Memory 101

[Lyte]

Memory 101

Glossary

Cache - Pronounced as “cash”… like money. Cache is a high-speed access area that can be either a reserved section of main memory or a storage device.

Conventional Memory - Portion of PC computer memory that totals 640kb unless the computer has less than 640kb of memory. This portion of the RAM is the only portion of memory DOS is able to access unless a memory manager is being utilized.

DDR - Short for Double Data Rate, DDR is a type of memory that utilizes both the rising and falling edge of the system clock which could potentially double the speed of the memory.

DRAM - Short for Dynamic Random Access Memory, DRAM is one of the most commonly found memory modules in PC compatible personal computers and workstations. DRAM stores its information in a cell containing a capacitor and transistor; because of this design, these cells must be refreshed with new electricity every few milliseconds allowing the memory to keep its charge and hold the data as long as needed. When using this type of memory, if the computer is powered off, the information within memory will be lost.

Flash memory - A type of computer memory developed by Intel Corp. Flash memory is non-volatile memory that is an integrated circuit that does not need continuous power to retain the data. It is much more expensive than magnetic storage and is therefore not practical as a replacement for current hard disks or diskettes.
The computer's BIOS is considered a type of flash memory; flash memory is also often used in digital cameras.

Local memory - When referring to a computer with more than one computer processor, local memory refers to a portion of memory that is designated to a specific computer processor that no other processor is capable of accessing. Local memory is also used to describe a portion of memory that a software program or utility only has access to once obtained.

MDRAM - Short for Multibank DRAM, MDRAM was developed by MoSys and is a type of video graphics memory.

Memory - More commonly known as RAM, memory is a location where information is stored that is currently being tilized by the operating system, software program, hardware device, and/or the user.

There are two types of memory, volatile memory and non-volatile memory. Volatile memory is memory that loses its contents when the computer or hardware device loses power. Computer RAM is a good example of a volatile memory. Non-volatile memory, sometimes abbreviated as NVRAM, is memory that keeps its contents even if the power is lost. CMOS is a good example of a non-volatile memory.

PRAM - Short for Parameter RAM, PRAM is a small, battery-powered section in Apple Macintosh computers used to store basic settings such as the time and the data. PRAM is similar to IBM compatible computers' CMOS.

RAM - Short for Random Access Memory, RAM, also known as main memory or system memory, is a term commonly used to describe the memory within a computer. Unlike ROM, RAM requires power; if power is lost, all data is also lost. Below is an example image of a 512MB DIMM memory stick.

RDRAM - Short for Rambus Dynamic Random Access Memory, RDRAM was developed by Rambus and is a technology of memory that offers a 1.6 GB/s of theoretical memory bandwidth, and offers improved memory access at a slightly higher cost when compared to SDRAM.

ROM - Short for Read-Only Memory, ROM is a type of memory that is capable of holding data and being read from; however, it is not capable of being written to or having its data modified. Unlike RAM, ROM is capable of keeping its contents regardless if it has power or not.

SDRAM - Short for Synchronous DRAM, SDRAM is a type of DIMM memory that synchronizes itself with the computer's system clock to provide synchronization between the memory and the computer processor.

SRAM - Short for Static RAM, SRAM is a type of computer memory that requires a constant power flow in order to hold information. Although quicker than DRAM, SRAM is much more expensive and requires more power; therefore, it is commonly only used in cache and video card memory.

Volatile memory – Volatile memory is one whose content is erased when the system's power is turned off or interrupted in some way. RAM is volatile, but ROM is not. It is because of RAM's volatile nature that users must frequently save their work to a permanent medium such as a hard drive to avoid losing data if the system's power is interrupted.

Non-volatile memory - More commonly known as RAM, memory is a location where information is stored that is currently being utilized by the operating system, software program, hardware device, and/or the user.

Virtual memory - Virtual memory is a method of using the computer hard disk drive to provide extra memory for the computer. Segments of memory are stored on the hard disk drive known as pages. When a segment of memory is requested that is not in memory it is moved from the virtual memory to an actual memory address.

What is Memory?

“Memory” (from here on we’ll call memory RAM - Random Access Memory) refers to the small rectangular modules, circuit boards, or memory sticks that are installed in sockets on a computer's motherboard. There are different types of memory, including FPM DRAM, EDO DRAM, SDRAM, and RDRAM, each of which has its own distinctions and advantages. Most computers only support one type of memory, but some also support two types.

Your computer uses RAM so that the CPU (central processing unit) doesn’t have to constantly retrieve data directly from the hard drive. The CPU cannot work efficiently if it has to repeatedly stop and search for the data it needs. RAM is used to store data temporarily, and the CPU can store and retrieve data from RAM more quickly and efficiently then if it were to search for it on the hard drive.

When you open a piece of software such as Word, Excel or Internet Explorer, data associated with these pieces of software is temporarily stored in memory. Again, the purpose of this temporary storage of data is to enable you to work quickly because your software is working quickly. More RAM allows your computer to store more data and retrieve it more quickly than with less RAM. Also, with enough RAM you can operate more applications simultaneously on your computer without consuming all its vital resources. Generally speaking… there are exceptions… the more RAM your computer has the faster and more efficient your data storage and retrieval will be.

What to Look For When Buying Memory

Adding more memory to your computer produces an overall improvement in its performance. Additional RAM allows your computer to run more programs simultaneously. This means you could surf the Internet, listen to music or play a game without your system slowing down. More memory also helps your computer to run complex software even faster, such as recent 3D games or voice recognition programs.

Although most ready-made computer systems come with RAM already installed, there may come a time when you have to buy more memory for your computer. There are certain questions that you have to ask and certain things that you need to look for in order to get the right type of RAM.

Shopping for memory is a matter of finding RAM that is compatible with your system in addition to comparing the performance and features. Different brands of computers or motherboards need different types of RAM. In the case of memory, one sides does NOT fit all. If you are looking to upgrade the RAM in your computer, then the first thing you need to do is find out what type of RAM you need to buy. Also, you need to find out how much memory your computer system can handle. You should be able find this information in your computer's user manual, the manufacturer or by providing your computer store with information regarding your other hardware (e.g. motherboard). It is important to remember that if you buy the wrong memory for your computer, it may not work or it may work but very poorly. Follow the manufacturer’s guide for your computer and motherboard before making your purchase.

When you are sure that you know what type of memory that you need to buy, the second thing that you need to decide is how much memory you want, and in what form you will buy this memory. RAM is measured either in megabytes or gigabytes. Most of today's computers use anywhere from 128 megabytes of RAM up to 1 gigabyte of RAM or more. Although some older model computers use less RAM, these days 128 megabytes is usually the least amount that you can get away with, and more often than not, it is not enough. It is best to have 256 megabytes of RAM or higher.

If you do not intend to replace your entire RAM, you'll need to determine how much memory your computer already has so that you do not purchase more than your system/motherboard can accommodate. You can do this by clicking on the “My Computer” icon on your desktop, or clicking on the Start menu and accessing “My Computer” from there. When the My Computer screen comes up, right-click on the middle of that screen, and then click on “Properties”. A window will pop up that lists the properties of your computer, and the amount of your computer's memory will be one of the things listed. It will say something like “256 MB of RAM”, or whatever amount your RAM is. Once you know how much memory your computer has, you can then decide on how much more you need.

How much memory you need for your computer system depends on several factors. First, what do you mostly use your computer system for, or what do you plan on using your computer system for in the near future? Large files obviously need a lot of room if they are to be stored and retrieved quickly and efficiently, and there are many programs that use much larger files than other programs. If you will be running a lot of video on your computer system, such as playing a lot of computer video games or transferring home videos to your computer, you will need the maximum amount of memory that your computer system can handle. Although graphics cards come with some of their own memory, your computer system will still need a lot of RAM to handle large amounts of graphics and videos. What type of operating system you are running will also determine the amount of memory that your computer system needs. Older operating systems like Windows 95 or Windows 98 need less RAM to run functions efficiently, and older systems usually cannot handle more than 256 megabytes of RAM. Newer operating systems such as Windows 2000 and Windows XP need more RAM to run their functions efficiently, and although they can run on as low as 64 Megabytes of RAM, they will run better on 512 megabytes of RAM or higher. Large intricate programs such as office suites that include word processors, spreadsheet programs, database programs and website building programs will take up a lot of memory on your computer, and will need a sufficient amount of RAM so that running them will not slow down your system. Although it is possible to install too much memory in your computer, this can usually be avoided by following your computer manufacturer's guidelines on the maximum memory that your system can handle. It is much more likely to run into problems by not having enough memory installed in your computer system. Typically people install the maximum memory their system allows. This will ensure the computer system will work just fine until it is replaced with a new system.

One Stick or Two?

The motherboard inside your computer has slots where memory sticks are inserted. If you will be adding the memory yourself, you need to know how many memory sticks are in your computer already, how much RAM is on each memory stick that is already in there, and how many memory stick slots are empty. Different types of motherboards will have different types and numbers of memory slots. If, for example, you have 4 memory stick slots on your motherboard, and there are two 64 megabyte memory sticks taking up two of the slots, then you can either put one 128 megabyte memory stick into one of the empty slots to double the amount of memory you have, or you can put one 64 megabyte memory stick into each of the other two empty slots for the same result. This will leave you with a total of 256 megabytes of RAM. However, if you wanted to upgrade to 512 megabytes of RAM, you would need to remove the two 64 megabyte memory sticks and either replace them by putting one 512 megabyte memory stick into one of the slots, two 256 megabyte memory sticks into two of the slots, or four 128 megabyte memory sticks into all four slots. Most people prefer to use the memory sticks with the higher megabytes of memory so there will still be empty slots for future upgrades.

Can I Mix Different Speeds or Brands of Memory Sticks?

While it is generally "okay" to mix different brands of memory sticks, for maxium performance you'll want to use sticks with the same same speed rating or clock rating. The speed rating of a memory stick determines how fast a computer system is able to write to and read data from a memory stick. Also, your computer system will write and read data only as fast as the lowest memory stick installed. Worse yet, using sticks of different speed rating can lead to conflict errors!

It is important to remember that memory plays a crucial part when it comes to how well your computer system functions. With all of the types of memory sticks, as well as the sizes and different brands, it can sometimes be difficult to decide which memory is best for your computer system, and this is where the experts come in. If you’re unsure about what type of memory to buy, you can take one of your memory sticks out of your computer and bring it with you to the store. As long as your computer is turned off when you remove the memory stick, and stays off until you put that or another memory stick back in it, it will not hurt your computer. When you remove the memory stick, be sure that you are grounded, and then transport the memory stick in a special static-free bag so that the stick won't be damaged by static electricity. Show your memory stick to a knowledgeable person at the store, and he or she should be able to help you decide how much memory to buy, and what type you will need.

Every time you consider buying a new computer system you should check to see if it has enough RAM to meet your needs. If you are interested in a certain ready-made system but need more memory, most manufacturers or retail stores will be glad to upgrade the memory, for a price.


How do I install Memory Sticks?

There are a few points to be clear about before beginning:

· Be certain opening your computer will NOT void your computer’s warranty. Carefully review your computer's documentation for instructions.
· Read all installation instructions that came with the memory sticks or the manual for your computer.
· Before handling the sticks, touch a grounded piece of metal to discharge static electricity from your hands. Static can damage sensitive computer components.
· Turn off your computer and unplug it from its power source.

Open the computer case to access the internal components; this may require unscrewing several screws that hold the cover in place.

Locate the memory slots on the motherboard, noting the numbering of each bank of slots. Memory banks are usually numbered starting with zero, then one, two and so on. You should always install new memory in the lowest-numbered bank available, first. Meaning, if numbers one and two are taken, add your next stick to slot number three. If you are unable to determine clearly the order in which the memory slots are numbered, then you can use a trial and error method. Some computers may not recognize memory installed in the wrong slot. If your computer fails to recognize the new memory or if you notice erratic computer behavior, repeat the installation procedure and move the memory into a different slot.

When you have located the correct slots insert the memory module as shown in the instructions. Different types and sizes of memory modules are often inserted in slightly different ways. There is no standard method but be sure never to force a stick into place. If the slot doesn’t receive the stick easily try rocking it gently into the socket one corner at a time. Again, do NOT force it! Lock the module into the socket as shown in your instructions. Repeat this procedure for any additional memory sticks you may have.

Replace the cover to your computer case, plug in your computer, and then turn it on. Most systems do a memory assessment (count) upon boot up. It is at this point your computer should recognize the added memory. If the computer refuses to boot, there might be a memory error or an incorrectly installed memory module. Start again and double check all the installation steps. If the problem persists, try removing the new memory to see whether the error disappears. If so, you can add one stick at a time to see if the error returns because of one specific (faulty) stick. If you have followed the installation procedure correctly and you continue to get an error upon start-up, you may need to ask for technical support from the memory's manufacturer or from a trained technician.

If there are no problems and the computer starts up normally, then you’re all done! The computer will use the new memory automatically. There is no additional step or configuration of software required.