System architecture Flashcards
what is an embedded system
a small dedicated system that performs specific tasks related to their function within a larger system.
what are the disadvantages of an embedded system
very narrow skill set
three advantages of an embedded system
easier to design, cheaper to produce and more efficient at its task than a general computer
what is the overall purpose of the CPU
to process data and instructions
what three factors effect CPU speed
clock speed, number of cores and cache size
what are the three components that make up the CPU
Control unit, Arithmetic logic unit and cache
what is the function of the control unit
To manage the fetch decode execute cycle and oversee the flow of data in and out of the CPU
what three things are typically closely linked to the CPU
main memory, input and output devices
what is the function of the ALU
It completes all the arithmetic calculations, and performs logic operations
what is the function of the cache
High speed, volatile memory close to the CPU that holds regularly used data
what is the function of the program counter
Holds the address of the next instruction for each cycle
what is the purpose of the MAR
hold the address of the instruction the CPU is about to use
what is the purpose of the MDR
To hold the actual data, ready to be written into memory or already fetched from memory
what is the purpose of the accumalator
To store the results of calculations made by the ALU
what happens in the fetch part of the fetch-decode-execute cycle
“Memory address is copied from PC to MAR, and then the instruction goes to the MDR. PC is then increased
to point to the address of the next instruction of the cycle
“
what happens in the decode section of the fetch-decode-execute cycle
Instruction in the MDR is decoded by the CU
Two characteristics of RAM
High speed, volatile.
what is the main function of RAM
It is where all the data and programs are stored whilst they’re being used
What happens when an application is opened on a computer
It is copied from the secondary storage to the RAM
what is primary storage
Mostly volatile storage that the CPU can access quickly. Fast read/write speeds compared to secondary storage
What is secondary storage
Non volatile memory, where all data is stored when it is not in use
What is virtual memory
It is secondary storage used as extra RAM for when the real RAM is overrun
Three disadvantages of virtual memory
Makes computer slower to respond. Inefficient. Takes longer to read and write.
What is ROM
read only, non volatile memory that holds the BIOS which tells the computer how to boot up
What are the three types of secondary storage
solid state drive, optical memory and magnetic
rank the three type of secondary storage based on speed
optical, magnetic, ssd
rank the three type of secondary storage based on capacity
optical, ssd, magnetic
rank the three type of secondary storage based on cost
magnetic, optical, ssd
rank the three type of secondary storage based on portability
magnetic, optical, ssd
