CPU & friends
What does the Program Counter (PC) hold?
The memory address of the next instruction.
Is RAM volatile or non-volatile?
Volatile.
What are the 3 stages of the instruction cycle?
Fetch, Decode, Execute.
Give one example of external storage.
USB, external HDD/SSD, SD card.
Why is compression important?
Saves space, speeds transfer.
What does the MAR store, and how does it interact with memory?
Holds address of data/instruction; sends it via the address bus to RAM.
What is stored in ROM?
BIOS/firmware for startup.
What does the MDR do in the fetch stage?
Holds instruction/data fetched from RAM.
What does NAS stand for? Is it internal or external?
Network Attached Storage.
Lossy vs Lossless compression?
Lossless = no data lost; Lossy = data lost, smaller files.
What is the purpose of the Instruction Register (IR)?
Temporarily stores the current instruction before decoding.
What is a cache hit vs a cache miss?
Hit = found in cache; miss = must fetch from slower memory.
Why is the instruction cycle vital for all computer operations?
Every program runs through it billions of times/sec.
Compare SSD vs HDD speed.
SSDs are faster (2,500–7,000 MB/s vs 100–200 MB/s).
What is SaaS? Give an example.
Software as a Service, apps over the internet.
fill in the blank: The _______ holds the intermediate results of the currently running instructions.
Accumulator.
Compare registers, cache, and RAM in speed & size & distance from CPU
Registers fastest/smallest/inside CPU, cache very fast (L1 is on the CPU, L2&3 are close), RAM larger/slower, farthest from CPU
Why does pipelining improve CPU performance?
Allows overlap of fetch, decode, and execute stages.
Why are optical drives becoming obsolete?
Low capacity, slow, streaming/cloud replacing them.
How does PaaS differ from IaaS?
PaaS Provider manages OS/environment, and IaaS gives raw infrastructure only.
Why is GPU architecture better for machine learning than CPU?
Thousands of cores optimized for parallel matrix operations vs a few CPU cores for sequential tasks.
Why does virtual memory slow down performance?
Uses HDD/SSD, which is slower than RAM.
Walk through the fetch–decode–execute cycle step by step, naming the registers and buses involved.
PC → MAR (address placed on address bus) → RAM → MDR (data via data bus) → IR (instruction stored) → CU decodes → ALU/CU executes → result stored in register or memory.
Why is NAS more expensive but beneficial than local drives?
Provides RAID protection, remote access, scalable storage.
Why is elasticity important in cloud computing?
Scale resources up/down instantly, cost-efficient.