COMPUTER SCIENCE A

• A computer is a general purpose device that can be programmed to carry out a set of arithmetic or logical operations
• A computer consists of at least one processing element, typically a central processing unit (CPU) and some form of memory
• Computer architecture defines basic attributes of hardware components and their interconnections to achieve specified goals in terms of functions and performance
• Computer organization involves the design and physical arrangement of hardware units to work together in an orderly manner to achieve the goals specified in the architecture
• Computer architecture comprises logical functions like instruction sets, registers, data types, and addressing modes
• Computer organization consists of physical units like circuit design of peripherals and addresses
• Examples of architecture attributes include the instruction set, number of bits to represent data types, I/O mechanisms, and memory addressing techniques
• Organization attributes include hardware details transparent to the programmer, such as control signals, interfaces between the computer and peripherals, and memory technology used
• Computer structure refers to the interrelation of components, while computer function refers to the operation of each individual component as part of the structure
• Functions of a computer include input, storage, processing, output, and control
• A computer consists of components like processor, memory, and I/O that communicate through a bus
• Central processing unit (CPU) is responsible for executing instructions and performing calculations in a computer system
• Main memory, or RAM, provides temporary storage for data and programs actively used by the CPU
• I/O devices enable communication between the computer and the external world for input and output of data
• System bus connects different components within a computer system to enable data, information, and control signal flow
• Data bus transports data and instructions between components bidirectionally
• Address bus sends address signals from the CPU to Main Memory in a single direction
• Control bus sends control signals between components bidirectionally
• The history of computing began with the abacus, followed by the development of programmable digital computers like Mark I
• Computer generations evolved from vacuum tube-based first generation to integrated circuits in the third generation, and VLSI circuits in the fourth generation
• Fifth generation computers use ULSI technology, parallel processing hardware, and AI software
• Programming languages are designed to communicate instructions to a machine
• Used to create programs that control the behavior of a machine
• Types of programming languages:

  • High level
  • Low level
• High level programming languages are more user-friendly and closer to human language
• Low level programming languages are languages that the machine understands
• Types of low level programming languages:

  • Assembly language:
  • Next lowest programming language to machine language
  • Specific to particular computer architecture
  • Source code is converted into executable machine code by an assembler
• Machine language:

  • Lowest level of computer language consisting of binary codes
  • Produced by compiling high-level source code for a specific processor
  • Software developers do not need to manipulate the machine code except for systems' programmers
• Writing an assembly language program requires knowledge of PC hardware and details of various instruction sets
• PC hardware components:

  • Processor
  • Memory
  • I/O
• Connected through a bus, a communication pathway transferring data between the processor, memory, and external devices
• The processor:

  • Responsible for executing instructions and processing data
  • Different processors vary in speed and capacity of memory, registers, and data bus
• System bus:

  • Wires on the motherboard connecting the CPU to other components
• Data bus:

  • Transports data and instructions between components
  • Bi-directional
• Address bus:

  • Sends address signals from the CPU to Main Memory
  • Single-directional
• Control bus:

  • Sends control signals between components
  • Examples: clock signals, interrupt request
  • Bi-directional