Computer Architecture: Von Neumann and Harvard

Study Notes

Von Neumann Architecture is a digital computer architecture that stores program data and instruction data in the same memory.
It was designed by John Von Neumann in 1945 and is also known as sequential architecture, stored program concept architecture, or Princeton architecture.
In Von Neumann Architecture, the same physical memory address is used for instructions and data, and there is a common bus for data and instruction transfer.
It requires two clock cycles to execute a single instruction, and the CPU cannot access instructions and read/write at the same time.

Harvard Architecture is a digital computer architecture that uses separate storage and separate buses for instruction and data.
It was developed to overcome the bottleneck of Von Neumann Architecture and is used in microcontrollers and signal processing.
In Harvard Architecture, separate physical memory addresses are used for instructions and data, and separate buses are used for transferring data and instruction.
It can execute an instruction in a single cycle, and the CPU can access instructions and read/write at the same time.

Von Neumann Architecture is older and cheaper, while Harvard Architecture is modern and more expensive.
Von Neumann Architecture is used in modern computers (personal computers and small computers), while Harvard Architecture is used in microcontrollers and signal processing.

An Operating System (OS) is an interface between a computer and computer hardware that manages hardware resources and provides common services for computer programs.
The goals of an Operating System include security, control over system performance, job accounting, error detecting aids, and coordination between other software and users.
Examples of Operating Systems include eCOS, TinyOS, Symbian, MS-DOS, Windows, Unices, Pre-X MacOS, BeOS, RiscOS, and AmigOS.

The bootstrap process is the process of starting up a computer and initializing the Operating System (OS) during start-up.
A bootstrap program is a smaller program that executes a larger program such as the OS.

Batch Operating System: users do not interact with the computer directly, and jobs with similar needs are batched together and run as a group.
Example: IBM’s OS360.