Computer Science Midterm

Abstraction

A simplified representation of something complex, focusing only on essential details and hiding unnecessary ones.

Layers of a Computing System

The organized structure of computing, typically including hardware, operating system, software, and user interfaces.

High-Level Language

A programming language closer to human language, easier for people to read and write.

Low-Level Language

A language closer to machine code, harder for humans to read but more efficient for computers.

Compiler

A program that converts high-level code into machine code before execution.

Assembler

A program that translates assembly language into machine code.

Transistors vs Vacuum Tubes

Transistors are smaller, faster, and more reliable than vacuum tubes, which were used in early computers.

Bits and Bytes

Bits are binary digits (0 or 1); 8 bits make up one byte.

Bit Representation

Low voltage represents 0, high voltage represents 1.

Binary to Decimal Conversion

Converting base-2 numbers to base-10.

Decimal to Binary Conversion

Converting base-10 numbers to base-2.

Binary to Hexadecimal Conversion

Grouping binary digits into sets of four and converting each group to a hexadecimal value.

Number Systems

Methods of representing numbers (Binary, Decimal, Hexadecimal).

Adding Binary Numbers

Adding digits in base-2 using carry-over rules.

Analog Data

Data represented in a continuous form (e.g., sound waves).

Digital Data

Data represented in discrete binary form.

Two’s Complement

A way of representing signed binary numbers; negative numbers are created by inverting bits and adding 1.

Keyword Encoding

Text compression technique replacing frequently used words with shorter symbols.

Run-Length Encoding

Compression method replacing repeated characters with a count and a single instance.

Compression Ratio

The ratio between the uncompressed size and the compressed size of data.

Representing Color

Using binary combinations to store color information (RGB model).

Representing Text

Encoding letters and symbols into binary (e.g., ASCII, Unicode).

Representing Audio Data

Converting sound waves into binary through sampling.

Logic Gate

A basic building block of digital circuits performing a logical operation.

NOT Gate

Inverts input; outputs the opposite value.

AND Gate

Outputs true only if all inputs are true.

OR Gate

Outputs true if any input is true.

XOR Gate

Outputs true if inputs differ.

NAND Gate

Outputs false only if all inputs are true.

NOR Gate

Outputs true only if all inputs are false.

Boolean Expression

A formula using AND, OR, NOT to describe circuit logic.

Logic Diagram

A visual representation of logic gates in a circuit.

Truth Table

Table showing all input and output combinations for a logic circuit.

Combinational Circuit

A circuit where outputs depend only on current inputs.

Von Neumann Architecture

Computer design with shared memory and instructions/data stored together.

Stored-Program Concept

Instructions are stored in memory and executed sequentially.

Fetch-Execute Cycle

The cycle where a computer retrieves, decodes, and executes instructions.

Types of Memory

Includes RAM, ROM, Cache, and Secondary Storage.

RAM vs ROM

RAM is volatile and temporary; ROM is non-volatile and permanent.

Booting Process

The steps a computer takes to load the operating system on startup.

Instruction Register

Holds the current instruction being executed.

Program Counter

Holds the address of the next instruction to execute.

Operating System

Software that manages hardware, software, and user interaction.

Application Software

Programs that perform specific user tasks (e.g., Word, Excel).

System Software

Software that manages computer resources and operations.

Memory Management

The process of controlling and coordinating computer memory.

Paged Memory Management

Memory divided into fixed-size pages to manage efficiently.

Demand Paging

Loading memory pages only when needed.

Virtual Memory

Technique allowing execution of processes not fully in physical memory.

Thrashing

Excessive paging that slows down system performance.

CPU Scheduling

Determines the order processes are executed by the CPU.

First-Come, First-Served

Processes executed in order of arrival.

Shortest Job Next

The process with the smallest burst time executes first.

Round Robin

Each process is given equal time in cycles.

Average Turnaround Time

The average time it takes for all processes to complete.

Time Sharing

Allowing multiple processes to use CPU resources in rotation.

Address Binding

Mapping logical addresses to physical addresses in memory.

File Types

Categories of files such as text, binary, executable, etc.

Text File

File storing readable characters (ASCII/Unicode).

Binary File

File containing data not meant to be read as text.

Sequential Access

Reading data in a fixed order from beginning to end.

Direct Access

Accessing data directly using an address or index.

Directory Tree

Hierarchical structure of folders and files in a file system.

Seek Time

The time taken by the disk’s read/write head to reach the desired track.

Latency

The delay before data transfer begins after a command is issued.

Disk Scheduling

Technique to determine the order of disk I/O requests.

First-Come, First-Served (Disk)

Requests are processed in arrival order.

Shortest-Seek-Time-First

Chooses the request closest to the current head position.

Scan (Elevator Algorithm)

Disk arm moves back and forth servicing requests in order.

Starvation

When some requests wait indefinitely due to scheduling priorities.

Spreadsheet Basics

Using rows and columns to organize data.

Spreadsheet Formulas

Expressions that calculate values automatically.

Circular Reference

When a formula refers to its own cell directly or indirectly.

Database

A structured collection of data stored electronically.

DBMS

Database Management System; software to manage databases.

Select Query

SQL command used to retrieve data from a database.

Primary Key

A unique identifier for a record in a table.

Foreign Key

A field linking one table’s primary key to another table.

Entity-Relationship

Model showing relationships between database entities.

Machine Language

The lowest-level programming language understood by computers.

Assembly Language

Low-level language using mnemonic codes instead of binary.

High-Level Language

Programming languages closer to human language.

Assembler

Converts assembly language into machine code.

Compiler

Translates high-level language into machine code.

Pseudo Code

Informal code outline used to design algorithms.

Flow Chart

Diagram representing process flow using symbols.

Pep9 Simulator

Tool to practice writing machine code instructions.