Fundamentals of computer organisation and architecture flashcards

Topic 7: Fundamentals of computer organisation and architecture

What is the stored program concept?

Machine-code instructions are stored in main memory and are fetched and executed serially by a processor that carries out arithmetic and logical operations.

What is the difference between Von Neumann and Harvard architecture?

Von Neumann: instructions and data share one memory and bus. Harvard: separate memories and buses for instructions and data, so both can be fetched at once; used in embedded systems and digital signal processors.

What do the program counter, MAR, MBR and CIR hold?

PC: address of the next instruction. MAR: address to be read or written. MBR: data or instruction just read or to be written. CIR: the instruction being decoded and executed.

What are the steps of the fetch-execute cycle?

Fetch: copy PC to MAR; read memory into the MBR; increment PC; copy MBR to CIR. Decode: the control unit decodes the opcode. Execute: the instruction is carried out.

What is the difference between immediate and direct addressing?

Immediate: the operand is the value to use. Direct: the operand is the memory address holding the value.

What are the opcode and the operand of an instruction?

The opcode gives the operation (and addressing mode). The operand is the data or address it acts on.

Which factors affect processor performance?

Number of cores, cache memory size, clock speed, word length, and the width of the address and data buses.

How does an RFID tag work?

A reader sends radio waves that power a passive tag’s chip (or an active tag has its own battery); the tag transmits its stored data back to the reader by radio.

How does a solid-state drive store data, compared with a hard disk?

An SSD stores charge in NAND flash memory cells, with no moving parts, so access is faster. A hard disk uses magnetised regions on spinning platters read by a moving head, which is slower but cheaper per gigabyte.