Q: When I upgraded my PC from 8MB to 20MB of RAM, the boost in Windows  95's performance was dramatic. Then I bumped up my RAM to 32MB and  everything started running slower. Why?

 A: The more system RAM, the larger the virtual memory swapfile Windows 95 creates on your system. (A swapfile is a chunk of hard disk space Windows uses  like RAM when memory is low.) The larger the swapfile, the more Windows 95 uses it. It stores data there instead of using available RAM. As it grows, the swapfile can also become defragmented, which also slows performance.

The remedy is to tell Windows 95 to limit its dependency on the swapfile. Select Start*Settings*Control Panel, click the System button, hit the Performance tab, then press the File System button. Select Hard Disk and change the Typical role of this machine entry to Network server. Click the Apply button, then hit OK. In the Performance tab, click the Virtual Memory button and check the Let me specify my own virtual memory settings box. Then set the minimum to half the installed RAM and the maximum to equal the installed RAM.

You should also run your PC's setup and check the wait-state setting. Raise or lower the value by one unit and see what happens to performance. Some-times 1 or 2 wait-states is better than none for your system's memory. Timing differences between dissimilar chips in your system may also bog things down.

Or, you may have a RAM error that only appears as slow performance under Windows 95. A memory diagnostic like DiagSoft's QAPlus/fe or Norton Diagnostics can reveal the problem.
 

Reader feedback indicates that some or all of the suggestions I made for regaining lost performance after adding RAM to a system have not helped as anticipated. The suggestions I gave are just that: suggestions. As with almost anything you can do to or with Windows 95, settings for memory, swap files, 32-bit access, and cache are all highly dependent upon various system configurations, from chipsets to  BIOS/setup parameters to disk adapters to drivers to the drives themselves. If your  system performs better with a larger swap file vs. using the additional RAM, that's  the solution for you. If your system requires or works best with a specific device driver loaded in CONFIG.SYS rather than the native Windows 95 driver, that's the solution for you. There are three other considerations. You may have an incorrect         Wait State setting in the BIOS/CMOS setup which you may or may not be able to access and change via the setup program at boot time. Also, the order in which  certain RAM modules are installed in the sockets may affect how the system handles the additional RAM. Some system boards are just poorly designed and can't run or address memory as fast as they should. Check your system manual to see if your memory can be rearranged. Finally, running a memory diagnostic test may reveal a subtle data error, caused by timing or a RAM module incompatibility with your                 system board.
 
Low memory
Q: I just upgraded my PC from 8MB to 16MB, but Windows 95 still won't let me open more than two applications at a time. It keeps complaining that memory is low.  How can that be?

A: Keep in mind that memory is many things to Windows. It not only uses the RAM chips in your system, it also takes a slice of hard disk (called a swapfile or virtual memory) and uses it when RAM runs low. I suspect you're loading big programs and/or files, and you're low on available disk space; you probably have less than 10MB. Windows 95 gets cranky because there isn't enough room to swap files, deal with the temporary files your word processor and Web browser lay down, and so on.

The first thing to do is clear out some disk space. First delete any unneeded temporary files. That means purging your Web browser's cache; dumping temporary  files in folders like \TEMP, \TMP, \WINDOWS\TEMP, and similar hiding places; and axing files that end with .TMP or begin with a tilde (~). Uninstall unused programs and delete subsidiary files like README.TXT that you've read and don't  need. Check your email program's Trash directory as well. It probably needs emptying.

Next, dig into your email program delete or archive old messages. In fact, archive  anything on your system—programs, data, whatever—with a compression program like WinZip. Note: Existing ZIP and self-extracting EXE setup files may get bigger if  you try to compress them. But just about everything else will shrink nicely.

Finally, get a bigger hard drive and better yet, more RAM. In spite of what  Microsoft says, Windows 95 is really a 32MB operating system.

Squeeze Your Swapfile
Swapping drivers and applications between virtual memory and your hard disk can chew up a lot of cycles. Set the size of your swapfile intelligently-to 2.5 times RAM-and you'll increase performance. Go to Control panel/System/Performance and click on the Virtual Memory button. Select the option "Let me specify my own virtual memory settings." Select the disk partition on which to place virtual memory (defragment it first for best results),  then type in the same value for Minimum and Maximum (this reduces the time Windows 95 spends resizing the file). If you have a 16MB system, that value is 40MB; for a 32MB machine, that value is 80MB. You'll have to restart your  computer for the change to take effect.
 
What you need to know about computer, printer and graphics RAM ?
Whether you're adding memory to a printer, a graphics card or a computer, your upgrade choices are limited by the device in question.

Standard RAM chips for PCs are called Single In-line Memory Modules (SIMMs). SIMMs come in two sizes -- SIMMs that connect to the memory bank with 30 pins, and modules with 72 pins. Your use for either of these will depend on the type of machine you have. 72-pin SIMMs provide a 32-bit data path, matching the bus used on 80486 computers. Pentium PCs, however, use a 64-bit memory bus, so Pentiums need SIMMs installed in pairs in order to operate efficiently. SIMMs with 30 pins are found on older machines.

Today's Power Macintoshes and some high-end x86 PCs use Dual Inline Memory Modules (DIMMs), which can handle a 64-bit data path rather than the standard SIMM's 32-bit path. When installed in pairs, DIMMs support interleaved memory, with a 128-bit data path. Older Macs use SIMMs, and the technologies are not compatible: you can't put a new DIMM chip into a SIMM slot, and vice-versa.

Many printers use SIMMs, but just like computers, you need to be sure of your printer's memory configuration before buying a SIMM chip. Make sure it is compatible with your printer make and model, and that you get the right pin configuration. Check with the memory vendor or printer manufacturer if you have any questions.

Not all graphics cards provide slots for additional RAM to be installed, but if yours does, you can significantly increase the card's performance by adding some memory. Not just any RAM chip will work, however. Check the card manual or call the card manufacturer to find out exactly which RAM chips will fit.

You'll find a dizzying array of memory chips available, and product listings will spell out this variety in a number of different ways. But it's often a complicated process to figure out what kind of memory your system uses and what exactly you need to buy to upgrade it. If you're in doubt about what to get, contact the manufacturer or the memory vendor. They will be able to determine exactly what you need.

What you need to know about pin size in memory chips (Memory, Virtual Memory)
Standard RAM chips for PCs are called Single In-line Memory Modules (SIMMs). SIMMs come in two sizes -- SIMMs that connect to the memory bank with 30 pins, and modules with 72 pins. There are some DIMM chips that come with 168 pins, and RAM chips for graphics cards come with 64 pins.

The number of pins you need depends on the type of machine you have. 72-pin SIMMs provide a 32-bit data path, matching the bus used on 80486 computers. Pentium PCs, however, use a 64-bit memory bus, so Pentiums need SIMMs installed in pairs in order to operate efficiently. SIMMs with 30 pins are found on older machines.

Today's Power Macintoshes and some high-end x86 PCs use Dual Inline Memory Modules (DIMMs), which can handle a 64-bit data path as opposed to the standard SIMM's 32-bit path. When installed in pairs, DIMMs support interleaved memory, with a 128-bit data path. Older Macs use SIMMs, and the technologies are not compatible: you can't put a new DIMM chip into a SIMM slot, and vice-versa.

The number of pins is spelled out in product listings, and you'll have to do a bit of deciphering to figure just exactly what is being described. If the number after the x is an eight or a nine, it's a 30-pin SIMM. If it's a multiple of eight or nine, it's a 72 pin SIMM. Here are a few sample SIMM descriptions and their translation:

8x36-60ns 72 pins, 32MB, 60 nanosecond access time

4x36-60ns 72 pins, 16MB

2x32-70ns 72 pins, 8MB (no parity), 70 nanosecond access time

4x9-60ns 30 pins, 4MB, 60 nanosecond access time

1x9-70ns 30 pins, 1MB, 70 nanosecond access time

1x8-70ns 30 pins, 1MB (no parity), 70 nanosecond access time

What you need to know about parity in memory chips (Memory, Virtual Memory )
Parity checking, found on SIMM chips, refers to the way a computer ensures that stored data is not corrupted. SIMMs with no parity use eight bits to store each byte of data, while SIMMs with parity checking dedicate an additional ninth bit specifically for error detection.

Parity is mainly found on older machines since newer RAM chips are more reliable, making parity checking unnecessary. Make sure you specify whether or not you need parity when you are buying replacement SIMMs or are adding SIMMs to an existing machine.

SIMM product listings usually specify "no parity" in appropriate cases. Here are a few sample SIMM descriptions:

8x36-60ns 32MB (parity), 60 nanosecond access time

4x36-60ns 16MB (parity), 60 nanosecond access time

4x32-60ns 16MB (no parity), 60 nanosecond access time

2x32-70ns 8MB (no parity), 70 nanosecond access time

In most cases, the number after the x will be divisible by either eight or nine -- eight for SIMMs without parity and nine for SIMMs with parity.
 
What you need to know about the types of memory (Memory, Virtual Memory Management in general)
The most common memory technology today is dynamic RAM, or DRAM. Two major types of DRAM are used in SIMMs: Fast-Page Mode (FPM) DRAM and Extended Data Out (EDO) DRAM. While most older computers now use FPM, EDO is more common on faster Pentiums and on most new machines. Some vendors specify the type of DRAM on their chips; if you don't see it, you can always ask. Note that it is not always possible to mix the two technologies successfully.

The same clock that drives the RAM also drives the CPU. And since different RAM types operate at different speeds, you should correlate your RAM speed with the speed of your motherboard. If you install slow RAM on a fast motherboard, you will lose data because the RAM won't be able to keep up. On the other hand, installing fast RAM on a slow board won't hurt you, although it may be more expensive than it needs to be.

While EDO DRAM can operate as speeds of up to 50MHz compared with 40MHz for FPM, tests show EDO's speed increase to be minimal, according to Computer Shopper reviewers Alice Hill and Bill O'Brien:

Switching from FPM to EDO provided minimal if any enhancement to the computer's overall operations. Any gain that might have been achieved was too close to the tests' margin of error to note reliably.

Opting for FPM may save you $100 or so, if the vendor offers you the option.

Designer RAM Enhancements to the basic DRAM design have been made to increase speed and offer more speed and reliablity.

Burst EDO, or BEDO, is slightly faster than EDO, achieving speeds of 66MHz and higher and is found on many PCs. Error-Correcting Code (ECC) memory is a very reliable -- and therefore expensive -- type of EDO DRAM used on servers, multiprocessing machines and high-end workstations.

Synchronous DRAM is four times faster than standard EDO or FPM DRAM, but it is also more expensive. It works best on fast motherboards -- those that operate at speeds greater than 66MHz.

Other new types of RAM are being developed in order to keep up with the high processor speeds achieved by current and future processor chips. Rambus DRAM is now being used in a few computers, and can reach speeds of 500MHz.
 
Q:  What do the acronyms DRAM, EDO RAM and SDRAM mean,  and how does each type of RAM differ?
 
A:  DRAM stands for dynamic random access memory. As this type of  memory requires a constant current to retain information, it needs to be refreshed hundreds of times per second. The memory uses the same circuit to store and retrieve data, so access times can be an issue. Memory is organized in pages, and when one page is accessed, it takes                      additional CPU cycles to switch to another page to access more  memory.

EDO RAM stands for extended data out RAM. It's similar to DRAM,  but EDO RAM operates between 10 and 15 percent faster because it starts accessing the next block of data while sending the previous block to the CPU. That makes it easier and quicker to synchronize data transfer than with regular RAM. EDO RAM is used in both SIMMs and DIMMs (see the next question), while regular DRAM is typically found  only on PCs with SIMMs.

SDRAM stands for synchronized DRAM. It is significantly different from regular DRAM because it uses a clock cycle timing for data access and refresh. It operates at the same frequency as the system bus and synchronizes automatically with requests from the CPU. That  makes it faster than DRAM and EDO RAM. SDRAM is typically found only in DIMMs.
 
Q: What is the difference between SIMMs and DIMMs? And what are RIMMs?
 
A: SIMM stands for single in-line memory module; DIMM stands for dual  in-line memory module.

 RAM chips are typically packaged in 8MB, 16MB, 32MB or 64MB modules that plug into a PC's motherboard. These modules are small, standard-size circuit boards that hold the actual RAM chips. Memory  used to come in 30-pin SIMMs, but now you'll find these SIMMs only on  older PCs. Pentium-based PCs have the newer 72-pin SIMMs-which hold more memory and can access it better-or the newest DIMMs. DIMMS can hold even more memory and typically have 84 pins active on both sides for 168 connections.

While unbuffered DIMMs are limited to 64MB, newly designed  registered DIMMS can hold 128MB or 526MB. These registered DIMMs are found in servers and high-end workstations.  RIMMs, or Rambus memory modules, will be used with Intel's next-generation Rambus memory interface, which will support  high-speed buses and provide much greater bandwidth than current  memory (more on Rambus below).
 
Q:  Does the speed of my RAM matter?
 
A: The newer the system, the more RAM speed matters. On older systems  with SIMMs, speed matters less. A 60-nanosecond DRAM should work fine for all PCs, and some older systems can run on slower speeds of 70ns or 80ns.

SDRAM speed is measured in MHz because it is clocked, just like the system bus. Newer systems based on Intel's Deschutes Pentium II  processors use a 100MHz system bus and require memory clocked at  that speed. If your system uses EDO or SDRAM, make sure your RAM conforms exactly to the manufacturer's specifications. If you upgrade or replace RAM on a PC with DIMMs, you need to follow  exact instructions in your system manual.
 
Q:  Can I use my existing RAM in a new PC when I upgrade?
A:  If your new PC has a system bus clocked at 66MHz or slower, and the PC uses a compatible memory module (SIMMs or DIMMs), then it is  possible. Some systems are designed to take a mixture of SDRAM, EDO RAM and even DRAM, but many require a particular type of  memory. You should check the precise specifications of your new  machine.

If your new PC has a 100MHz system bus, you can't use the old RAM  (unless your old system had a 100MHz system bus). Make sure the RAM in the new machine is designed to run at 100MHz, or else you'll  see slower performance and even memory page faults that could crash  the system.
 
Q:   Is RAM for notebooks the same as RAM for desktop PCs?

 A:  Notebook memory chips are typically the same types of RAM as used  in desktop PCs, but with different packaging. Many notebooks use smaller SODIMMs (small-outline DIMMs). These come in 72-pin and 144-pin modules. But many notebook manufacturers use proprietary  memory modules, so if you want to expand RAM, you have to get  memory designed specifically for that machine.
 
 Q:  Is the RAM on a graphics card the same as regular system  RAM?
 
A:   Graphics cards have special requirements because they must simultaneously move data rapidly into and out of graphics memory to the display. Therefore, most graphics memory is dual-ported, meaning it can  send and receive data simultaneously. Graphics memory types include VRAM (video RAM), TPRAM (triple-port RAM), SGRAM (synchronous graphics RAM). Most current cards use SGRAM.
 
Q: What's cache memory? Can I upgrade it?
 
A: Cache memory is temporarily held data that's immediately ready to use,  speeding up your system. The Intel Pentium and many other CPUs have  this memory built right into the processor. That's level 1 cache, and you can't change it. Most CPUs now also have level 2 cache, used by the  main system RAM. Cache memory is much faster than regular RAM.

Static RAM is a type of cache memory that usually requires no refreshing or synchronizing and returns information to the CPU virtually  instantly. You can only upgrade cache memory if your system's cache  memory socket is accessible and includes a larger secondary cache as an option. If your system has a Pentium II, you have to replace the  entire processor to upgrade the cache because the system cache is  inside the processor's housing.
 
Q: What about future developments?
 
A: As CPU speeds increase, memory must become faster to avoid  bottlenecks. Two types of faster RAM are currently proposed. Intel is  backing Rambus or RDRAM, a much more complex type of memory interface using a special 800MHz bus and a protocol- and packet-based system for transferring data. Because Intel plans to eventually double the bus speed to 1.6GHz, Rambus is also likely to be the fastest of the  proposed suggestions.

A cheaper alternative is high performance SDRAM-DDR, or double-data rate SDRAM. SDRAM-DDR reads data at 200MHz, twice  the 100MHz speed of current high-end PC buses. An advanced version  of this, SLDRAM (SyncLink DRAM) will quadruple the data rate to 400MHz. The latter two alternatives are cheaper and easier to implement than Rambus. We may see Rambus in high-end PCs and SLDRAM in less-expensive systems.  None of the existing RAM solutions will transfer upward to these new  systems. The RAM you're using today isn't likely to work in the PCs of  tomorrow.

Check out these Web sites for more information on RAM.

                        http://www.corsairmicro.com/sdramfaq.htm
                        Corsair Memory answers Frequently Asked Questions about
                        SDRAM.

                        http://www.kingston.com
                        Kingston Technology, the largest memory retailer, offers
                        information, advice and products.

                        http://www.buymemory.com
                        Memory dealers McDonald and Associates' site includes more
                        explanation than most about what you may or may not be buying.

                        http://pcmech.pair.com/mbindex.htm
                        PC Mechanic's memory Web site offers RAM installation tips and
                        information.

                        http://www.rambus.com
                        Rambus Online contains information about Rambus memory.

                        http://www.tomshardware.com/ram.html
                        Tom's Hardware Guide's RAM Guide gives technical details of all
                        types of RAM.

                        http://www.sldram.com/home.html
                        The SLDRAM not-for-profit corporation's page includes information
                        on all you need to know about SyncLink DRAM.
 
 
Q: What kinds of video memory are there?
 
A: DRAM (dynamic RAM) is the basic type of video memory, but you  won't find it on high-quality cards because it's relatively slow. That's  partly because it can handle either a read command (processing data from your computer) or a write command (sending the data to your  monitor), but it can't do both simultaneously. The read/write demands might tax the card's capacity to refresh the monitor for high-resolution images, damaging performance.

EDO (extended data output) DRAM is faster and performs better with  more than 256 colors. Other types of video memory include VRAM (video RAM), WRAM (Windows RAM) and SGRAM (synchronous graphic RAM). VRAM and WRAM are "dual ported" so they can read    and write data concurrently. Increasingly, we're finding mid-priced graphics cards using SGRAM, which is cheaper than VRAM and  WRAM and faster than DRAM.
 
Q:  How much memory do I need?

A: The amount of memory determines how much detail you'll see on your  screen. Typically, you can buy 4MB and 8MB boards. With 4MB  boards, such as the Canopus Total3D, you usually top out at 1024x768 resolution when using true color (16.7 million colors). With 8MB boards,  such as the ATI All-in-Wonder Pro, you can often go as high as 1600x1200 in true color. Frequently, you also have a greater selection of  refresh rates available with 8MB boards. The price difference between
a 4MB and 8MB card is generally less than $50.  As a rule, 4MB-even 2MB-is sufficient for business applications. Game  players, CAD/CAM users and graphic artists will want 8MB boards.  And if you run extremely demanding graphics applications such as some advanced games, you'll find that a card like the new Diamond Monster
3D II-with 12MB of memory-can handle just about any graphics task. Of course, greater resolutions are only practical if you have a monitor  that's 17 inches or larger.
 
 
Q: What does refresh rate mean?

A: Vertical refresh rate refers to the speed at which an image is completely repainted on the screen. A refresh rate of 75Hz (the display is refreshed 75 times a second) is considered the bare-bones speed to avoid flicker. The higher the refresh rate at a given resolution, the better-flicker isn't  just annoying, it can cause headaches and eye strain
 
 

Q: I want to add RAM to my system. How can I tell whether I  need parity RAM or not? Also, some salespeople have
recommended something called logic parity. What is that, and  how does it differ from regular parity?

A: Parity is an old-fashioned technique for checking the contents of memory for errors. For every byte of RAM (eight bits), a ninth bit is added for parity checking. When a memory address is read by the computer, the parity bit is compared to         another parity bit calculated by the PC. If these two parity bits match, the data is assumed good. If they don't match, a fatal error is generated and the system halts to prevent further data corruption.

You can distinguish between parity and nonparity RAM by looking at the memory description on the SIMM. For example, you can tell that a 30-pin 2Mx9 SIMM has a parity bit because there are nine bits (x9) instead of eight; a 2Mx8 SIMM has no parity bit. Likewise, a 72-pin 4Mx36 SIMM also contains parity RAM because its 36 bits include four eight-bit bytes plus four bits left over, or one extra bit for each  byte. As a rule, SIMMs labeled x8 or x32 lack parity bits, while SIMMs labeled x9 or x36 have them.

There are several ways to tell whether your current system is using parity memory or not. First, check the system manual for the manufacturer's recommendations for RAM upgrades. If you don't have the manual handy, run your PC's CMOS Setup
and look under Advanced Chipset Setup for a memory-related entry such as Parity.  If parity checking is enabled, you should add parity RAM. If it's disabled, you could add nonparity RAM.

Another alternative is to check the part number on the SIMM board (not on the  SIMM's memory chips) against the online database of a major memory manufacturer such as Kingston (www.kingston.com) or PNY (www.pny.com). When you enter the  part number of your SIMM, the database will return a matching part and description that should include a parity designation. If you don't have access to the Internet, any computer store that sells memory should be able to help.

As for regular versus logic parity (also called fake parity), there is indeed a difference. Logic parity relies on a parity generator chip instead of memory tests. The chip provides parity bits that always match memory's contents. In effect, logic parity
lies to the motherboard. It only pretends to check parity, but provides no real  protection for your system. I don't recommend it.   Generally you can use parity RAM in a nonparity motherboard and vice versa, but only if you disable parity checking via the PC's CMOS Setup or a motherboard  jumper.
 
 
 

                                                        SOURCE:  Zdnet and Computer Currents