1.1: SYSTEMS ARCHITECTURE Flashcards
What is the purpose of the CPU?
To process data and instructions stored in memory by repeatedly carrying out the fetch-decode-execute cycle.
Explain the fetch-decode-execute cycle?
-an instruction is fetched from memory, decoded by the control unit and executed, and the cycle repeats
Functions of the control unit: MAIN POINT and additional ones (4 in total)
- issues control signals that control hardware
- provides timing signals
- fetches, decodes and executes instructions
- moves data around the system
Functions of the Arithmetic Logic Unit: (3)
- performs arithmetic and logical calculations/ operations.
- acts as a gateway between primary memory and secondary storage. Data transferred between them passes through the ALU.
- bit shifts
What are registers and what is their function? (2)
- small amounts of high-speed memory contained within the CPU.
- used by processor to store small amounts of data that are needed during processing
What is the purpose and REASON that cache is important within the CPU? (what does it do, and how does that affect the CPU) (2)
- hold data and instructions that the processor is likely to reuse
- allows for faster processing as the processor does not have to wait for the data and instructions to be fetched from RAM.
What is the purpose of a clock?
used to coordinate all of the computer’s component
How does the clock complete its function?
-sends out a regular electrical pulse which synchronises all the components.
What is the correlation between the clock and clock speed?
The frequency of the pulses is known as the clock speed.
What is a bus and what is its function? (2)
- high-speed internal connection.
- used to send control signals and data between the processor and other components.
program counter:
stores the address of the next instructions to be run (fetched from primary memory), and increments by 1 for every time an instruction is run
memory address register (MAR):
stores the address where the next data will be fetched from
memory data register (MDR):
stores the data that has just been fetched
current instruction register (CIR):
holds the instruction that is currently being decoded and executed
accumulator (ACC):
temporarily stores results by the operations carried out by the ALU
Function of the Address bus:
-carries memory addresses from the processor to other components (such as primary memory and input/output devices)
Function of the Data bus:
carries the actual data between the processor and other components.
Function of the Control bus:
carries control signals from the processor to other components. The control bus also carries the clock’s pulses.
EQ: Identify 2 input devices and one output device that may be connected to the CPU.
Input: keyboard, mouse, scanner, digital camera, microphone, webcam
Output: monitor, printer, speaker
3 factors that affect CPU performance:
clock speed
- cache size
- number of cores
what is clock speed?
-number of fetch-execute cycles per second.
Why is cache memory more efficient than RAM?
- cache memory operates much faster than memory, as data is transferred in and out of cache memory more quickly.
- therefore it makes the CPU more efficient as less time is spent waiting for data to be transferred.
what is clock speed measured in and how does it correlate to the number of instructions?
-clock speed is measured in hertz. The higher the frequency, the more instructions can be performed in any given moment of time.
How will the CPU optimise its use of cache? and for what reason?
- use the fastest cache before using the next level or using RAM.
- in order to improve the performance speed
What is a core capable of doing?
-each core is capable of fetching, decoding and executing its own instructions.
What is the correlation between # of cores and CPU performance?
-the more cores a CPU has, the greater the number of instructions it can process in a given space of time.
What is a possible problem that can be encountered w/ cores?
-the processor may not be able to perform multiple operations simultaneously if the software it is running is not designed for multi-core processors
What is an embedded system?
a small computer that forms part of a larger system, device or machine
Does an embedded system require a full operating system? and why?
-no since they perform limited and very specific tasks
Why must embedded systems be reliable? Explain your answer. (2)
- they cannot be modified once manufactured
- the program that controls them is held in ROM
What is the purpose of an embedded system?
to control the device and to allow a user to interact with it.
Give some examples of embedded systems:
- Traffic lights
- Sound system
- Tumble dryer
- Electronic games
- Digital watches
- Washing machine
- Dish washer
why do embedded system usually have slower clock speed?
-they don’t need to do a lot of processing since they have simple instructions compared to a desktop PC
What is an advantage of using a microcontroller?
- cheaper to manufacture
- fewer components that could go wrong which makes them more reliable
What assumption can you make from the fact that embedded systems often use less power than computer systems? and give an example of how this could be applied to real life.
-they are appropriate for use in small devices in which battery life is a consideration, for example, a smart watch
Characteristics if an embedded system: (3)
- usually have a slower clock speed than desktop computers
- often use microcontrollers- which contain the CPU, RAM & ROM on one chip
- often use less power than computer systems
