Computer Architecture vs Organization

Study Notes

Architecture refers to the attributes of a computer visible to the programmer, such as the instruction set, data types, and memory addressing techniques.
Organization pertains to the hardware details hidden from the programmer, including control signals, peripheral interfaces, and memory technology.
The distinction between architecture and organization is crucial for understanding computer system design and evolution.

Instruction Set: The set of commands the computer understands and can execute.
Data Types: The types of data a computer can represent like numbers, characters, and booleans.
I/O Mechanisms: How the computer interacts with external devices such as keyboards, displays, and storage.
Memory Addressing: Techniques used to access specific locations in memory.

Control Signals: Signals used to coordinate the operation of different components within the computer.
Peripheral Interfaces: Connections and protocols for communicating with external devices.
Memory Technology: The specific type of memory used in the system, such as DRAM or SRAM

First Generation: Vacuum tube-based computers, large, expensive, and prone to failure.
Second Generation: Transistor-based computers, smaller, more reliable, and less power-consuming than their predecessors.
Third Generation: Integrated circuit-based computers, characterized by miniaturization, greater processing power, and lower costs.

Main Memory: Stores both data and instructions.
Arithmetic and Logic Unit (ALU): Performs arithmetic and logical operations on binary data.
Control Unit: Interprets instructions and directs the flow of data.
Input/Output (I/O): Handles communication with external devices.

A landmark computer design that served as a foundation for many subsequent machines.
Utilizes the von Neumann architecture, where instructions and data are stored in the same memory space.
Contains essential components such as a memory buffer register (MBR), a memory address register (MAR), an instruction register (IR), an instruction buffer register (IBR), a program counter (PC), an accumulator (AC), and a multiplier quotient (MQ).

Each instruction cycle consists of two subcycles: the fetch cycle and the execution cycle.
In the fetch cycle, the next instruction's opcode is loaded into the IR and the address portion is loaded into the MAR.
The instruction is then fetched from memory, either directly from the IBR or by loading a word into the MBR and then transferring it to the IBR, IR, and MAR.
The execution cycle executes the fetched instruction.

Early Computers: Split into two categories: scientific machines focused on complex calculations and business machines designed for large-scale data processing.
IBM's Role: Emerged as a dominant computer manufacturer, introducing the 701 (scientific) and 702 (business) models, marking the beginning of a long series of 700/7000 computers.
Second Generation: The invention of the transistor led to smaller, faster, and more reliable computers.
Third Generation: The integration of circuits enabled the creation of even smaller and more powerful computers.
Microprocessors: Introduced by Intel, revolutionized computing by integrating all the necessary components on a single chip.