cpu functions/components Flashcards
What is address bus?
it carries memory addresses that identify where data is being read from or written to
What is data bus?
carries the binary 1s and 0s, make up actual info being transmitted around CPU/Computer
What is control bus?
carries commands and control signals to and from every component of CPU
What is OPCODE?
OPCODE = what action needs to be done to the OPERAND, ADD
What is OPERAND?
OPERAND = data needs to be affected by OPCODE
What is control unit?
CU coordinates all activities of CPU. Directs flow of data between CPU and other devices. accepts instruction, decodes it, executes it and stores results in memory/registers. Controls signals like bus requests or grants
What is arithmetic logic unit?
performs arithmetic and logic operations. use general-purpose registers to tempo hold results of calculations like accumulator
what is accumulator?
acc stores the data/control information. the more general-purpose registers a processor has, the faster it may operate. stores results from alu
what is accumulator?
acc stores the data/control information. the more general-purpose registers a processor has, the faster it may operate. stores results from alu
what is memory address register?
mar holds address of next memory location to be fetched. Sends the addresses to memory thro address bus
what is memory data register?
mdr tempo stores data written to or read from memory. all data to/from memory must travel down with data bus and pass through mdr
what is current instruction register?
cir holds current instruction being executed. contents of mdr copied to cir if told so. contains opcode and operand. opcode + operand = instruction
what is the program counter?
pc holds address of next instruction to be executed. at start of fe-de-ex cycle, address held in pc is copied to mar
what is decode unit?
du is logic that is presented with a sequence of bits that have been fetched from memory. prepares execution of an instruction by looking up binary operation code in its table so the CPU knows what to do
what is cache?
cache is small memory located on or near CPU. very fast to instant access frequently used for instructions and data. but its very small.
3 levels: 1 - smallest and fastest, part of the CPU. 2 and 3 - bigger sections built in between CPU and RAM with slower access times, bigger capacity
