Bfh-sts: Created page with "= Hardware & OS: Overview = This page introduces the basic model of a computer and explains how the '''hardware''' and the '''operating system''' interact. It provides the mental map for the following pages. == What is a Computer Built Of? == A computer can be very simple (a microcontroller in an electric toothbrush) or highly complex (a multi-CPU server). In both cases, the core elements are the same: * '''Central Processing Unit (CPU)''': executes instructions (c..."

2025-10-20T13:33:06Z

Created page with "= Hardware & OS: Overview = This page introduces the basic model of a computer and explains how the '''hardware''' and the '''operating system''' interact. It provides the mental map for the following pages. == What is a Computer Built Of? == A computer can be very simple (a microcontroller in an electric toothbrush) or highly complex (a multi-CPU server). In both cases, the core elements are the same: * '''Central Processing Unit (CPU)''': executes instructions (c..."

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= Hardware & OS: Overview =
This page introduces the basic model of a computer and explains how the '''hardware''' and the '''operating system''' interact.
It provides the mental map for the following pages.

== What is a Computer Built Of? ==
A computer can be very simple (a microcontroller in an electric toothbrush) or highly complex (a multi-CPU server).
In both cases, the core elements are the same:

* '''Central Processing Unit (CPU)''': executes instructions (computation, comparison, data movement).
* '''Memory''': stores instructions and data.
* '''Peripherals''': devices for input, output, and storage (keyboard, display, disk, network, USB, …).

:'''Minimal model''' → CPU + memory.
:'''Extended model''' → CPU + memory + peripherals.

== Memory as “Remembered State” ==
The essential feature of memory is to store information until changed.

* Everyday metaphor: a light switch remains on or off until someone flips it.
* In computers: states are represented electrically (voltage = 1, no voltage = 0).
* Changing state = overwriting a previous value.

This idea underlies all later forms of computer memory, from punch cards to DRAM.

== The CPU at a Glance ==
The CPU is often described as the “brain” of the computer. Its core tasks:

* Arithmetic (addition, subtraction, logic).
* Comparisons (greater/less/equal).
* Moving data (load from memory, store to memory).
* Controlling execution flow (jumps, calls).

Modern systems blur boundaries:
A graphics processor (GPU) or a network card may include their own CPUs for specialized tasks.

== Why the Operating System Exists ==
Without an OS, a program would have to:
* Control every piece of hardware directly,
* Handle memory layout itself,
* Decide which program runs when.

The OS solves this by:
* Acting as a '''resource manager''' (CPU time, memory, I/O).
* Providing '''abstractions''' (files, processes, devices).
* Enabling '''multitasking''' and '''multi-user''' operation.

== Putting It Together ==
A working system typically looks like this:

<syntaxhighlight lang='bash'>
[ Peripherals ] ↔ [ CPU ] ↔ [ Memory ]
↑
[ Operating System ]
</syntaxhighlight>

* Hardware provides the raw capabilities.
* The OS organizes and controls access.
* Programs run *on top of* the OS, not directly on the hardware.

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