Computer Architecture and Operating Systems Overview

CPU

Does logical and mathematical calculations and manages memory. Contains the ALU and CU.

ALU

Holds the accumulator register and does arithmetic and logical calculations in the CPU.

CU

Decodes instructions and instructs other parts to carry out the instructions.

Registers

Small amounts of memory which hold a word of data and carry out a specific function (e.g., accumulator, SCR sequence control, CIR current instruction).

Primary Memory

The main memory which is used to store instructions in binary.

Cache Memory

Another form of primary memory which is faster than normal RAM since data travels a shorter distance.

Machine Instruction Cycle

The cycle is Fetch, decode, execute, store, and repeat if needed. This cycle allows the CPU to carry out every instruction it receives.

Persistent Storage

Used to store information which does not have to be in use in the current moment, which the RAM usually handles.

Operating System (OS)

Uses programs to manage all activities of a computer system including access control, accounting, error handling, I/O, interrupt handling, JCL interpretation, job sequencing, protection/security, resources allocation, and memory management.

Application Software

Allows users to have a wide range of possible features they can accomplish.

Common Features of Applications

Applications can be for entertainment like games or video players, for writing on digital documents, or for creativity allowing editing and drawing.

Bit

Stands for binary digit. Smallest possible data size.

Byte

A unit of digital information that consists of 8 bits.

Binary

Counting system in base 2.

Decimal

Counting system in base 10.

Hexadecimal

Counting system in base 16.

Data Representation

Data is represented in zeros and ones, or binary. Zero means false, one means true.

AND (Boolean Operator)

If both are true, the result is true. Otherwise, it's false.

OR (Boolean Operator)

If any is true, it is true. Otherwise, it's false.

NOT (Boolean Operator)

Switches the boolean value of a single operand.

NAND (Boolean Operator)

Gives opposite value of AND.

NOR (Boolean Operator)

Gives opposite value of OR.

XOR (Boolean Operator)

Returns true if the operands contain different values. Otherwise, it's false.

Data Movement in CPU

Data is able to move around between different parts of the CPU using buses.

Truth Table

A table used to determine the truth value of a logical expression based on its variables.

Logic Diagram

A graphical representation of a logical operation using gates like AND, OR, NOT, NAND, NOR, and XOR.

Buses

Communication systems that transfer data between components of a computer.

Operating System

A collection of programs that manage and handle all computer activity.

CISC

Complex instruction set computer.

RISC

Reduced instruction set computer.

SIMMS

Single inline memory modules used in expansion slots.

Cache

A smaller section of RAM in powerful computers that allows simultaneous reading and writing.

Level 1 Cache

Cache located on the microprocessor.

Level 2 Cache

Cache located between main memory and the processor.

VRAM

Memory in the video card used for graphics.

Mainframe and Minicomputers

Multiuser machines that run multi-programming.

Micro-computers

Personal computers used by one person, may not run a multitasking OS.

Batch Mode

An older OS mode where jobs are queued and executed one by one.

JCL

Job control language used for executing jobs in batch mode.

Real-time Operating System

An OS that processes outputs affecting inputs, like airline control.

Access Control

Management of who can access and perform actions in a system.

Utilities

Services provided as parts of an OS, such as formatting and backups.

Tokens

Compressed representations of common words or combinations in programming.

Viruses

Computer programs that replicate themselves and may have a payload.

Linker

A tool that joins several modules and calls a loader to create an executable.

Executable

A module generated by a linker that is deleted after creation.

Analog Data

Continuous data represented in a predictable manner.

Digital Data

Data represented with discrete numerical values.

Analog to Digital Converter (ADC)

Device that converts analog signals to digital values.

Digital to Analog Converter (DAC)

Device that converts digital signals back to analog.

Kilobyte (K)

1024 bytes, approximately one page of text.

Megabyte (MB)

1,048,576 bytes, approximately the size of a book.

Gigabyte (GB)

A larger unit of digital information, many bytes.

Computer software

Everything (data + instructions) are stored thru patterns of binary digits, which must represent things other than numbers

ASCII

stores data in 8 bits. typing on keyboard --> binary ASCII --> computer's keyboard controller

UNICODE

international standard for representing digits/numbers/letters across programs and systems

bitmap graphics

graphics are stored as a bitmap image divided into a grid of tiny square pixels

one pixel (black and white)

one bit

24 bits (three bytes)

up to 16.7 million colors (true color)

colour bitmaps

use more than one bit per pixel. 8 can define 256 colors. defined using red, green, and blue values (RGB)

frame buffer

section of the video memory where values are put after interpreting bitmap file

vector graphics

graphics made of individual graphics stored as mathematical calculations

compression

when graphics sizes are shrunk using special compression algorithms (like jpg, or gif, etc)

jagged edges

typically seen in raster graphics when zoomed in

cleaner lines

are characteristics of vector objects

header

the info in the file's header are looked at first

signature

identifies the file as a bitmap like .bmp (bitmap)

palette

two colors in a bitmap example

Width 11 px

an example dimension of a bitmap

Height 11 px

another example dimension of a bitmap