Computer Organization and Architecture Topics - GATE CS & IT Syllabus

1

Machine instructions and addressing modes

Instruction format, operand access methods (immediate, direct, indirect, register, indexed, etc.).

1m2/10

📌 Key FormulaEffective address calculation for each mode.

2

ALU

Arithmetic Logic Unit: performs arithmetic and bitwise operations.

2/10

📌 Key FormulaFlags: carry, zero, overflow, sign.

3

Data-path and control unit

Data-path: registers, ALU, buses. Control unit: generates control signals.

2/10

📌 Key FormulaMicroprogrammed vs hardwired control.

4

Instruction pipelining

Overlapping execution of multiple instructions.

1m3/10

📌 Key FormulaSpeedup = number of pipeline stages (ideal).

5

Pipeline hazards

Situations that cause pipeline stalls: data hazards, control hazards, structural hazards.

1m3/10

📌 Key FormulaHazard detection and forwarding.

6

Memory hierarchy

Registers, cache, main memory, secondary storage.

2/10

📌 Key FormulaAverage access time = hit time + miss rate * miss penalty.

7

Cache memory

Small fast memory storing frequently used data.

1m3/10

📌 Key FormulaDirect mapped: block index = (address/block size) % #blocks. LRU replacement.

8

Main memory

RAM: random access memory, usually DRAM.

1/10

📌 Key FormulaMemory latency, bandwidth.

9

Secondary storage

Non-volatile storage: HDD, SSD, etc.

1/10

📌 Key FormulaSeek time, rotational latency, transfer time.

10

I/O interface (interrupt and DMA mode)

Methods for I/O: programmed I/O, interrupt-driven, DMA.

2/10

📌 Key FormulaDMA controller steals bus cycles.