Computing 1.1 systems architecture Flashcards
CPU
The main part of the computer which is sometimes called the BRAIN that consists of the registers, ALU and control unit.
Vonn Neumann Architecture
Computer architecture that forms the basis of most digital computer systems.
Cache
Faster access memory for frequently used instructions and data.
Fetch- Decode- Execute Cycle
The process of retrieving an instruction from the store, decoding it and carrying it out.
Registers
Superfast onboard memory that each have a specific purpose: MAR, MDR,PC and ACC.
MAR(Memory Address Register)
Holds the address of the data/instruction to be used/passed from the program counter. PART OF THE DECODE CYCLE
MDR(Memory Data Register)
Holds the data fetched or to be written to the memory. PART OF THE EXECUTE CYCLE
PC(Program Counter)
Holds the address of the next instruction to be executed. PART OF THE FETCH CYCLE
ACC(Accumulator)
Hold the RESULT of the calculation
What main factors affect the performance of the CPUs performance? (3 things)
The clock speed, cache size and the number of cores.
Clock speed
HERTZ(GHz). It’s the number of instruction cycles that can be executed per second.
Cache size
The LARGER the cache, the more that can be copied and stored without having to go back to the RAM(which takes more time to fetch data from). HOWEVER the bigger it is the slower it is.
Number of Cores
The cores are responsible for the Fetch- execute cycle. The more cores there are, the more cycles that can be done at one time. HOWEVER it takes more time as more communication is needed to take place.
Embedded Systems
is a computer that has been built to solve a specific function. eg. washing machine, microwave, traffic lights…
RAM(Random Access Memory)
RAM is the main memory in that stores the information that your computer is actively using. VOLATILE- data is lost when power is lost.
Virtual Memory
Using part of the hard disk as if it were RAM which allows more applications to be open than physical memory could hold.
What happens in the FETCH cycle?
The PROGRAM COUNTER is loaded with the address of the next instruction. The address is then loaded into the MAR which is then sent to the RAM through the address bus and copied through the data bus to the MDR.
What happens in the DECODE cycle?
In the DECODE cycle the instruction is sent to the CU through the data bus and decoded.
What happens in the EXECUTE cycle?
In the EXECUTE cycle the outcome is stored in the accumulator.
CU (control unit)
Controls how data moves around the CPU.
ALU (Arithmetic Logic Unit)
Performs arithmetic equations and logical comparisons .
ROM (Read Only Memory)
Memory can be read from i but cannot be written into. NONVOLITALE- data is not lost when power is turned off(permanent memory)
