Week 7: Muddy Virtual Memory

As I watched the lecture on “Operating System Functions” I was first a bit confused on how virtual memory and file swapping worked, but after watching Professor Olson explain it a few times I believe I have a decent understanding on the matter.

The use of virtual memory becomes necessary when the amount of memory in a computer is not sufficient to handle all tasks thrown at it by the operating system, system utilities, and application software. When this overload occurs the operating system will come in and create more room for data by creating this “virtual” memory. The OS creates virtual memory by “swapping” files among the computer’s RAM and storage. The computer’s RAM needs to contain all frequently and recently used data, and all data not being used frequently or recently will be swapped into storage. If data that is rarely used is in storage and needs to be used to perform a task then the OS will swap it into the RAM and bring some other data not frequently used into storage.

The use of virtual memory is beneficial in the fact that it allows a computer to exceed its maximum memory capacity, but it also will make a computer much slower. As Professor Olson stated the most efficient way to handle this problem would be to buy more RAM to install into your computer.

Week 5: Muddy Memory

In week five the greatest difficulty that I ran into was trying to differentiate among the different types of memory. This is my best understanding of computer memory. First of all, let me define computer memory on a broad spectrum: computer memory is usually a group of chips installed on a small circuit board that stores data to be used at a later point in time. Now that we know what computer memory is and what it does we can differentiate the many types of computer memory into two basic categories: volatile and non-volatile.

Volatile memory stores all of the frequently used data and instructions, but its content will be erased once the computer is turned off. The most basic form of volatile memory is called Random Access Memory (RAM). With time came innovation and the creation of many types of RAM: Static RAM, Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), DDR2 SDRAM, Dual Channel DDR2 SDRAM, DDR3 SDRAM, and RAMBUS. To my understanding the most widely used type of RAM is DDR3 SDRAM and DD2 SDRAM because they are affordable yet fast.

Non-volatile memory is much slower than volatile memory, but it does not lose its content when the computer is turned off. Types of non-volatile memory are Read Only Memory (ROM), and Flash Memory. Most types of ROM have data that is written into it at production and this data cannot be changed in any way. To my understanding EEPROM came along before the creation of Flash Memory and it was the first rewritable non-volatile memory.