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Lectures
Lecture 01 Template
01 - Intro to Operating Systems
Outline
Reading: MOS 1.1
What is an OS?
1)
2)
3)
4)
Where does the OS fit in?
Short answer:
A software abstraction layer and resource manager.
First, what does the OS fit into?
Let's look at a relatively simple computer.
A Raspberry Pi.
Usually you use multiple applications or programs
running in a User Interface (UI).
It would be prohibitively difficult for applications
to manage hardware directly:
- domain knowledge
- resource contention
- trust
The operating system provides an API that
programs can use to access hardware capabilities
without needing to manage hardware components
directly.
We've already identified 2:
> Abstraction of hardware (extended machine)
- Ex: file systems to access disk memory
- Hide the ugly from application programmers
> Management of hardware (resource manager)
- Enable concurrency/parallelism
- Memory + I/O management/protection
- Multiplex (share) resources in time and space
Additionally:
> Security
- Enforce access control
- Process isolation
It's not the UI alone.
This course focuses on the kernel.
System Stack:
Even though it so small, there's a lot going on.
We need to take all this hardware and turn it into
something useable.
Every component requires non-trivial code to be
managed correctly.
- Dedicated hardware controllers help, but
aren't a replacement.
And that's peanuts compared to a full mainboard.
This one is from ~2005.
Now they look all space-y.
Some examples you may be familiar with:
- Windows
- macOS
- Linux
- Debian
- Ubuntu
- Arch Linux
- Android
- Kali Linux
- too many...
Some examples you may not be familiar with:
- Minix
- Multics
- OpenSolaris
- illumos
- BSD
- FreeBSD
- OpenBSD
- NetBSD
- VxWorks
- ZephyrOS
- FreeRTOS
- QNX
What are its main functions?
What is considered an OS?
What is an OS?
Where does the OS fit in?
GPIO, SPI, I2C, UART, SDA, PWM, ...
USB
DSI Display
CSI Camera
Audio
HDMI
Power
BCM 2835
SoC
Ethernet
Controller
Text UI (TUI)
Graphical UI (GUI)
User Interface
Browser
Terminal
Editor
Operating System
Hardware
Software
MOS Figure 1-1
What are its main functions?
What is considered an OS?
UIs
Raspi 3 Diagram
asrock k7vt4a pro mainboard
gigabyte x570 elite mainboard
Hardware
Application
Hypervisor/VM monitor
Core Runtime Libraries
User Interface
Compiler
Runtime Libraries
Kernel
Kernel
Extension
Kernel
Extension
OS
System
Software
Kernel Mode
(privileged)
User Mode
(unprivileged)
system stack