 | Randy Johnston
has been involved in computing for over 25 years. In addition to being a top-rated and entertaining speaker presenting technology seminars worldwide for K2 Enterprises (www.k2e.com), he is also Executive Vice-President and Co-owner of Network Management Group, Inc., a full-service computer networking and service company. Randy recently published Technology Best Practices for Wiley Publishing. You may contact Randy by e-mail at randyj@nmgi.com, or by phone at (620) 664-6000. |
Computers & Software
2002-04-01 14:47:00
What exactly is RAM?
Question: What exactly is RAM? Does it relate to the resources available and/or used at any given time on my computer? With all of the advancement in technology over the last several years, why hasn't anyone figured out how to solve programs using up too many of the available resources?
Answer: RAM (Random Access Memory), sometimes referred to as main memory or volatile memory is where all data and programs reside in computers. Current computer designs currently have four main components. If you think of a computer as having a Central Processing Unit (CPU), memory, input and output, you can see with RAM we are focusing on one of the four main components of all computers. Since all programs and data must reside in RAM to be processed, RAM is definitely one of the constraining factors of computers.RAM is measured in bytes, the equivalent of a single character, and then for convenience, larger amounts of RAM are spoken about in metric terms or units of measure. 1,024 bytes = 1K (sometimes people mistakenly think that 1K means just 1,000), and 1,024K = 1 Megabyte (MB). We buy RAM in increments of 8, 16, 32, 64, 128, 256, and 512 MB. RAM costs vary widely as a commodity, but 64MB of RAM is currently $30-50.When an operating system is loaded in RAM, it takes some portion of the RAM available to provide all of the interfaces between application programs and the hardware itself. We then can load one or more application programs to perform specific tasks. At this point, we may have taken a relatively small portion of the RAM available, or almost all of it, depending on the operating system and the applications and the amount of RAM physically installed in the machine. In the Microsoft Windows environment, for the operating system plus two applications, you might use 32-80MB of RAM. Every time we start more applications, or every time we start and stop an application, we aggravate the memory loss or usage problem.The data that is going to be used must fit in the remaining RAM in your computer, but because data often takes a large amount of space in RAM, it is rare that all your data can fit in RAM at one time. Therefore, programs read in data in a few records at a time from your hard drive or disk, update them, and put the records back. In the case of word processing, the entire document is often in RAM, but occasionally becomes so big, portions of the document must be read from disk reducing performance. RAM is at least 100 times faster than disk. Disk has the advantage of remembering the value when power is turned off. RAM loses all values when power is lost.The way your operating system uses (or loses) resources will be determined by the operating system. When portions of RAM are no longer in use, one job of the operating system is to gather up the unused portions of memory, and reuse them. If the routine to gather up the now unused memory (called garbage collection) is not efficient, you can run out of resources. In the Microsoft Windows environment, you can see the effects of these processes in the percent resources free (viewed by right mouse clicking on My Computer and selecting properties). The operating system, support programs and application programs all consume these resources. When the percentage of resources free drops below 70%, most Windows operating systems become less stable.Different operating systems do a better job of garbage collection or clean up the unused resources in a better way. Desktop operating systems like Red Hat Linux tend to have far less problems with improper garbage collection. Microsoft Windows operating systems are some of the worst at losing memory, and locking up from a lack of resources. People in the minicomputer and mainframe world have been aware of the performance loss when memory is not recovered. They have accommodated this by restarting or IPLing (Initial Program Load) their machines in the middle of the night. This results in a far more stable system, and performance gains. It is clear that some of the Linux/UNIX operating systems or midrange operating systems like OS/400 are very stable and don't lose much memory that they can't recover. As consumers, though, we tolerate this reduction in performance without much complaint, and simply restart our machines when they lock up or restart them on a regular basis (daily, weekly, whatever). Most of us are reluctant to give up our Microsoft operating systems and application compatibility on the desktop just to gain more stability.
