Flashcards · 9618 · A Level Topic 15

Hardware and Virtual Machines (A Level) flashcards

10 cards on A Level Topic 15, subtopics 15.1 to 15.2. Pick a subtopic or study them all.

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What is the difference between RISC and CISC processors?: RISC: a small set of simple instructions, each taking one clock cycle; more general-purpose registers; suits pipelining. CISC: many complex instructions, some taking several cycles; shorter programs.
What is pipelining?: Different stages of several instructions (fetch, decode, execute …) are carried out at the same time, one stage per instruction, so more instructions complete per unit time.
What are SISD, SIMD, MISD and MIMD?: Basic computer architectures: Single/Multiple Instruction stream with Single/Multiple Data stream. SIMD applies one instruction to many data items at once (e.g. graphics); MIMD has processors running different instructions on different data.
What is a massively parallel computer?: A large number of processors working together on the same problem, each with its own memory, linked by a network.
What is a virtual machine? Give a benefit and a drawback.: Software that emulates a computer, so one system can run another operating system as a guest. Benefit: run software for another platform or test safely. Drawback: slower than running directly on the hardware.

What are De Morgan’s laws?: NOT (A AND B) = (NOT A) OR (NOT B) NOT (A OR B) = (NOT A) AND (NOT B)
What does a half adder do?: Adds two bits, A and B. Sum = A XOR B; Carry = A AND B.
What does a full adder do?: Adds two bits and a carry-in, giving a sum and a carry-out. It can be built from two half adders and an OR gate; full adders are chained to add multi-bit numbers.
What is a flip-flop?: A sequential circuit that stores one bit: its output depends on its inputs and its previous state. SR and JK flip-flops are used in memory and registers.
What is a Karnaugh map used for?: Simplifying a Boolean expression: 1s are placed in a grid labelled in Gray code order, and adjacent groups of 1, 2, 4 or 8 are combined to remove variables.