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Perl CGl Programming: No experience required.
Installing the Right Amount of MemoryDeciding how much memory is adequate for your Web sites computer is pretty simple: The more the merrier. The more RAM (random access memory) you can throw at UNIX, NT, or Windows 95, the happier theyand youwill be. The memory is where much of what your computer does takes place. A program has to be loaded from disk into memory before it can run; its individual instructions and data are fetched one by one and executed by the processor. Thus, if you have a lot of memory installed, more can be queued up for the processor to do at a time and less has to be read from the disk. It is axiomatic that the slowest component of your system is your disk drive. You want to spend as little time rummaging through it as possible. The three operating systems weve been discussing extend the computers abilities with a trick called virtual memory, in which the disk is treated as an extension of memory. If a program requires more memory than is actually available on the machine, its code can be paged out to the area of the disk that is set aside for virtual memory. Virtual memory effectively sets the amount of memory a program can use to the size of the disk if youve made that much of it available (not a wise policy, by the way). However, every time the operating system pages code out to and back from the virtual memory on disk, it is calling on that slowest component of your system to do some work. Virtual memory allows you to run anything regardless of its memory requirements, but you pay a heavy toll in performance if you have so little memory that most of it winds up being virtual. If you play with a computer with a relatively small amount of memory installedsay, less than 16MBwith Windows 95 or NT, and you crank up a bunch of programs that tend to hog memory (Microsoft Word in any of its versions is a good example), you will notice that things slow to a crawl from time to time, the mouse cursor may even hang or act jerky, and you can hear the disk being absolutely hammered. All of your programs will continue to run, but at interminably slow speeds. This phenomenon occurs when your operating system is taking advantage of its virtual memory. The OS is paging code out to the disk, and then reading it back. That slowest component of the system is hanging things up. Obviously, the best way to eliminate the problem is to add more memory. Besides, its ridiculously cheap these days, at least compared with what RAM sold for a few years ago, so there are no excuses for not packing your machine with as much memory as it will hold. Because of the memory demands of all three of our operating systems, and the way virtual memory works, you can often bring a moderately slow computer up to acceptable speeds just by loading it up with more memory. It can be cheaper than a processor or motherboard upgrade.
An adequate basepoint is 16MB of memory, but if you can afford it, you really should go a lot further for your Web site. A heavily used UNIX system will be happiest with 64MB or more; NT Server, which due to Microsofts licensing restrictions is what youll need to run a Web server, doesnt function well with less than 32MB; and Windows 95 is a real dog with less than 16MB.
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