systems architecture and memory and storage Flashcards
(17 cards)
what happens at each stage of the CPU’s FDE cycle (4)
1)An instruction is fetched from memory and is transferred to the MDR.
2)The instruction is then decoded/understood by the CU.
3)The instruction is then executed/carried out (e.g. ALU).
4)The process is repeated, and the program counter is incremented each time.
1Ghz means it can run 1 billion FDE cycles/second.
CPU 4 components
1) CU - controls the flow of data in the CPU, decodes instructions, and runs the FDE cycle.
2) Arithmetic Logic Unit (ALU) - performs the arithmetic and logic calculations.
3) Cache – stores frequently used data/instructions and is faster than RAM (quick access for CPU).
4) Registers – temporarily holds specific pieces of data needed by the CPU (super-quick access).
what are embedded systems meaning and 2 pros 1 con
a computer system thats built into another device.
o Specialised hardware and software designed to perform a specific function.
o Very limited functions that are difficult to change.
o Easy to design, cheap to produce, and efficient at doing their task.
clock speed meaning and what does it mean if it’s faster
The number of instructions a single processor core can carry out per second (Hz).
program runs faster
what does a more number of cores mean
The more cores a CPU has, the greater the number of instructions it can process in a given space of time.
Each processor can execute a separate instruction at the same time which enables multitasking.
cache size capacity and how can it be negative and example
Caches have very low capacity and are expensive.
Too much cache can be negative as it will take longer to find instructions.
L1 is quickest but has lowest capacity, L3 is slowest but has highest capacity.
embedded systems examples
Washing Machines, Dishwashers, SatNav, Microwaves, Telephones.
CPU’s clock speed and what does it mean when clock speed is faster
CPU’s usually have clock speeds of up to 4GHz.
number of infatuations the cpu can carry out per second
The faster the clock speed, the faster the program runs.
primary storage meaning and examples
Stores data that the processor needs to access e.g. Operating System.
ROM – non-volatile, stores the BIOS (so the computer can start up)
RAM – volatile and stores data/instructions currently being used.
Cache – stores frequently used data/instructions and is faster than RAM (quick access).
Virtual Memory meaning
Secondary storage used as temporary RAM when it is full.
RAM can be filled with new data.
When data is needed, it is moved back into RAM (transfer rates are slow).
Secondary Storage meaning
Stores data/files permanently (non-volatile) even when power is turned off (OS,
Applications, Files etc.).
Stores data/instructions currently not being used.
Solid State (Flash Memory)
examples, access time, portability, durability, capacity and cost and reliability
Solid State (Flash Memory):
SSDs, USB Sticks, SD Cards.
Fastest access/read + write speeds.
Small, light, and portable.
Silent.
Reliable and durable.
No moving parts.
Average capacity.
Highest purchase cost.
magnetic and examples, speed, portability, durability, capacity and cost and reliability
HDDs, Magnetic Tapes.
Largest storage capacity.
Lowest purchase cost.
Reliable.
Average read + write speeds.
Not portable or durable (has moving parts).
optical and examples, time, portability, durability, capacity and cost and reliability
Optical Discs (CD, DVD, Blu-Ray).
Small and portable.
Small cost per GB.
Not durable, easily scratched/damaged while being moved.
Small storage capacity.
Slow read + write speeds
Unreliable.
what does the accumulator do
stores results of calculations.
MAR and MDR meaning
Memory Address Register (MAR) - stores the address of the data to be fetched from, or where it is to be stored.
Memory Data Register (MDR) - stores the actual data/instruction which has been fetched from or is waiting to be written to main memory (RAM).
what does the PC do
stores the memory address of the next instruction for each cycle and is incremented by 1 each time.
