Operating Systems

[GermaineMartin]

Operating Systems

            The operating systems of our era have to have first a strong CPU to do all the computations and operations for the computer to help the operations run. If you don’t have a brain you do not have anything. A computer must have a CPU or brain. There are two basic functions of operating systems. Number 1, to keep the computer from errors or exceptions. Number 2, to run the computer. The operating system must have a cache for extra memory. It must have registers to do the basic functions and for short-term memory.

There have to be processes. A process is the task of a computer. It’s what the computer does, for example: if I’m going to put A + B = variable C, that is a task. To do the algorithm the computer needs to get the variable A from its register, get B from its register and use the operation of addition and put it in the variable C, which has its own register.

            Processes are how the task is done. There has to be a new process to start at the beginning. Then you have to have a wait process where the computer is waiting for that process to be done. Then you have to have a write process so the computer can write it to memory. Once the computer writes it to memory, you can terminate the process.

            Main memory is basically the memory that runs the computer. Part of it is the cache. There are three levels of cache and you’ve got registers and the CPU. That’s pretty much the physical addresses of where things are in the real world. Those are the physical addresses. Then, on the other hand, we have virtual memory, which is the memory that programmers use to program the computer. That is a virtual memory, like an assistant to the programmer. Programmers always want lots of memory. Virtual memory is giving programmers extra memory to write programs. They use certain methods: first-in-first-out page replacement, there’s the LRU page replacement and the approximate page replacement, which is a little better than the first-in-first-out page replacement. There’s optimal page replacement which is too hard to implement. There’s second chance page replacement.

[main memory and virtual memory picture]

            Files are collections of data on certain subjects, like this paper is going to be a file. We also have mass storage, which helps us with the memory. And then we have the I/O devices like the keyboard, the microphone, the camera, and the game controllers if you play a game.  Those support hardware for the computer, including the monitor which every computer must have.

[   I/O and files]

To protect the computer, we have to have protection from hackers, people who want to hack into your computer. They are called crackers. It is hilariously funny, but that is the technical term for a hacker, a cracker. In order to run the computer we have what we call capabilities at the control list. Capabilities go with the different files or objects. It acts as control that has to do with the domain of the computer, or the protection fence of the computer.

From the access control list we come up with a matrix which helps in controlling access to your computer. It keeps unauthorized people from coming into your computer and deleting files or stealing your personal information or taking your picture to make fake I.D.s. The idea is to keep people from getting into your computer and give you program errors while you are writing a paper or writing a program. You’re trying to keep people from doing those malicious acts because it will be you that gets in trouble, not the hackers (or the crackers).

I will use the algorithm part of the next class, because the next class is about algorithm and I will learn more about matrices and this. I would imagine I am going to learn a lot of things that will help me progress and get jobs.