Organization & Architecture
- Computer architecture – those attributes of a system visible to a programmer or, put another way, those attributes that have a direct impact on the logical execution of a program.
- Computer organization – the operational units and their interconnections that realize the architectural specifications
Examples of computer architectural attributes include…
- Instruction set
- The number of bits used to represent various data types
- I/O mechanisms and techniques for addressing memory
Examples of computer organization attributes includes…
- hardware details transparent to the programmer including controls signals
- interfaces between the computer and peripherals
- memory technology used
Computer architecture tends to last decades, while computer organization often operates in a much smaller time frame. For instance, IBM PC architecture has been around for a long time, but the actual organization of the components that make up the architecture is continually changing.
Structure and Function
- Structure – the way in which the components are interrelated
- Functions – the operation of each individual components as part of the structure
Both the structure and functioning of a computer are in essence simple.
Functions
In general terms there are only four…
- Data processing
- Data storage
- Data movement
- Control
Structure
There are four main internal structures of the computer….
- CPU – Central processing unit which controls the operation of the computer and performs its data processing functions, often simply referred to as processor
- Main memory – stores data
- I/O – moves data between the computer and its external environment
- System interconnection – some mechanism that provides for communication among CPU, main memory, and I/O (i.e. a system bus)
The CPU is possibly the most interesting of these 4 components, its major structural components are…
- Control unit – Controls and operation of the CPU and hence the computer
- ALU - Arithmetic and logic unit performs the computer’s data processing functions
- Registers – Provides storage internal to the CPU
- CPU interconnection – some mechanism that provides for communication among the control unit, ALU, and registers