to store flags which are set by events // from the results of arithmetic and logic operations and interrupt flags
MU
Holds flags that are set when the Arithmetic
and Logic Unit (ALU) executes instructions
Fetch Execute cycle
[PC]—-> MAR
[MAR] —-> [MDR]
[MDR]—->[CIR]
PC<—- [PC] +1
Address bus
Unidirectional, between CPU and memory of the address bus. Prevents addresses being carried back to the CPU
width is important wider the bus more memory locations it can address at any given time
Data bus
Bidirectional, allows data to be sent in both direction. Carries out data from CPU to memory. Data can be an address or a instruction or numerical value.
Control bus
Bidirectional carries signals from CU to other parts of the computer.
What affects Computer speed
Width of busses
Clock speed
Cache memory
No. of cores
Overclocking
Clock speed can be changed by going into BIOS. Using a higher clock speed leads to problems.
* An instruction will not be complete with the given amount of time, so the computer will frequently crash and become unstable.
* Overheating of the CPU
Cache memory
Improves processor performance. Uses RAM, memory gets lost after no power is supplied. Uses SRAM, there is no need to keep refreshing as it slows down access time
It stores frequently used data and instructions that need to accessed faster.
Cores
A core is made up of a ALU, CU and registers. CPU is made up of two cores - dual cores. quad cores - 4 cores.
Using more cores increases clock speed, BUT they do not always increase a processors speed.
Dual cores increases speed - one channel, needs CPU to communicate with both cores
Quad cores decreases speed - 6 channels too many channels, CPU overworks, reduces speed
USB ports
Universal serial Bus - detects that a device is present due to the change in the voltage level.
Device is recognized and the device driver is loaded, so that it can communicate with the device
HDMI
Supports high definition signals.
Widescreen format
Uses a greater number of pixels when compared to VGA
Screens have a faster refresh rate.
Large range of colors
Pros and cons of HDMI
Pros - standard for modern television
fast data transfer
improved security
modern digital system
Cons - not robust
breaks the connection by just moving the device
limited cable length
Pros and cons VGA
Pros - Simpler technology
only on standard
easy to spilt and signal
connection is secure
Cons - Old out dates analogue tech
easy to bend the pins
cables must be very high grade
Interrupts
Interrupt signal appears
checks priority
Status of the tasks that were running are saved.
Interrupt service routine is executed.
Interrupt is serviced, task continued from its prior point
Indirect addressing
the address to be used is at the given address
Relative addressing
the address to be used is an offset number of locations away, relative to the address of the current instruction
Indexed addressing
form the address from the given address plus the contents of the index register
Opcode
The opcode is the instruction that is executed by the CPU
Operand
Data or memory location used to execute that instruction
