Maharashtra HSC Computer Technology (Vocational) key terms

A computer design in which one memory holds both program instructions and data, and the CPU fetches, decodes and executes instructions one at a time through a shared bus.

The central processing unit that fetches instructions from memory, decodes them and carries out arithmetic, logical and control operations. It contains the ALU, control unit and registers.

The arithmetic logic unit inside the CPU performs integer arithmetic such as addition and subtraction, plus logical operations such as AND, OR, NOT and comparisons on binary operands.

The CPU section that reads each instruction, decodes its operation code, and generates timing and control signals that make other units carry out the required steps.

A very small, very fast storage location inside the CPU used to hold operands, addresses or intermediate results during instruction execution. Examples include the accumulator and program counter.

Fast semiconductor storage directly addressable by the CPU, such as RAM and ROM, holding programs and data currently in use. It is volatile in the RAM case and smaller than secondary storage.

Random access memory is read-write volatile primary storage whose contents are lost when power is removed. It holds the operating system, running programs and working data.

Read-only memory is non-volatile primary storage written during manufacture or by special equipment. It keeps firmware such as the bootstrap loader available every time the computer starts.

A small high-speed memory placed between the CPU and main memory that keeps recently used instructions and data, reducing average access time caused by the speed gap between processor and RAM.

A set of parallel conductors that carries data, addresses and control signals between the CPU, memory and input/output devices. Width and clock speed strongly affect performance.

The repeating sequence of fetching an instruction from memory, decoding it, executing the operation and storing any result, after which the next instruction is fetched.

System software that manages hardware resources, schedules processes, allocates memory and storage, and provides services and a user interface so application programs can run.

A program in execution together with its current state, program counter, registers and allocated resources. The operating system creates, schedules and terminates processes.

A technique that lets programs use more address space than physical RAM by keeping inactive pages on disk and swapping them into memory when needed.

The structure an operating system uses to name, store, organise and retrieve files and folders on a storage device, including allocation tables, directories and access permissions.

The textual location of a file or folder in a directory tree. An absolute path starts from the root, while a relative path starts from the current working directory.

The suffix after the final dot in a file name, such as .txt or .jpg, that indicates the file type and usually tells the operating system which application should open it.

Software that lets the operating system communicate with a particular hardware device by translating general commands into the device-specific instructions the hardware understands.

A capability in which the operating system automatically detects newly connected hardware, loads a suitable driver and assigns resources without manual configuration by the user.

A way of writing numbers in which each digit's value depends on its position, multiplied by a base raised to a power. Decimal, binary, octal and hexadecimal are common examples.

A positional system using only the digits 0 and 1 with base 2. Each position represents a power of two, which suits digital circuits that distinguish two voltage levels.

A positional system with base 16 using digits 0 to 9 and letters A to F. It is used as a compact shorthand for binary because one hex digit represents exactly four bits.

The base of a positional number system, equal to the number of distinct digit symbols used. Decimal has radix ten, binary radix two and octal radix eight.

A signed binary representation formed by inverting every bit of the number. It has two representations of zero and is mainly used as an intermediate step towards 2's complement.

A signed binary representation obtained by adding one to the 1's complement. It has a single zero and lets subtraction be performed as addition, so hardware needs only one adder circuit.

The smallest unit of digital information, holding a single value of either 0 or 1. Groups of bits form bytes, which are commonly eight bits long.

A group of eight bits treated as one unit. It can store one ASCII character or a value from 0 to 255, and storage capacity is usually measured in multiples of bytes.

A branch of algebra in which variables take only the values 0 and 1 and operations are AND, OR and NOT. It gives rules for simplifying and analysing digital logic circuits.

An electronic circuit with one or more binary inputs and one output that performs a basic logical operation such as AND, OR, NOT, NAND, NOR, XOR or XNOR.

A table listing every possible combination of input values for a logic expression or circuit and the resulting output, used to verify or design logic behaviour.

A grid arrangement of truth table outputs used to group adjacent cells and simplify Boolean expressions visually, usually giving a minimal sum-of-products form.

Two Boolean identities stating that the complement of an AND is the OR of the complements, and the complement of an OR is the AND of the complements. They help convert circuits between NAND and NOR forms.

A finite, ordered set of unambiguous steps that solves a problem or produces a result, usually expressed as pseudocode or a flowchart before it is coded.

A diagram that shows the steps of an algorithm using standard symbols such as ovals for start and end, parallelograms for input and output, and diamonds for decisions.

A structured, English-like notation for expressing an algorithm without the strict syntax of a programming language, making the logic easy to read and translate into code.

A programming construct that repeats a block of statements while a condition holds or for a fixed number of times, avoiding duplicated code in an algorithm.

A programming construct that executes one block of statements or another depending on whether a tested condition is true or false, enabling decisions in a program.

The process of translating a complete program written in a high-level language into machine code by a compiler before it is run, producing an executable file.

A translator that reads a program statement by statement, converts each into machine operations and executes it immediately, stopping at the first error it meets.

A mistake in the spelling, punctuation or grammar of a program that violates the rules of the language, detected by the compiler or interpreter before execution.