Operating Systems 2014F Lecture 1
Audio from the lecture given on September 5, 2014 is now available.
Notes
Operating System: What is an Operating System? A layer between hardware and your applications.
Real Hardware
- variable, quirks
- they do things differently - abstraction
- most hardware expects a single master - only knows how to take orders from one program. They need to be consistent, not contradict each other.
On a regular computer:
We want:
- portability
- uniformity
- run many programs concurrently
We want to be able to run on multiple systems, and want them to operate in the same way.
The Operating System is what bridges these two sides. Gives you something you live on a regular computer where real hardware acts like this. They do things you can't normally do. They have powers that other programs don't have. Translates the computer you have, and outputs the computer you want to program.
What style of government does an operating system impose? An absolute dictatorship - highly authoritarian.
Von Newmann architecture - pioneer computer science (Turing's Cathedral - Book)
process - key abstraction behind an operating system - they are logically running at the same time.
Moore's Law:
- of transistors on a chip (of fixed size) doubles every 18 months
Virtual Machines - talk about virtualizing resources - (for example: Virtualbox). you are going to be running an operating system as a program.
50 million lines of code per user. Hypervisor - on top of that you are going to run your own instance of the operating system. Unix was designed as a multi user operating system. Designed to allow many people to share the same computer. But instead of doing that you run entire operating systems for one user. This is horribly wasteful. Also very useful.
Sequential reads are much faster than random reads.
Solid state disks - writes are very expensive, you can't write too many times to the same sector. It is dead.