why cache memory is needed? give any two reasons.?
368341
CPU caches\n\nSmall memories on or close to the CPU chip can be made faster than the much larger main memory. Most CPUs since the 1980s have used one or more caches, and modern general-purpose CPUs inside personal computers may have as many as half a dozen, each specialized to a different part of the problem of executing programs.\n\nDisk buffer\n(also known as disk cache or cache buffer)\n\nHard disks have historically often been packaged with embedded computers used for control and interface protocols. Since the late 1980s, nearly all disks sold have these embedded computers and either an ATA, SCSI, or Fibre Channel interface. The embedded computer usually has some small amount of memory which it uses to store the bits going to and coming from the disk platter.\n\nThe disk buffer is physically distinct from and is used differently than the page cache typically kept by the operating system in the computer's main memory. The disk buffer is controlled by the embedded computer in the disk drive, and the page cache is controlled by the computer to which that disk is attached. The disk buffer is usually quite small, 2 to 16 MB, and the page cache is generally all unused physical memory, which in a 2006 PC may be as much as 2GB. And while data in the page cache is reused multiple times, the data in the disk buffer is typically never reused. In this sense, the phrases disk cache and cache buffer are misnomers, and the embedded computer's memory is more appropriately called the disk buffer.\n\nThe disk buffer has multiple uses:\n\nReadahead / readbehind: When executing a read from the disk, the disk arm moves the read/write head to (or near) the correct track, and after some settling time the read head begins to pick up bits. Usually, the first sectors to be read are not the ones that have been requested by the operating system. The disk's embedded computer typically saves these unrequested sectors in the disk buffer, in case the operating system requests them later. \nSpeed matching: The speed of the disk's I/O interface to the computer almost never matches the speed at which the bits are transferred to and from the hard disk platter. The disk buffer is used so that both the I/O interface and the disk read/write head can operate at full speed. \nWrite acceleration: The disk's embedded microcontroller may signal the main computer that a disk write is complete immediately after receiving the write data, before the data are actually written to the platter. This early signal allows the main computer to continue working even though the data has not actually been written yet. This can be somewhat dangerous, because if power is lost before the data are permanently fixed in the magnetic media, the data will be lost from the disk buffer, and the filesystem on the disk may be left in an inconsistent state. On some disks, this vulnerable period between signaling the write complete and fixing the data can be arbitrarily long, as the write can be deferred indefinitely by newly arriving requests. For this reason, the use of write acceleration can be controversial. Consistency can be maintained, however, by using a battery-backed memory system in the disk controller for caching data - although this is typically only found in high end RAID controllers. Alternately, the caching can simply be turned off when the integrity of data is deemed more important than write performance. \nCommand queuing: Newer SATA and most SCSI disks can accept multiple commands while any one command is in operation. These commands are stored by the disk's embedded computer until they are completed. Should a read reference the data at the destination of a queued write, the write's data will be returned. Command queuing is different from write acceleration in that the main computer's operating system is notified when data are actually written onto the magnetic media. The OS can use this information to keep the filesystem consistent through res
1845
Since the main memory (RAM) is expensive, it usually has lesser capacity than the hard drive.  However, the problem with that is the RAM gets filled quickly with all your running programs.  However, the CPU (processor) multi-tasks, hence it doesnt need the programs (data and instruction words in the RAM) all the time.  Thats where the virtual memory comes into picture.  Virtual memory is basically part of the drive which is used as a temporary "parking space" for data and instruction words which can't be held in the RAM.  When programs are no longer requred they are "swapped" to the hard drive from the RAM and shuttled back to the RAM when the CPU gets ready to process them (depending upon the scheduling algorithm).\n\nYou are getting the error because you have assigned less virtual memory (or the system has assigned less vitual memory).  Hence, when the RAM gets full, its doesn't get any "parking space" on the hard drive and you get the error.\n\nIn order to bump up the virtual memory and improve system performance, view the following page.  It is really helpful!
993323
well...let's have a look on how this works:\n(very simplified)\nvirtual memory is a means of page switching, it switches a memory page with a page of the same size on the harddrive,thus the aparent memory is 2 times the size of the memory page.if the system needs data from the page on the harddrive ,the page will be switched back.\n\nActually there are many pages used, of small sizes.on the harddrive there are stored in one single file,being delimitated by their size only.\nso...now imagine you have 1Gb of ram, and your computer is only used for basic things.....wouldn't be a waste of space to have a 10Gb virtual memory?\nand another thing...seeking in a small file is faster than in an extremely large file,so.....use a fair amount of space for virtual memory....not the max available as it it's pointless.\nhope this helps
76002
If you have the Windows XP firewall, then you've already gotten the answer.  But in my opinion, if you have a hardware router, get rid of the software firewall.  If you don't open any ports you're better protected than with a software firewall and no memory is used.  Why waste ram if you don't need to.\n\nDon't listen to the other opinions.  Computers are my job.  IF (and only IF) you have a router, get rid of the firewall.
445595
Pronounced cash, a special high-speed storage mechanism. It can be either a reserved section of main memory or an independent high-speed storage device. Two types of caching are commonly used in personal computers: memory caching and disk caching. \nA memory cache, sometimes called a cache store or RAM cache, is a portion of memory made of high-speed static RAM (SRAM) instead of the slower and cheaper dynamic RAM (DRAM) used for main memory. Memory caching is effective because most programs access the same data or instructions over and over. By keeping as much of this information as possible in SRAM, the computer avoids accessing the slower DRAM. \n\nSome memory caches are built into the architecture of microprocessors. The Intel 80486 microprocessor, for example, contains an 8K memory cache, and the Pentium has a 16K cache. Such internal caches are often called Level 1 (L1) caches. Most modern PCs also come with external cache memory, called Level 2 (L2) caches. These caches sit between the CPU and the DRAM. Like L1 caches, L2 caches are composed of SRAM but they are much larger. \n\nDisk caching works under the same principle as memory caching, but instead of using high-speed SRAM, a disk cache uses conventional main memory. The most recently accessed data from the disk (as well as adjacent sectors) is stored in a memory buffer. When a program needs to access data from the disk, it first checks the disk cache to see if the data is there. Disk caching can dramatically improve the performance of applications, because accessing a byte of data in RAM can be thousands of times faster than accessing a byte on a hard disk. \n\nWhen data is found in the cache, it is called a cache hit, and the effectiveness of a cache is judged by its hit rate. Many cache systems use a technique known as smart caching, in which the system can recognize certain types of frequently used data. The strategies for determining which information should be kept in the cache constitute some of the more interesting problems in computer science.
256882
In General ALL THESE ARE MEMORY.\nIf we consider the time taken to access data in the memory;\nCACHE < RAM < HARD DISK\n\nIf we consider cost in relation to capacity;\nCACHE > RAM > HARD DISK\n\nHowever, you cant upgrade Cache simply but others u can
485162
Ummm, A COMPLETELY empty memory?!... Well, there's no completely memory I think! Memory we allocate, is always full of garbage. BUT, if u use assembly, u can 1st give the value of 0 to the bits of that part of memory u wanna allocate, and then try to do what u want!...
794134
Increasing memory is always good. If you are running XP I would suggest a minimum of at least 512 mb. If you can afford the 1GB go for it.
150264
They are completely different things\nA processor CONTAINS L1 and L2 Cache. L1 and L2 are onboard memory chips which usually speed up the CPU.\nprocessor=empty brain\nL1,L2,L3 Caches=brain cells
954026
origamimark is completely correct. The benefits are small and will cause your CPU to fail much sooner. I would look into other methods before risking burning your CPU. Like he said, more memory, faster hard drives, etc.
548122
Why the memory problem in Windows 95, 98 and Me isn't fixable:\nhttp://aroundcny.com/Technofile/texts/tec041501.html\n\n\nWindows ME Problems:\nhttp://bermangraphics.com/problems/winme.htm
1030086
Depends on what OS your running and what applications you run, but as a general rule, performance improved if you increase to 512 mb.\n\nI found it worth the extra cost to go to 1GB of RAM especially if you want to do any image processing (Photoshop or GIMP) or run any application which process large chunks of data.
299804
Memory is HARDWARE, not software.  \n\nAll you have to do is buy the right kind of memory and stick it in.   A caveman could do it. \n\n(no offense)
374394
It wont make things load slow, they arent stored in memory, they are cached on disk. But you can also use them to track where you have been going and what you have been doing too. If you dont have the size maxed out, you can eat a lot of hard drive space too.
92095
I think due to in-sufficient Memory Room i.e. RAM [Random Access Memory] your should add sufficient Memory Bank in your PC.
143421
if you want disk space, you need a larger hard drive... memory is not space.
864250
If you're not running at least 2 GB of RAM I would not suggest that you do this!  But here's how you accomplish what you've asked for.click start, then control panel.  Then performance and maintenance, then system.  On the tabs that open up click advanced.  In the box marked performance click settings.  In the new window that opens click advanced.  At the bottom of this page you will see memory settings, on the next page that opens click no cached memory.  Click OK and apply your done