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Memory Guide

HP Printer Memory | Lexmark Printer Memory | Glossary of Terms

FAQs

  1. What is RAM?
  2. What do I need RAM for?
  3. What's the difference between memory and storage?
  4. Can you tell by looking at a module if it is SDRAM, FPM, EDO etc?
  5. What is the difference between ECC and parity?
  6. What is a refresh rate and self refresh?
  7. What is EEPROM?
  8. What is the difference between CL2 and CL3?
  9. Can I use PC100 modules in PC66?
  10. What is the difference between Gold and Tin contacts?
  11. 60ns and 70ns, Which do I use?
  12. How do I protect my equipment from static electricity?

  1. RAM Random Access Memory Temporary storage area used to load program instructions and to store files currently in use. Random comes from the fact that the CPU can retrieve information from any single location, or address, within RAM.

  2. While a computer is running, it uses its memory to hold the operating system, the applications you're working in (word processing, database, illustration program, etc.) and the files or documents you're working on. If you don't have enough RAM to hold all of this information at once, many computers can be set up to use the hard drive to store the overflow. This is known as using virtual memory, the swap file, or the scratch disk. The data path from the computer's Central Processing Unit (CPU) to the hard drive is much slower than the data path to the RAM chips. Also the RAM chips move data around inside themselves much faster than hard drives can. As a result, a computer with less RAM may take significantly longer to perform tasks than a computer with an identical CPU and more RAM. Also, computers with insufficient RAM may have more memory errors, more general protection faults, more system crashes.

  3. Memory refers to the amount of RAM a computer has installed, and storage refers to the capacity of a computer's hard drive. Often they are both measured in megabytes (MB) to describe how much information each can contain. RAM is only active when the computer is operating properly. Information stored on the hard drive, on the other hand, remains intact whether the computer is running or not. This is why it is important to save your work often, so that if the computer crashes, or if power is interrupted and your computer suddenly shuts off, you only lose what you've done since you last saved.

  4. SDRAM, EDO and FPM chips look similar to each other. By looking at a memory module one cannot tell what it is. The best way to tell the difference is to reference the part number on the chip. Most DRAM manufacturers have reference books or lists on their WEB sites.

  5. Parity is a form of error detection, which can detect memory errors and halt the system to prevent data corruption. ECC memory is more complex form of error detection which not only detects, but also corrects most memory errors while your system is running.

  6. A memory module is made up of electrical cells. The refresh process recharges these cells, which are arranged on the chips in rows. The refresh rate refers to the number of rows that must be refreshed. The common refresh rates are 2K, 4K and 8K. The 2K components are capable of refreshing more cells at a time and they complete the process faster, therefore 2K components use more power that 4K or 8K refresh. The 4K components are capable of refreshing less cells at a slower time, but they use less power. Some specially design DRAMs feature self refresh technology, which enables the components to refresh on their own -- independent from the CPU or external refresh circuits. Self refresh, which is built into the DRAM itself, reduces power consumption, and it is commonly used in notebook computers

  7. An EPROM (Erasable Programmable Read Only Memory) is a chip that can be programmed with various types of information about the memory module. The CPU uses this information when booting up to understand what kind of memory is in the system and adjust its settings accordingly

  8. CL2 (Cas Latency 2) is a little bit faster than CL3 (Cas Latency 3) because during one step in the column accessing process you only have to wait two clock cycles instead of three clock cycles. The overall performance difference is minor, but some systems are designed to only support type of memory or the other.

  9. The PC 100 modules are backwards compatible, but if your computer won't benefit from using a PC 100, it is not recommended. If you are planning on upgrading your motherboard to one that supports PC100 modules and you know it will fit both motherboards, you can upgrade with it.

  10. The general overall rule is to match gold leads with gold contacts and tin leads with tin contacts. When you mix the two metals you speed up the natural process of corrosion. During this corrosion process a small electrical current can be formed (much in the way of how batteries work. Batteries contain an acid that is in a chamber with metal discs, the acid excels the corrosion process to create an electrical current.) and can cause problems with the way your RAM functions. When upgrading, confirm what type of connectors and leads you have, then order the same. This rule will not always work since it may not be possible to get the correct match of gold leads with gold contacts and tin leads with tin contacts. (Check for availability) Problems are rare but can happen. To prepare yourself and to help keep your computer at its best level of performance, here are a few guidelines to help you. When you first upgrade the memory, ground yourself, then as you are installing the module, do not touch the surface of the connecting pins. Any moisture or oils that can come from your fingers can speed the corrosion process. Try to have your computer in a low humidity area with a normal, stable temperature. This will help more than just your memory. 

  11. Building on the knowledge that 60ns (nano seconds) is faster than 70ns, you cannot put modules rated at slower speeds in a computer that requires the faster speed. You can, however, place faster modules in a slower system, but this will not enhance your performance. The faster modules have the capability of performing at the lower speed and fulfilling the necessary speed specification. Complete banks must have the same speed. You can't mix speeds within a bank.

  12. First, unplug the computer then ground yourself by either purchasing an anti-static bracelet or you can touch the power supply box. If you work a lot with computers, anti-static mats are available as well.