Some memory questions and answers

Does it matter which slots I plug my new module in?

In general, you will get the best performance if you put the largest module (in megabytes) in the lowest-numbered slot. For example, if your computer comes with 32MB of removable memory and you want to add 128MB, it would be best to put the 128MB module into slot 0 and the 32MB module into slot 1.

Looking to buy RAMBUS memory? Click here.

Why Does the Price of Memory Fluctuate?

Supply and demand. Occasional changes in market demands will alter inventories and, therefore, raise or lower prices.

Can you mix and match ECC and non-parity modules?

No. When adding new memory, you need to match what is already in your system. You can determine if your system has parity by simply counting the number of black memory chips on each module. Parity and ECC memory modules have a chip count divisible by three or five. Any chip count not divisible by three or five indicates a non-parity memory module.

Can DDR and SDRAM be used in the same system at the same time?

No. Even though there are systems that support both technologies, you can't have DDR and SDRAM in the same system at the same time. You'll have to choose one or the other.

"Have you ever gotten a "great deal" on a system and then been a little disappointed with its overall performance? If so, this article on Crucial's Web site is for you. Get the information you need to figure out whether or not upgrading your system would be worth the money.

What are MultiMediaCards?

About the size of a postage stamp, a MultiMediaCard, or MMC, is a small, removable storage device used in a variety of electronic devices, including digital cameras, handheld computers, and digital music players. MultiMediaCards are designed with flash technology, a non-volatile storage solution that does not lose its information once power is removed from the card. MultiMediaCards contain no moving parts and are extremely rugged, providing users with much greater protection of their data than conventional magnetic disk drives.

Does it matter which slots I plug my new module in?

In general, you will get the best performance if you put the largest module (in megabytes) in the lowest-numbered slot. For example, if your computer comes with 32MB of removable memory and you want to add 128MB, it would be best to put the 128MB module into slot 0 and the 32MB module into slot 1.

Why Does the Price of Memory Fluctuate?

Supply and demand. Occasional changes in market demands will alter inventories and, therefore, raise or lower prices.

Can you mix and match ECC and non-parity modules?

No. When adding new memory, you need to match what is already in your system. You can determine if your system has parity by simply counting the number of black memory chips on each module. Parity and ECC memory modules have a chip count divisible by three or five. Any chip count not divisible by three or five indicates a non-parity memory module.

Can DDR and SDRAM be used in the same system at the same time?

No. Even though there are systems that support both technologies, you can't have DDR and SDRAM in the same system at the same time. You'll have to choose one or the other.

"Have you ever gotten a "great deal" on a system and then been a little disappointed with its overall performance? If so, this article on Crucial's Web site is for you. Get the information you need to figure out whether or not upgrading your system would be worth the money.

What are MultiMediaCards?

About the size of a postage stamp, a MultiMediaCard, or MMC, is a small, removable storage device used in a variety of electronic devices, including digital cameras, handheld computers, and digital music players. MultiMediaCards are designed with flash technology, a non-volatile storage solution that does not lose its information once power is removed from the card. MultiMediaCards contain no moving parts and are extremely rugged, providing users with much greater protection of their data than conventional magnetic disk drives.

What is CL or CAS Latency?

CL stands for CAS Latency. It is a programmable register in the SDRAM that sets the number of clock cycles between the issuance of the READ command and when the data comes out. Smaller number for CL indicates faster SDRAM within the same frequency.

Several Memory module suppliers are offering PC133 modules with a performance setting of 3-2-2 . What advantage does a 2-2-2 module provide?

The first number of the 2-2-2 designation refers to CAS latency, so in short you are asking the advantage of a CAS latency of 2 over one of 3.

Adjusting a device to CL = 2 from CL = 3 will speed up a cc ess time from a READ command to the point at which data is available on the data bus (1 clock quicker).

Base on benchmark testing results, better performance improvements were found in the 2-2-2 setting over the 3-2-2 :

Are PC133 speed-tested SDRAMs backward compatible with PC100?

Yes. The AC timing specifications on a PC133 device are tested to allow a system bus to run at 133 MHz.

The PC100 and PC66 timing specifications are more relaxed on these timings.

Majority of PC133 chips should work at PC100 and PC66. In fact, a -75 device is specified for PC100 timings using CAS latency = 2.

Please refer manufacturer data sheet for AC timing table in the appropriate data sheet tCK at CL = 2.

If a SDRAM DIMM module is assembled with a -10 SDRAM chip, is it considered PC100 compatible?

No - An SDRAM DIMM with -10 (100 MHz) chip will support only 66 MHz Systems. This type of module is not guaranteed to run consistently in a PC100, 100 MHz system.

In order for the module to be PC100 compatible the components need to be marked with -8A, -8B, -8C, -8D or -8E (or 125 MHz)and example taken from micron chips.

Micron Modules with -8A through -8C sdram chips will run at 100 MHz at a CAS latency of 3.

Modules with -8D or -8E components will run at 100 MHz at a CAS latency of 2.

Refer to the original manufacturer data sheet to
determined the correct CAS latency setting.

What's the difference between buffered and unbuffered DIMMs?

High density DIMMs have lots of chips on them and therefore possess a higher capacitive load on the address and control signals in comparison to lower density DIMMs. Some designers use re-drive buffers on the DIMM to boost the signals to reduce system loading when compared to the same high density module without buffers. But,
the buffers introduce a small delay into the electrical signal, so adding buffers to a standard density module would have the effect of slowing down the signal, compared to the same low density module without buffers.


What is the difference between 72 bit and 64 bit memory?
What is the difference between 32 bit and 36 bit memory?

72 bit memory is commonly known as ECC memory. It has an additional 8 bits for Error Correction Check 64 bit memory is non-ECC. 72 bit or 64 bit
configuration are typically found in 168 pin DIMMs

36 bit memory is commonly known as parity memory. It has an additional 4 bits for parity checking. 32 bit memory is non-parity. 32 bit or 36 bit configuration are typically found in 72pin or 30 pin SIMMs

Can you tell by looking at a module if it is SDRAM, FPM, EDO etc?

SDRAM, EDO and FPM chips look similar to each other. 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. By looking at a memory module one can attempt to guess what it is. A general guideline is to look at the IC type and size. The EDO and FPM chips are typically packaged in SOJ form and are thicker when compared to that of the SDRAM chips which are typically packaged in slim-line TSOP form. The EDO/FPM chips typically have a marking of -60 at the end of the string of numbers and that of the SDRAM chips typically have markings of -12 -10 -8 -7.5. A SDRAM module typically has a row of the resistor or resistor arrays above the contact tabs.

What is refresh rate and self refresh?

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 cycle refers to the number of rows that must be refreshed. The common refresh cycles are 2K, 4K and 8K. Refresh cycle together with refresh period determines how often refresh is needed, which is defined as Refresh Rate. For the same refresh period, 4K
refresh parts needs to be refreshed more frequently than 2K parts. For the same size DRAM, 4K refresh
part consume less power than 2K refresh parts. 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


What is PC SDRAM, PC100 SDRAM and Registered SDRAM?

PC SDRAM is a loose general term for SDRAM that runs at 66 MHz and has an SPD chip for compatibility with P-II motherboards.

PC100 SDRAM refers to PC100 SDRAM chips or DIMMs that meet INTL PC100 qualification standard. These parts are designed to run at 100
Mhz front side bus (FSB) speeds.

Registered SDRAM - This is SDRAM module with Register for Address and Control Signals. Registered DIMMs reduce the loading of DIMM to the motherboard so that larger capacity DIMM modules and more DIMMs can be populated on a motherboard. It is a technique used widely on servers to increae the amount of memory the system can support. The Registered DIMM is a little slower in a cc ess timing versus that of the unbuffered counterpart.


What happens if my memory is not PC-100 compliant?

It means you may experience system errors in a 100mhz system because the memory's performance cannot keep up with the system requirement. The system will operate at the speed of the slowest component. For example, installing 66MHz SDRAM memory in a PC-100 system will cause the bus to operate at 66MHz, rather than the speed it was designed to operate at.


How can I recognize compliant PC100 or PC133 SDRAM memory?

A PC100 or PC133 compliant memory includes a label affixed to it which identifies the module as "PC100 compliant" or "PC133 compliant " . An attempt can be made to verify it by looking at the chip marking which should indicate "-8" or "-7.5" after the string of manufacturer part number, though this may not be entirely a cc urate.


What voltage is SDRAM?

SDRAM specifications state that all SDRAM has to be 3.3V.

What is the difference between "2-clock" and "4-clock" SDRAM?

The early SDRAM DIMM design has 2 clock inputs to drive all the SDRAM chip. This was found to be insufficient due to loading on these inputs. Some 4 clock modules will not work in systems that are designed for 2 clock, but some will. SOME 2 clock modules might not work in systems designed for 4 clocks, but then again some will.

4 clock modules are the current standard and it is unlikely to change again.

What is the performance difference between EDO DRAM and standard (Fast Page Mode) DRAM?

EDO DRAM speeds up memory transactions by as little as 5% or by as much as 25% over conventional DRAM, depending upon how much Cache you have on your motherboard. Less Cache on the motherboard will result in a larger speed increase when adding EDO DRAM. EDO eliminates a wait state between the execution of sequential-read commands from memory, giving the CPU significantly faster a cc ess to memory.


What's the difference between 2K and 4K SDRAM?
In Short : not much, don't worry about it.

Well the truth is :
The SDRAM has multiple internal banks. The 16M SDRAM has 2
banks, the 64M has 4 banks. When you tell the SDRAM a ROW or COLUMN address you must also specify which BANK you are referring to. The way to do this is by the 'bank address' (BA). Herein lies the problem. For some unknown reasons, suppliers have lumped together the ROW address pins with the BANK address pins and simply refer to them as 'address' pins. For the 2Mx8 SDRAM some suppliers claim to have 11 ROW address plus 1 BA, other just say 12 addresses. That's just addressing, for refresh requires you also specify the refresh interval (
tREF ). For a distributed refresh scheme you simply divide tREF by the number of refresh cycles to get the auto-refresh interval. In both cases for the SDRAM it works out like:

Address bits Refresh Cycles tREF Auto-refresh interval
11 row 2^11 = 2048 = 2K 32ms 32ms / 2048 = 15.6 us
12 2^12 = 4096 = 4K 64ms 64ms / 4096 = 15.6 us

The upshot is that for distributed refresh schemes these two devices are identical in both addressing and refresh. (For a burst refresh scheme, the 32ms tREF is a subset of the 64ms.)

For the general PC application the 2K device works fine. The 4K device offers no advantage. Note that this is not the case for asynchronous DRAM where there truly is a difference in addressing between 2K and 4K.


What Memory does Apple MacIntosh Computers use?

Mac Quadra 700, 900, 950, and MacIntosh II series computers use 30 Pin SIMMs. Installation requires 4 SIMMs per bank of the same value.

Mac IIfx uses 64 Pin SIMM modules.

Mac Plus, Mac SE, Mac Classics, Classic II, Color Classic, Mac LC, LCIII, Performa 200,400, 405, 410, and 430 utilize 30 Pin SIMMs.

New Quadras , newer Performas , and
Centris series utilize 72 Pin SIMMs.

Most MacIntosh computers come with onboard permanent memory and can utilize 72 Pin SIMMs 1 at a time.

Mac Performa 6400/180 & 200 models require 168 Pin DIMMs to upgrade.

Memory Type: Fast Page Mode DRAM

Pentiums Computers (586 Computer)

Majority of the Pentiums computers have 2 banks of two SIMM sockets on the motherboard, each bank must have a pair of same value and type of memory to be utilized by the system.

Most Pentiums computers
uses 72 Pin SIMMs. Installation requires 2 SIMMs per bank to upgrade. (2 sockets per bank)

Typically, Pentiums Computer with frequency of 166MHz and up have SIMM and DIMM sockets on board and use 168 Pin DIMMs and 72 Pin SIMMs on the same motherboard.
Pentium computers utilizing 168 Pin DIMMs require 1 DIMM at a time, (1 socket per bank.)

Memory Types: Generally EDO (extended data out) DRAM in matching pairs. Older Pentium computers (60MHz -100MHz) require FPM (Fast Page Mode DRAM.) Newer 100MHz to 200MHz MMX computers, CYRIX 6X86 and AMD 586 class processors uses EDO or FPM, and in some machines SDRAM (DIMMs.)


486 Computers

Most 486 DX computers uses 72 Pin SIMMs. Modules may be installed singlely ie one SIMM at a time or 1 socket per bank

Most 486 SX computer utilize 30 Pin SIMMs. Modules must be installed in 4 pieces at one time or 4 sockets per bank.

Some 486 computers (both SX & DX) utilize both 30 Pin and 72 Pin SIMMs on the same motherboard.

Memory Type: (FPM) Fast Page Mode DRAM, both Parity or Non-Parity, depending on the motherboard requirements.

386 Computers

Majority of 386 computers uses 30 Pin SIMMs, though some 386 computers may use 72 Pin SIMMs.

On 386 computers, Modules must be installed in pairs. Insert two pieces of 30 Pin SIMMs per bank.

Memory Type: Fast Page Mode (FPM or FM)

How much memory do i need?

Very Good Question :-)) These days, when one buy a PC, it's primary intended purpose is for speed and performance especially capable of incredible performance for huge graphic and multimedia application. In order for smooth efficient operation of PC with these new memory hungry softwares, a lot more memory is required. In the past, 8MB or 16 MB or 32MB used to be plenty enough, but with software program increasing in size, 64MB is the least that a Windows based PC would require. Today's PC are being shipped with minimum 64MB and even 128MB installed. If you plan to take advantage of the latest technology developed into new software, you should either choose to upgrade your PC's memory or buy one with at least 64MB or more pre-installed.

How do I know when I have enough memory?

Determining your needsThe amount of memory you need is determined by several factors; the software, operating system and the number of programs you want to have open at the same time. When you determine memory needs, you'll also want to consider what your needs will be six months down the road. If you think you may be upgrading your operating system or adding more software, it's a good idea to factor that into the equation now. The following user profile will also help guide your decision:

Business user (64MB-128MB)
~~~~~~~~~~~~~~~~~~~~~
Light to Medium usage:
runs 2 or 3 applications at one time. Mainly used for word processing, e-mail, fax and communication, database type of application

Home multimedia user (64MB - 128MB)
~~~~~~~~~~~~~~~~~~~~~~~~~~
Light to Heavy usage: runs 2 or 3 applications at one time. Mainly used for word processing, e-mail, surfing the internet, with Heavy user may include use of database, Graphics & 3D intensive games.

Graphics user (128MB - 512MB)
~~~~~~~~~~~~~~~~~~~~
Light to heavy: runs 3 or more applications at one time. Graphic page layout, illustration/graphics. and Heavy users also need photo editing, font packages, multimedia and presentation software.

CAD Design (256MB - 2GB)
~~~~~~~~~~~~~~~~~~
Light to heavy: CAD and CAM software. Heavy users need 3D CAD and solid modeling CAM .


How Much Memory Do I Have?

It's easy to find out how much memory your PC has :

1. From your User/Owner's Manual
Consult your user/owner's manual for details about the original memory configuration and capacity. If you've misplaced the manual, you may be able to contact the retailer where you bought the PC from.

2. If you have a hand-me-down PC or inherited a pre-owned PC, you probably may not have the user manual or know any detail of the original memory configuration or the memory configuration may have been changed. Then you may want to try one of the following options:

2a) Ask Your PC
If your PC is running Windows NT/98/95, use the right mouse-click on "My Computer" then select "Properties." The total memory is calculated and displayed under the Tab that shows "General" in the system property dialog box.

If your PC is running Windows v 3.1 or older, go to the DOS prompt and type in "MSD."

2b) Ask Your Mac
If you're a Mac user, select "About This Macintosh" or ("About This Computer") from the
Apple menu on the upper left corner of your Desktop. This will provide info rmation about
your Mac's total memory (built-in memory plus DIMMs or SIMMs installed).


General Guidelines for Memory Upgrade Based on CPUs

This section provides a general guideline on memory upgrades based on your computer systems CPU. This is intended as a broad guideline. Please consult your system user manual for further details of your system requirement


Do I need PC100 SDRAM for my PC system?

Yes, only if you have a 100 MHz system bus. No ,if you have a 66 MHz system bus. On certain system, a non-PC100 module may be "pushed" to run in a 100 MHz system, but the results are not guaranteed and may lead to system instability.

Pentium Pro Computers (P-6 Processor)

Majority of Pentium Pro P6 Computers uses 72 Pin SIMMs. Installation requires 2 SIMMs per bank to upgrade memory. (2 sockets per bank)

Memory Types: Parity or Non-Parity FPM or EDO (Most have been configured with Parity FPM)

Will more memory speed up my computer?

More memory will not increase the speed of the CPU, but it will reduce the time a CPU spends waiting for info rmation from a hard drive. Since RAM provides data to a CPU faster than a hard drive, you will not have to wait as long for programs to execute.

Installing and Removing Memory Module. Replacing defective modules and upgrading to new modules

Things needed
- new memory modules
- screwdriver (pc case removal)
- pc user manual or guide

Tips on Memory Module Installatioon

1. ensure environment is static safe by removing any unwanted plastic, bags from your workbench. Keep the computer system plugged into your AC unit but ensure that the power switch on the PC is turned off. Keeping the PC plugged in the AC will ensure that case is grounded thus reducing the possibility of damaging the module or system from ESD (Electro Static Discharge )

2. After removing the casing cover, ground yourself by touching any of the metal surfaces on your computer casing. Doing this step discharges any static built up on your body and
clothings

3. Visually locate the computer memory expansion slots. This is normal visible but if in doubt, refer to your operation manual instruction book.

4. Insert memory upgrade a cc ording to illustration in guide. Take note of
- modules keyed notches and match to socket

5. Replace case to complete installation.

Note: when restarting your computer, note any error messages that is being displayed and update your configuration setting a cc ordingly.

How many modules do I need to upgrade my Pentium?

Pentium motherboards require the installation of matching pairs when using 32 or 36 bit 72-pin memory. The motherboard is 64 bit and would necessitate the use of two 32 bit or two 36 bit modules to equal the 64 bit
mainboard .

I just installed 16MB of memory in my 486. I turned on the computer and get a message: Invalid configuration/run setup. How do I fix this error?

This is not an error. This is exactly what should happen when installing memory. Your system "sees" the new memory, but your BIOS
does not. You must run the CMOS setup utility to allow the BIOS to 'write' the changes in extended memory to the CMOS setup. There are several ways to a cc ess your setup, but the normal method is to hit your F1 or F2 key when you first boot up. Some systems require Control+Alt+Esc , while others require the delete key to enter setup. Check your manual for the exact key strokes.

I installed EDO memory in my Pentium system and am now encountering boot-up problems

Try installing the EDO modules in the bank containing the OEM (original) factory SIMMs and moving the OEM SIMMs to another bank. Many times this will resolve the conflict. If this does not resolve your problem, you may need to exchange the EDO modules for Fast Page Mode (FPM) memory available at your place of purchase. Also remember, EDO memory does not work in 486-based systems.

I have just installed memory into my 486 and have a blank monitor or the system refuses to boot. What's wrong?

Make sure you are not trying to install EDO memory into your system. EDO will not work in the 486 based computer .

Will EDO modules work in my 486DX2-66?

No. EDO memory is designed for Pentium style motherboards (64 bit) and will cause errors or no-boot if used in a 486 system. Install 72-pin non-EDO memory.

What is the difference between EDO memory and Fast Page Mode memory?

EDO memory has a faster read timing than FPM but has the same write timing. FPM is commonly used in 386 and 486 computers, while EDO is for Pentiums only. Apple computers should be configured with Fast Page Mode memory.

I want to purchase Fast Page Mode memory for my 486 computer, but the retailer only has EDO and Parity memory. What do I purchase?

EDO memory will not work in 486 computers. Parity memory, which is actually Fast Page Mode with 4 bits for parity checking, works in all computers. If your system does not use parity, it will ignore it. However, if your system does require parity, then you must use parity modules. Newer Pentium systems can be configured to use either parity or non-parity modules but need to have the BIOS set up a cc ordingly.

My Pentium 100Mhz computer came with EDO memory. I installed two new EDO 60 nanosecond SIMMs and now my screen is blank when I boot the computer. Why?

Generally speaking, EDO is for Pentiums 120Mhz and up. Most early Pentiums (60MHz -100MHz) prefer Fast Page Mode (non-EDO) memory. Some earlier Pentiums can use EDO , but it may require replacing the slower standard EDO memory, and changing your BIOS. This is not recommended for most users.


I own a Pentium 200MHz computer which has SDRAM memory. I have one memory slot available on the mainboard for upgrading. Do I have to remove the existing module and install in matching pairs to upgrade my memory?

No. SDRAM or Synchronous DRAM systems utilize 64 bit, 168-pin DIMMs rather than 72-pin SIMMs. Leave your existing memory and install one additional module. (168-pin DIMM) Make sure the memory is SDRAM.

What is ESD ?

ESD (Electrostatic Discharge) is Static electricity . This energy is found in air surrounding us and can damage electronics components in a computer such as Harddisk drive, Floppy Disk drive , motherboard , CPU, memory modules etc.. ESD o cc urs when one touch an object that conduct electricity.

To protect your memory module from getting damage by ESD, always keep electronics components in AntiStatic packaging until ready to use.

If I have regular memory sizing error during POST ( bootup), how should I trouble shoot the failure ?

One of the most common memory problem faced in older PC system during boot-up is “incorrect memory sizing” or the error number 164. Sometimes failures could be caused by incorrect software setting, sometimes it could be caused by hardware – which could be easily fixed if you know where the faults lies.

In most cases hardware failures are caused by the natural aging process of the memory components, defective memory module socket, dirty contacts, cold solder joints during assembly and memory module not seated properly in the socket due to vibration.

It is important to pay attention to intermittent memory failure, before you make any expensive decision to replace the expensive memory - try cleaning the memory module contacts for both old and new ram to see if the problem can be fix:

Here ‘s the How to :

Things needed
– Contact Clean (Purchase from local computer hardware store)
- Cotton Bud ( For cleaning contact with)
- Screwdriver (pc case removal)
- PC user manual

1 - ensure environment is static safe by removing any unwanted plastic, bags from your workbench. Keep the computer system plugged into your AC unit but ensure that the power switch on the PC is turned off. Keeping the PC plugged in the AC will ensure that case is grounded thus reducing the possibility of damaging the module or system from ESD (Electro Static Discharge)

2 -After removing the casing cover, ground yourself by touching any of the metal surfaces on your computer casing. Doing this step discharges any static built up on your body and clothing

3 - Visually locate the computer memory expansion slots. This is normal visible but if in doubt, refer to your operation manual instruction book.

4 –
the first thing to do is to remove the memory module and perform some visual inspection to check the memory socket which sits the memory module. Make sure all the pins are straight, no cracks or broken pins must be found.

A Wet the end of a cotton swab with the solvent, the swab should be wet but not dripping
B Using a circular motion, clean the contacts on the memory module.
C Allow the contact surface to dry thoroughly.
D Replace the memory module into the socket.
E Repeat steps B through D for each module you have.
F Power on the computer to test the RAM.
G If you see no memory errors, replace the PC's case and power-up away.

Additional Tips:

5. While contact cleaner is preferred, it is also a well-known trick that you can also clean contacts with a pencil eraser.
6. Continuing RAM errors are usually a sign of a bad memory module. If cleaning the contacts doesn't solve your problem, try to isolate the faulty module and replace it.

Troubleshooting Memory Failures using AMI BIOS Beep Codes

AMI BIOS is the most popular BIOS used by most motherboard manufacturer- you should be able to determine your system BIOS by reading the screen display on the Top screen during power up.

Procedures – The normal procedure is to power up the PC system, watch for error message on the monitor screen and listen to the PC beep tone. A single beep during boot-up process is normal and does not indicate a failure if the system continues to boot-up.

1 Beep tone - DRAM refresh failure
2 Beep tone - DRAM Parity failure
3 Beep tone - Base 64K RAM failure
4 Beep tone - System timer error
5 Beep tone - CPU failure
6 Beep tone - Keyboard controller error
7 Beep tone - Virtual mode error
8 Beep tone - Display memory read/write error
9 Beep tone - ROM BIOS checksum error
10 Beep tone - CMOS register read/write error
11 Beep tone - Cache memory error
Continous Beep tone - Memory or Video memory failures

Guide to Troubleshooting memory using BIOS Beep Codes

The BIOS on the motherboard will always perform a power-on-self-test “POST” during power up, usually this test is perform to ensure proper system function and if a failure o cc urs – the “POST” will identify the failure and emits a beeping sound to prompt the service technician to take corrective action ASAP.

The exact meaning of the beeping codes varies from different BIOS
developers, there are 3 basic BIOS developer today, the most popular BIOS is made by “American Mega-trend” - AMI, Award and Phoenix BIOS. The beep codes for this AMI & Award BIOS developer are provided in this memory troubleshooter guide, we do not provide beep code reference for Phoenix BIOS and custom BIOS written by other companies other than the two
mention .

Beep codes are not entirely consistent sometimes to detect the exact failures, but generally it is still the most dependent methods to diagnose a fault without opening up the PC system or using any diagnostic software.

My PC boots up okay but seems to hang up after running for one hour or so. How can I find out what is wrong?

Well, this is tricky situation. Typically you may want to begin by finding out if it's a memory related problem. DocMemory PC Memory Diagnostic software is designed for this very purpose. You can start by downloading a copy of the
sofware from
DocMemory Diagnostic Site , follow the setup instructions and run a diagnostic test on your PC memory.

If all Memory tests results returns good, you will need to isolate and examine other possiblities such as CPU, Motherboard or other peripherals that you have in your PC.


Some techniques for troubleshooting Memory failure without a Memory Tester. You can attempt the following experiment:

Removing the modules one by one from motherboard
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is simplest method for isolating a failing module, but this may apply only if the motherboard have more than one module on the SIMM or DIMM Slot. By selectively removing module one at a time from the system and then running the test you will be able to find the bad module very quickly. Be sure to mark the module that passes or when it test fails.

Swap the modules around
~~~~~~~~~~~~~~~~~~~~~
When none of the modules can be removed, swap and rotate modules to find which module is defective. This technique can only be used if there are two or more modules in the system. Change the location of two modules one at a time.

For instances, place the module from SIMM slot 1 into slot 2 and place the other module from slot 2 in slot 1.
Run the diagnostic test and if either the failing data bit or address changes, you know that one of the module you have just swap is defective. By using several combinations of module swapping you should be able to check which module is defective.

Replacing with known good module
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you are unable to use either of the above two techniques, you are left to use known good modules and selectively replace of modules one by one to pin point the memory failure. This is the easiest way to detect memory failure.

Removing and cleaning the metal contacts
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If your PC system is older, sometimes dust and oxidation will cause poor contact in the SIMM/DIMM slot. Remove the module and clean the gold or tin contact with a “pencil eraser” or any cleaning solution used for video and audio head cleaning. Make sure you remember which slot is being used, and be careful not to reverse the module while reinserting into the SIMM/DIMM slot

Identifying memory failure using motherboard BIOS codes
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you are not trained to perform the correct diagnostic methods – majority BIOS developers and motherboard manufacturers have device a simple way of telling you if your system is having problem by emitting beeping tones from the build in speaker on the motherboard, without the aid of a memory tester.

How do I clear the printer memory after each page is printed

1. Open the file wanted to be printed.

2. Click on File, Print, or simply press "Ctrl P".

3. In the Current Printer box, click on the Select menu bar.

4. Click on Setup -> Options -> Advanced

5. Click on the Clear Memory per Page check box.

6. Close and Click on Print to print the file, or return to the current file by clicking on Close.

Guide to Troubleshooting Memory Failures without a Memory Tester

This section is written with the assumption there is a general understanding of PC operating system, in order for you to be capable of performing the diagnostic procedures detailed below.

We will try to describe the entire process in full detail, however it is beyond the scope of this troubleshooter guide to provide all the necessary info rmation to cover all possible PC system failures. For further assistance with non-memory related failures, please consult your PC manual or manufacturer support help online system. If your particular question is not addressed in this section – please send us an e-mail and we will do our best to provide you with the right answers.

When you are experiencing memory failures on your PC system, there are several faults to determined, check the following:

* PC system does not boot-up
* HIMEM.SYS does not load
* Memory failure due to system hanging up, or system rebooting after running a large program.
* Fail to install win3.1, Win95 and Win98
* Windows program is unstable
* Continous beeping sound emitted by system during power up
*
Continous ram count during boot-
up , without loading Windows program
* No display other than blue screen on the monitor during boot-up
* Totally no video display on the monitor.
* System hang or rebooting after prolong usage.

All of the above are typical of memory related failures, you need to be either well trained or PC knowledgeable to be able to perform the correct diagnostic methods.

Once a memory failure has been detected, identifying the defective module is not an easy task either. With a large variety of motherboard provided by different manufacturer around the world, and with the many different combination of SIMM/DIMM slots provided, it would be difficult if not impossible to assemble a complete info rmation about how a particular memory error would map to a failing memory module.

However, there are some basic rules that may be taken to pinpoint defective modules using a memory diagnostic software as an aid.

Troubleshooting Memory Failures using Award BIOS Beep Codes

Award is the another popular BIOS developer and they use the fewest beep codes by far.

Procedures – The normal procedure is to power up the PC system, watch for error message on the monitor screen and listen to the PC beep tone. A single beep during boot-up process is normal and does not indicate a failure if the system continues to boot-up.

1 Long Beep tone - Memory Problem
1 Long Beep and 2 Short Beeps - DRAM Parity failure
1 Long Beep and 3 Short Beeps - Video error
Continous Beep tone - Memory or Video memory failures

SDRAM FAQ's

What Speed to use for Intel chipsets

440LX - max 1GB, PC66 SDRAM

450NX - max 8GB, PC100 SDRAM

440GX - max 2GB, PC100 SDRAM

440BX 440ZX - Use PC100 SDRAM

What Is Synchronous DRAM?

Synchronous DRAM's transfer data in

lock step with the rising edge of an applied square wave shaped clock signal (the same clock signal that operates the memory controlling chip set). Since the timing of synchronous DRAM is very predictable, data can be transferred at a much higher rate than was possible with older technologies such as EDO or fast page mode DRAMs.

What is PC100?

PC100 is a specification for SynchronousDRAM memory modules originally published by Intel. The specification describes, in extraordinary detail, the requirements for an SDRAM module operating at 100 MHz.

What is PC133?

PC133 is a specification for a 133 MHz Synchronous DRAM memory module. It is an enhancement to the original specification for PC100 memory modules.

What is the difference between PC100/PC133 and Rambus?

Rambus memory modules use an entirely different electrical interface than PC100/PC133 modules. PC100/PC133 modules transfer data at 100 (133) MHz over a 64 bit wide interface (72 bits when using error correction). Rambus modules transfer data at 800 MHz over an 16 bit interface (18 bits when using error correction).

Rambus is capable of transferring data at twice the overall rate of PC100 modules (the clock is 8 times faster and the interface is 1/4 as wide).

What is Double Data Rate SDRAM?

Double data rate SDRAM transfers data on both rising and falling edges of an applied square wave shaped clock signal. Therefore, a PC266 DDR memory module can transfer data twice as fast as a PC133 SDRAM module.

What is ECC?

Typical memory controllers read and write 64 bits of data at a time to and from memory modules that do not support ECC. 8 additional bits are required to support ECC (72 bit memory modules). Systems using ECC (Error Detection and Correction) can automatically correct any single bit error in any of the 72 bits. They can detect two bit errors. ECC is used in mission critical applications so that the system will not crash if a memory cell loses data.

What are registered modules?

There are two types of SDRAM module organizations, unbuffered (also known as unregistered) and registered. Registered modules have additional components (registers) placed between the incoming address and control information and the SDRAM components. These modules are typically used in Servers due to their added reliability (they place much less of an electrical load on the memory controller and therefore make it possible to have as many as 16 or 32 modules in a large system).

What is Serial Presence Detect?

Serial Presence Detect (or SPD) information is stored inside of a special component on the memory module. The component is called an EEPROM. The information is read by the computer's BIOS during boot to tell the computer how to properly configure the memory controller for the memory modules that are installed in the system.

What is CAS Latency?

CAS latency refers to the number of clock cycles between the application of the SDRAM's column address and the appearance of the data at the output of the module. It serves as a performance indicator. A CAS latency 2 module requires 2 clocks between the application of the column address and the data. This is one clock faster than a CAS latency 3 module. Systems using CAS latency 2 (CL2) SDRAM's are typically a few percent faster than systems using CAS latency 3 SDRAM's.

Memtest-86 3.0

http://www.memtest86.com./

MemTest v1.2 [9k] W9x/2k/XP - free - http://www.mywebattack.com/gnomeapp.php?id=105570 and

http://www.simmtester.com/page/products/doc/download.asp