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flashcards for the whole of 1.1 following the specification
purpose of the cpu
to perform the fetch decode execute cycle
what happens at the fetch section of the fde cycle?
causes the next instruction and any data
involved to be fetched from main memory
what happens at the decode section of the fde cycle?
decodes the instruction
what happens at the execute section of the fde cycle?
executes the instruction
explain the F-E cycle step by step
PC → MAR: The Program Counter (PC) sends the address of the next instruction to the Memory Address Register (MAR).
Fetch Instruction: The instruction at the MAR's address is fetched and placed into the Memory Data Register (MDR).
Decode: The Control Unit decodes the instruction and decides if more data is needed.
Fetch Data: If needed, the MAR holds the address of the required data in memory.
Data Fetch: The data is fetched from memory and placed in the MDR for processing.
Von-Neumann architecture
consists of ALU, CU, memory units (eg RAM) and inputs and outputs
both instruction data and program data are stored in the same memory in binary
contains four registers - MDR, MAR, PC and accumulator
ALU
Arithmetic Logic Unit
where the arithmetic operations are done
CU
Control Unit
coordinates and controls all of the activities taking place within the CPU (e.g decoding and executing instructions)
cache
located on the CPU
it is slower to access than registers but faster than RAM
stores frequently accessed data
registers
a very fast memory location in the CPU itself
MAR
Memory Address Register
holds the memory address of the current instruction, and then the data that it uses, so that these can be fetched from memory
MDR
Memory Data Register
holds the actual instruction, and then the data that has been fetched from memory
PC (VNA)
Program Counter
holds the address of the next instruction to be executed
Accumulator
holds the result of an instruction (aka results of arithmetic and logic calculations) before it is transferred to memory
what is the difference between storing data and an address
addresses are stored in the Memory Address Register and data is stored in the Memory Data Register
how does clock speed affect cpu performance?
the faster, the clock speed, the faster instructions are processed = better cpu performance
how does cache size affect cpu performance
larger cache size improves CPU performance by storing more frequently used data, reducing the time needed to access slower main memory.
how does the number of cores affect cpu performance?
more cores allows the computer to complete more tasks at the same time improving cpu performance (quad is better than single core processor)
clock speed
Cycles per second, measured in hertz (Hz)
1Hz = 1 instruction/one cycle carried out a second
number of cores
The number of duplicate processing units (cores) placed in one CPU
embedded system
a single microprocessor that includes RAM, ROM and a CPU
purpose of embedded system
to control the device and to allow a user to interact with it
give 3 examples of embedded systems
dishwashers
smart phones
microwave ovens
digital cameras
smart thermostats
characteristics of embedded systems
typically slow cpu speed
software has one purpose
cannot install new software
programs stored on the ROM
typically very reliable (only programmed to do one thing)
