A1 Computer fundamentals - Computer hardware and operation

Vocabulary flashcards covering CPU structure, memory hierarchy, buses, processing concepts, storage, compression, and cloud services.

CPU

Central Processing Unit; the engine of a computer that executes instructions and coordinates data movement, containing components like the ALU, CU, registers and buses.

ALU

Arithmetic Logic Unit; performs arithmetic and logical operations.

Control Unit (CU)

Orchestrates the fetch-decode-execute cycle, decodes instructions, and generates control signals to activate the appropriate hardware.

Instruction Register (IR)

Holds the current instruction being executed.

Program Counter (PC)

Stores the address of the next instruction to be executed and increments after each instruction.

Memory Address Register (MAR)

Stores the memory address of the data or instruction to be accessed.

Memory Data Register (MDR)

Holds the data or instruction that is being transferred to or from primary memory.

Accumulator (AC)

Special-purpose register used to store intermediate results in arithmetic and logical operations.

Bus

A shared communication pathway that transfers data between CPU components and other parts of the system.

Data bus

Pathway for transferring actual data; bidirectional; width influences transfer speed.

Address bus

Pathway carrying memory addresses from the CPU to memory to specify where data should be read or written.

Control bus

Pathway carrying control signals (read/write/acknowledge, etc.) and timing information.

Single-core processor

CPU with one processing core; executes one instruction at a time and has limited parallelism.

Multi-core processor

CPU with two or more processing cores on a single chip; enables parallel processing and better multitasking.

Co-processor

Specialized processor that supplements the CPU by offloading specific tasks (e.g., GPU, DSP) to boost performance.

GPU

Graphics Processing Unit; highly parallel processor with thousands of cores optimized for graphics rendering and increasingly for ML workloads.

Parallel processing

Executing multiple tasks or parts of a task simultaneously to improve performance.

SIMD

Single Instruction, Multiple Data; same instruction applied to many data elements in parallel.

Instruction Set Architecture (ISA)

The set of commands a processor can understand and execute; defines supported operations and addressing.

Cache

High-speed memory levels (L1, L2, L3) close to the CPU to reduce latency and speed up data access.

L1 cache

Closest to the CPU; fastest and smallest cache level.

L2 cache

Second-level cache; larger and slower than L1 but faster than RAM.

L3 cache

Shareable cache across cores; largest and slower than L2 but faster than main memory.

Cache hit

When the required data is found in a cache, enabling very fast access.

Cache miss

When data is not found in cache, requiring fetch from lower memory levels.

RAM

Main memory; volatile workspace for the CPU that holds active OS, applications and data.

ROM

Non-volatile memory storing firmware/BIOS; not used for day-to-day memory access but essential for startup.

Registers

Small, fast storage locations inside the CPU used to hold data, addresses, instructions and intermediate results.

Pipelining

A technique to improve performance by dividing execution into stages that can operate concurrently.

Fetch-decode-execute cycle

The basic instruction cycle: fetch an instruction from memory, decode it, and execute it; repeated for each instruction.

Memory hierarchy

Arrangement of memory from fast, small to slow, large (registers → L1/L2/L3 caches → RAM → storage) to optimize speed and efficiency.

Secondary memory storage

Non-volatile storage used for long-term data retention (e.g., HDDs, SSDs, optical discs, flash drives, NAS).

HDD

Hard Disk Drive; magnetic storage with large capacity but relatively slow access.

SSD

Solid State Drive; NAND flash storage with no moving parts, offering fast access and lower latency.

eMMC

Embedded Multimedia Card; flash storage used in mobile devices; slower and lower capacity than SSDs.

External storage

External HDDs/SSDs connected via USB/Thunderbolt for portable or additional storage.

Optical drive

Drive that reads/writes optical discs (CD/DVD/Blu-ray); high capacity but slower access and fragile discs.

Flash drive

USB flash drive; portable NAND memory for transferring small to medium files.

NAS

Network Attached Storage; centralized network storage with shared access and usually RAID for redundancy.

Compression

Process of reducing data size to save storage/bandwidth; can be lossless or lossy.

Lossless compression

Preserves original data; decompressed data matches the original; examples include GIF, TIFF, PNG, ZIP.

Lossy compression

Sacrifices some data to achieve higher compression; used in images, audio, video (e.g., JPEG, MP3).

Run-length Encoding (RLE)

Lossless compression that encodes consecutive runs of the same value as a count and symbol.

Transform coding

Compression using mathematical transforms (e.g., DCT) to exploit data redundancy; used in JPEG, MP3.

Cloud computing

Accessing computing resources over the internet on a pay-as-you-use basis; resources are centralized in data centers.

SaaS

Software as a Service; software hosted by a provider and accessed via a browser; updates included.

PaaS

Platform as a Service; cloud platform that provides operating systems, databases and tools to develop and deploy applications.

IaaS

Infrastructure as a Service; virtualized computing resources (servers, storage, networking) accessed over the internet; customer manages OS and applications.

DVFS

Dynamic Voltage and Frequency Scaling; adjusts voltage and clock frequency to save power based on workload.

TDP

Thermal Design Power; maximum heat a CPU/GPU is expected to generate under typical loads.

Virtual memory

OS-managed extension of RAM using disk space to create more usable memory space, with slower access.