Internal computer architrcture Flashcards
what is the CPU
CENTRAL PROCESSING UNIT
What is the RAM
Random access memory
what is the ALU and what does it do
- the arithmetic logic unit does arithmetic and logic operations
what is the CU and what is its role
THE CONTROL UNIT:
- control operation of fetch-execute cycle
- Determines the type of an instruction
- To execute (some) instructions;
- To synchronise operation of processor;
- To send control signals to other components;
- To control the transfer of data between registers;
- To handle interrupts
examples of registers within the CPU
- IR
- CIR
- ACC
- MDR
- PC
what are registers
memory locations within the processor which work at very high speeds, and they are used to control the fetch decode execute cycle
summarise the PC
- program counter
- stores the address of the next instruction
summarise the MAR
- memory address register
- stores the address of the data or the instructions that are to be fetched from or sent to the memory
summarise the MDR
- memory data register
- temporarily stores the data that is to be sent to or fetched from the memory
summarise the CIR
- current instruction register
- stores the actual instruction being decoded and executed
what does the ACC do
the accumulator stores the result of calculations
summarise address bus
carries the address of the instruction or data in the MAR from the processor to the memory, unidirectional
summarise data bus
the data bus carries data between the processor and the memory, bidirectional
summarise the control bus
controls signals between the processor and the components, bidirectional
What does the status register do
- Contains information about the state of the processor
What does the clock do?
- It is the electronic unit that synchronises related components by generating regular pulses
- Measured in hertz
- The higher the clock rate, the faster, the computer may work
Summarise, general-purpose registers
- temporarily holds data and instructions that are being processed by the cpu
What is the program counter responsible for?
It holds the address of the next instruction to be executed
What is the memory buffer register responsible for?
It’s used to temporarily stored the data which is read from a written to memory
how does clock speed affect processor performance
- the CPU is regulated with clock signals
- the faster these cycles are, the more instructions can be executed per second
how does cache size affect processor performance
- A larger cache stores more frequently used data closer to the CPU, reducing data retrieval time.
- improves CPU efficiency by reducing the need to fetch data from slower main(RAM) memory
what is cache
small amount of expensive , fast memory inside/near to the CPU
what are the levels of cache
L1 - embedded in the CPU chip, is the smallest and fastest
L2 - fairly fast and medium size (256kb - 2mb)
what is a core
a complete copy of a CPU
how does the number of cores affect the performance of the processor
- multiple cores allow a CPU to perform parallel processing, where different tasks can be accessed simultaneously
what is the purpose of the CPU
to fetch, decode and execute instructions
what does fetch do
causes the next instruction to be fetched from main memory
what is a bus
a set of parallel wires connecting two or more components of a computer
purpose of the control bus
to transmit command, timing and specific status information between system components
what is a word
a fixed size group of digits which is handled as a unit by the processor
what is an I/O controller
a device which interfaces between an input or output device and the processor
what is the controller and what does it consist of
- an interface that allows connection of the controller to the system
- a set of data, command and status registers
- an interface that enables connection of the controller to the cable connecting the device to the computer
what is an interface
a standardised form of connection defining things like signals
examples of control signals
memory writes, reads, interrupt requests, clock, bus requests and grants
what does the data bus transfer
data and instructions
how does word length affect CPU performance
word length defines the amount of data a CPU can process at one time
- larger word lengths allow for processing larger chunks of data in a single cycle
how does bus width affect CPU performance
address bus - the max memory address that can be transmitted is 2^n - 1 , higher width = more memory location accessed
data bus - width of data bus tells us how many bits can be transferred simultaneously , larger width means more bits of data can be moved simultaneously
why is translation necessary
because the processor can only execute machine code instructions
explain why an instruction on couldn’t be processed directly from the MBR
- during the execute stage, MBR is used to store other data
- MBR is not wired to the components that’ll execute the instruction
Describe:
* what cache memory is
* what cache memory is used for
* how increasing the amount of cache memory can improve the performance of a
processor.
- Memory that can be accessed very quickly;
- Memory located on the processor
What cache memory is used for:
- To store most frequently used data
How more cache memory improves performance:
- More data can be stored in the cache;
-data stored in cache can be accessed more quickly than data in main memory
- this increases the probability of a cache hit
