CS Topic 2 - Part 1 & 2

Computer System

consists of hardware and software components and follow the concept of the input, process, output and storage model

other data needed during the processing phase

exists in the storage of the computer system and will be used during the processing phase.

Central Processing Unit

The brain of a computer, responsible for executing instructions and performing calculations

CPU can only access data in the…

primary memory.

Control Unit

Retrieves instructions from memory, decodes them, and controls the flow of data between the CPU and other components

Memory Address Register

Stores the address of the next instruction or data to be fetched or stored in the memory.

Memory Data Register

Storage location that holds the data being read from or written to the computer's memory. Acts as an interface between the memory and the processor, allowing the processor to access and manipulate data stored in memory

Arithmetic Logic Unit

ALU performs arithmetic and logical operations. CU is responsible for providing the ALU with the data and instructions.

Memory Address/Data Bus

The pathway that carries information between the CPU and memory. It consists of address lines for locating data in memory and data lines for transferring the actual data.

Random Access Memory

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Volatile memory for random data access. It stores active data for program execution. MDR transfers data between CPU and RAM.

Read Only Memory

Stores data permanently. Non-volatile. Includes the computer's startup instructions and other essential software. Cannot be modified or written to by normal computer operations.

primary memory

only memory accessible by CPU. Stores in binary. only RAM and ROM

cache memory

Static RAM. Faster, smaller, more expensive. Placed between DRAM and processor. Hold info most often used quickly by the processor.

Machine Instruction Cycle

MEM Fetch → CU Decode → ALU Execute → MEM Store.

1. Fetching instruction

CPU sends the appropriate address through the memory (address) bus to the primary memory. The instruction that resides in the specific address is then copied into the data bus and sent to the control unit (CU).

2. Decoding instruction

Done by CU to allow the CPU to be aware of any additional data that is necessary for the execution of the instruction

3. Execute instruction

ALU executes operations from instruction and calculates a result to store or reprocess with more data

4. Store result and check for next instruction

Result stored in primary memory by finding an address and placing it there

Secondary Memory

Is a relatively slow memory that may be written to but is also non-volatile. Also known as persistent storage.

Virtual Memory

The process of temporarily loading memory from the ROM to secondary memory to create room for more storage

Operating System

set of software that controls the computer’s hardware resources and provides services for computer programs. intermediary between software applications and the computer hardware.

Services of OS

Peripheral Communication

Memory Management

Security

Networking

Resource Monitoring and multitasking

Disk access and data management

Peripheral Communication

Communicating directly with the hardware outside CPU and providing an interface between hardware devices and applications.

Memory Management

How the memory is used by applications and ensuring that one application does not interfere with memory that is being used by another.

Security

Protection of data on computer, commonly done by user authentication. Additional security measure is use of log files that keep track of any user activity in computer system.

Networking

Connections to and interactions with networks of other computer systems so as to allow the sharing of resources. OS is an intermediary between applications and networks.

Resource Monitoring and Multitasking

The allocation of resources so that an application can run effectively. Applications must share the CPU time in order to accomplish their goal. This is known as multitasking and it is a core OS service.

Disk access and data management

Keeping track of files stored in memory and disks, as well as which files are being used by which applications so that an application does not overwrite another applications‘ files.

Software Applications

Type of computer program that performs a specific personal, educational, or business function

Word Processors

Used for the production of any sort of document. It includes tools for the composition, formatting and possibly printing of documents.

Spreadsheets

Used for the organization and analysis of data. The data in spreadsheet application is represented as cells, organized in rows and columns. Can do operations and make graphs.

Database Management System (DBMS)

It manages (creates, queries, updates, stores, modifies, and extracts information) databases and is designed to provide an interface between users and a database.

Web Browser

Used to access, retrieve, and present content on the World Wide Web. Content may be identified by URL (Uniform Resource Locator)

Email

Allows for the exchange of digital messages from a single author to one or more recipient(s).

Computer Aided Design (CAD)

Assists engineers to create, modify, analyze and optimize a design. Purpose is to increase productivity of the designer and the quality of the resulting design.

Graphic Processing Software

Allows user to manipulate visual images on a computer.