This is a simplified illustration of Memory Management

Date: 2015-10-07; view: 442.

How Computer Memory Works? How is memory organized in a computer?

LESSON PLAN

1. How computer Memory Works

2. Using the Application Programming Interface (API)

3. The GlobalMemoryStatus function

4. Getting information about memory

1) Hello. Today we have a laboratory work number 7.

2) Let's get started.

3) The subject of the laboratory work is “Getting memory status based on Application Programming Interface (API)”

4) Memory is an important resource that must be carefully managed. Most computers have memory hierarchy and the job of operating system to coordinate how these levels of memory are used. The part of operating system that manages the memory hierarchy is called the memory manager. Its job is to keep track of which parts of memory are in use and which parts are not in use, to allocate memory process when they need it and deallocate it when they are done, and to manage swapping between main memory and disk when main memory is too small to hold all the processes. I'd like to draw your attention to the following...

Fast, powerful CPUs need quick and easy access to large amounts of data in order to maximize their performance. If the CPU cannot get to the data it needs, it literally stops and waits for it. Modern CPUs running at speeds of about 1 gigahertz can consume massive amounts of data -- potentially billions of bytes per second. The problem that computer designers face is that memory that can keep up with a 1-gigahertz CPU is extremely expensive -- much more expensive than anyone can afford in large quantities. Computer designers have solved the cost problem by "tiering" memory -- using expensive memory in small quantities.

The cheapest form of read/write memory in wide use today is the hard disk???. You can buy hard disk space for penny per megabyte, but it can take a good bit of time to read a megabyte off a hard disk. Because storage space on a hard disk is so cheap and plentiful, it forms the final stage of a CPUs memory hierarchy, called virtual memory???.

The next level of the hierarchy is RAM???. The bit size of a CPU tells you how many bytes of information it can access from RAM at the same time. For example, a 16-bit CPU can process 2 bytes at a time (1 byte = 8 bits, so 16 bits = 2 bytes), and a 64-bit CPU can process 8 bytes at a time.

A computer's system RAM alone is not fast enough to match the speed of the CPU. That is why you need a cache??? (discussed later). However, the faster RAM is, the better. Most chips today operate with a cycle rate of 50 to 70 nanoseconds. The read/write speed is typically a function of the type of RAM used, such as DRAM, SDRAM, RAMBUS.