[MUSIC PLAYING]
SPEAKER 1: What do we mean when we talk about a computer's architecture?
SPEAKER 2: That's about what's inside a computer.
John von Neumann was part of a group of people
who created a model that describes the insides of a computer.
He was a physicist and mathematician born in 1903 in Budapest, Hungary.
The von Neumann architecture, used in all modern computers,
is named after him.
There still exists a controversy around the naming of this architecture,
however.
John William Mauchly and John Eckert used this concept already in their work
on the big ENIAC computer.
To give a good tribute to everyone, we speak about the Princeton architecture.
This keeps everyone happy.
SPEAKER 1: This computer architecture is an abstract model
that splits a computer into four distinct parts.
The first part is the arithmetic logic unit, also called ALU.
Its role is to perform basic operations, such as plus, minus, times,
division, as well as logical operations, such as and, or, and not.
The second part is the control unit that coordinates the operation
and sequence of data movements between the other parts of the architecture.
Here's an example.
Imagine we wanted to add two numbers stored in memory.
The following sequence of operations will accomplish this task
if it is performed in the given order.
The timing of such a sequence of operations
is crucial and is dictated by the control unit.
Read the first value from memory.
Read the second value from memory.
Add the two values.
Store the result of the addition back in memory.
Together, the arithmetic logic unit and the control unit
form the so-called central processing unit, or CPU, of the computer.
SPEAKER 2: The third part is the computer's memory.
It serves both data and programs.
Memory comes in two flavors, temporary memory,
also called RAM, short for random access memory,
and lasting memory, such as hard drives.
The final part of the Princeton architecture model
consists of the computer's input and output.
This enables communication between the computer and the external world,
such as the user, peripherals, and even other computers.
SPEAKER 1: Most computers conceived of between the 1940s
and the early 1970s were designed according to this model.
As computers started evolving more rapidly in the 1970s,
new ideas emerged.
For example, computer memory can now communicate directly
with input and output, bypassing the CPU entirely.
But let's keep it simple for now.
The architecture we just described provides a good if somewhat simplified
overview of what are still the main concepts in modern computer information
technology.