1. NT1110
Unit 6 1

2. Unit 6 Objectives RAM Basics. RAM Types. Operational Characteristics.
Describe what RAM does, how it works, and how it relates to the system.
RAM Types.
Describe types of RAM available, including SDRAM, DDR, and Rambus.
Operational Characteristics.
Describe the features of memory modules and types of memory like ECC, EDO, registered, and unbuffered.
Installing Memory Modules.
Demonstrate how to install SIMMs and DIMMs properly.
Troubleshooting Memory.
Describe issues with RAM due to incompatible memory speeds and types.
Preventative Maintenance for Memory.
Describe measures to take to keep memory modules clean and protected. 2

3. Random Access Memory Random access:
Means that memory addresses are dynamically allocated.
Different from ROM in which memory addresses are pre-assigned to specifically coded functions.
What role does RAM play?
Provides CPU with data to process:
Keyboard entries are sent to RAM addresses.
Hard drive programs are sent to RAM addresses.
Network data (web pages) are sent to RAM addresses.
RAM is faster than other storage, such as hard drives and USB memory.
Installing more RAM is often the easiest way to improve system performance without investing in a new system.
Instructor Task #1: Establish Relevancy
Distinguishing RAM from Other Types of Memory
Somehow RAM has become more complicated. New bus speeds, processor capabilities, and sheer size has blurred what was once one of the easiest things to do, which is to install more RAM on the motherboard. Unlike the restrained (that is, low cost) perspective of the author often used in this instructor's guide, RAM is one area where more is usually better. Even if your operating system can only use 3GB, how long will it be before we are all using 64-bit operating systems and are installing GB on the board routinely. So, to answer the question of why do we care, we care because the first time our patience is tested by a print spooler taking 15 minutes to start printing a single 10 MB photograph, we will care. So, here are some "beginning of lesson" questions to ask students to get their minds thinking:
How do you know how much RAM you should order on a new PC?
How do you know how much RAM you have on the current PC?
How do you know when you do not have enough RAM?
How do you know what kind of RAM to buy?
These are all questions a technician will be asked and will need ready answers for both in real-world applications and on the certification exam.

4. RAM Specifications to Know (Before You Buy)
Module type:
Number of pins and placement.
Number of RAM slots available for modules.
Number of RAM memory banks required per module.
Dual and/or triple channel support.
Chip type:
SDRAM, DDR, RAMBUS.
Speed:
Needs to match up as multiple of motherboard front-side bus speed.
Error checking:
Optional, but often purchased in conjunction with database servers.

5. RAM Types SRAM = Static Random Access Memory:
Also known as L1, L2, L3 cache memory.
Does not require a memory refresh.
Used with CPU to store frequently accessed data routines.
Very fast, but very expensive.
Not generally upgradeable.
SDRAM = Synchronous Dynamic Random Access Memory.
DDR = Double Data Rate.
DDR2 = Double Data Rate (enhanced).
Rambus.
Analogy: The Importance of Primary Storage
Imagine that you work in an office with a cafeteria downstairs. However, you have a very busy schedule and don't always have time to get a proper lunch. One option would be to keep a small supply of food and liquid in a small fridge in your office. This obviously is not the larger menu at the cafeteria, but it might be an easy-to-reach version of your favorites and mid-morning snacks.
Likewise, the CPU makes access of what is known as primary storage. There are two types of primary memory storage. One is directly attached to the CPU itself and is called the CPU cache. This cache is directly accessible without making a trip across the north bridge to the larger RAM supply of memory addresses. The cache is like your office fridge containing the most commonly used programming routines (like your snacks) needed by the CPU based on its recent history of user requests. The cache is divided into sub-categories of L1, L2, and L3, with L1 being the mostly frequently used sub-routines. The RAM is the larger cafeteria where active programs are stored based on user preferences. (Put the RAM and cache into a table category as depicted next.) For an example of how this works, have you ever noticed that the first time you click on a seldom-used option in Microsoft Word, such as the "bullet" button, it takes a smidgen longer to execute itself than it does after that? The second time you use it, the CPU has copied it into the cache for quick execution. After a while, it returns back to RAM to make room for other sub-routines being used more frequently.
Ask students, "Now that you know where the CPU stores data, where do we humans store computer-generated data?"
Answers will vary but use your display/chalkboard to enumerate them and place them into categories like that shown in Table 6.1.
Table 6.1
Primary StorageSecondary StorageTertiary StorageOffline/Portable StorageRAMHard DriveInternet StorageUSB Memory StickL1/L2/L3 CacheRAID SystemNetwork File ServersCD-ROMFlash /Solid State Optical JukeboxesESata Drives
Which of these data storage types are the fastest? (Answer: memory cache and RAM)
Explanation: This discussion will hopefully point students in the right direction for balancing the resources of the CPU, motherboard speed, and RAM speed so as to optimize the investment in all three.
Speed of access is why the L1/L2/L3 cache and RAM are the sequence of choice from which the BIOS can directly load programs and store temporary data. Hard drive arrays and Flash memory are much slower by comparison. With today's multi-core processors, even RAM is slow, which is why you need to pay attention to the amount of onboard cache when you buy a processor. This cache allows the CPU to be more efficient with the least amount of delay in processing. This is especially important when running graphically intense programs, such as games and game development tools, but not so important for more stagnant programs, like the one that created this manual.
You might also point out that every computer has a bottleneck. Figuring out exactly what that bottleneck is can be a kind of board game (excuse the pun) for chip manufacturers. One year, the CPU is the bottleneck; the next year, the memory is the bottleneck, then the bus, and then the hard drive (hard drives also have memory caches). Something is always going to be the slowest link in the sequence. This slowest link will then drive innovators to improve it. That causes technology to keep changing.
Where does the RAM get its data from? The answer is secondary storage. Just like the cafeteria must order menu-driven food items from its suppliers, RAM is a temporary location to store data while it is waiting for the CPU to request it. The data is permanently stored into secondary devices like hard drives, which while comparatively slow, can keep data for long periods of time at low cost and without the need for the electrical refresh that RAM requires. More recently, we have seen hard drives being replaced or supplemented by solid state memory. There may even come a time when you buy your operating system from Microsoft (or others) on a chip that is plugged directly into the motherboard on the north bridge (that is, instant on). It would be linked back to the OS provider's servers using the Internet, and you simply pay a small yearly subscription fee to receive all updates and service packs for as long as you own the machine. Naturally, these predictions muddy up the definitions of secondary and tertiary storage. Welcome to the evolving world of technology.
Biographical note: Many students, especially older ones, are apprehensive about making a career change into such a fast- changing and mentally challenging field. This author is a career changer who did not make the move until he was in his forties. Consulting a friend about this ridiculous notion of moving from a profitable healthcare sales career spanning fifteen years into information technology, he provided me with a comforting insight. He said, "Mike, stuff changes so much in this field that if you really study hard and apply what you know, you can be as much of an expert as anybody else in about two years." I make an admission that I consider myself of very average intelligence, and although I found the transition to be hard and challenging, his words were largely on point with reality. Looking back on my IT career, I realize that most of what I knew ten years ago is worthless today. What I have retained and improved on are the troubleshooting principles, methods, and tools. Those never go out of style. Additionally, prolonged exposure to terminology and experience with the technology makes learning the newer changes much easier and faster to absorb.
I share this tidbit with instructors because at some point in the class, some of your students are going to feel overwhelmed. They are taking this course because they are new to the field and need the knowledge as well as the certification. If you feel they have what it takes to keep up with change, help them feel comfortable with their chances for success.

6. RAM Types Illustrated

7. RAM Types (Continued)
SDRAM = Synchronous Dynamic Random Access Memory:
PCs made before 2000 commonly use this.
Rated by bus speed:
266Mhz bus uses PC266 SDRAM.
DDR = Double Data Rate SDRAM:
Rated by throughput speed in MBps.
PC2700 means it can deliver 2,700MBps.
DDR2 = Double Data Rate SDRAM (next-generation DDR):
Twice the speed of DDR.
PC2 prefix number designates a module as DDR2.
Rambus (RDRAM) and RIMM:
Not in common use.
Topic 6.2: Memory Modules
How do you know how much RAM you should order on a new PC?
The short answer often is: "Order as much as you can afford." However, that is not quite enough information to truly answer the question because it is possible to put more memory on a motherboard than the motherboard can use. For example, you can put 16GB of memory on many newer motherboards. However, if you are running a 32-bit operating system, you will be limited to using 3.2GB of it. What a waste! Another consideration is what you will be doing with that PC. Is it going to be limited to typing word documents on how to get your A+ certification? If that is all you want to do, all you need is enough to load the operating system and a word processing program. You could get away with 512Mb, or perhaps even less.
TIP: If I were purchasing a new system today, seeing one in action, under stress, with the Task Manager running would be something I would want to do before handing over the cash. For example, take your favorite fast-action DVD or game into the store with you and play it on a machine with the specifications you think you need. Does it hiccup when pushed? Check the Task Manager. How does the memory cache play out when pushed?
Once you decide to order a certain amount of memory, you will become aware that memory modules can be purchased in varying sizes and varying capabilities. Smaller memory modules cost less—much less. At the time of this writing, you can buy two 1GB memory modules for much less than one 2GB memory module.
Even with this information, you have another consideration. How fast is your bus? If you plan to buy a new I7-core processor, and install it into a new 1366 socket with its faster north bridge bus, it makes sense to take full advantage of the processor speed by buying memory that can handle that speed. Otherwise, it would be like buying a Lamborghini and only using it in a 25 mph speed zone. Again, you will pay more for faster memory and still more to get a large amount on one stick.
A final consideration has to do with the capability of the newer processors to utilize multiple core processing. As an example, the I7-core processor from Intel has the ability to process eight program threads simultaneously. If your memory stick can only handle one thread of data routines at a time, this will be a bottleneck for your system because it effectively reduces your expensive I7 to a Celeron processor. So, pay attention to things like dual- and triple-channel memory capability. Motherboards must be specifically designed to support these types of memory. Additionally, the multi-channel design calls for the memory to be installed in multiple identically matched memory modules. You would need two modules for dual channel and three modules for triple channel.
Again, before you spend exorbitant amounts of money, put a reality check into your checkbook. Do you really need the speed and power of more memory? Can your motherboard take advantage of it? Will it significantly improve your effectiveness or productivity? Because I only type at 30 words per minute (not nanoseconds), it is tough to justify more than enough to run a word processor, if that is all I am doing. However, when I start trying to watch movies on the Internet, type an , print a photo, and download a new copy of Unbuntu at the same time that I am running these tasks inside a virtual machine, RAM resources become critical to smooth functioning of the programs I am running.

8. Table 6-2 Know These Before Taking Exam
RAM Type
Pins
Common Type and Speed
Defining Characteristic
DRAM
30 and 172
33 or 66Mhz
Obsolete.
SDRAM
168
PC133 = 133Mhz
This original version of SDRAM is rarely used on new computers, and has given way to DDR.
DDR
184
PC3200 = 400MHz/ 3200MB/s
Double the transfers per clock cycle compared to regular SDRAM.
DDR2
240
DDR2-800 (PC ) = 800MHz/ 6400MB/s
External data bus speed (I/O bus clock) is 2x DDR SDRAM.
Rambus
184 and 232
PC800 = 1600MB/s
Not used in new computers, but you still might see existing systems using RAMBUS memory modules.
Topic 6.3 (An Instructor-Guided Lab Activity): Troubleshooting RAM Usage
Answering the Question: How Do You Know When You Do Not Have Enough RAM?
Have students access the System Properties (right-click on My Computer).
The main page displays the amount of usable RAM installed. Record this amount: _________.
Have students access the Task Manager. Click on Performance tab. Have them record the following:
Commit Charge:
Total _____________
Limit: ____________
Peak: _____________
Amount of Physical Memory:
Total: _____________ Available: ______________
What is important to know about these numbers?
The commit charge is essentially another way of saying pagefile. Explain that the pagefile is a large data address block on the hard disk. It is used for temporary RAM storage when the system runs out of physical RAM. So, the limit in commit charge is the physical memory plus the amount of pagefile space on the hard drive. Note: It is not a perfect math formula because some system files in RAM are not allowed to be sent to the pagefile.
If the total of the physical RAM is in use, the available memory will approach zero. As it approaches zero, the pagefile usage starts to kick in. Have students look at the peak memory in the commit charge. As its name indicates, this indicates a peak usage of both physical memory and pagefile memory since the last boot. This is an important indicator. It is okay for this number to be a small percentage above total physical memory. However, when this number starts to approach the total commit charge, the computer is getting precariously close to applications hanging up, delivering a blue screen, or even rebooting from processor overheating. Even before it gets close to the total commit charge, it will seem noticeably slower. For example, print jobs may take significantly longer than would seem reasonable. Modern operating systems generally deal with this problem automatically, but not always perfectly. This is why having more RAM than the "recommended" amount is almost always preferable.
In short, look for the following:
RAM amount needed or utilized by the OS and programs
Motherboard compatibility
Processor utilization

9. The following slides deal with these operational characteristics.
Memory modules are classified in various ways:
The amount of memory (in bits) found on the module.
The differences between parity and non-parity memory.
The differences between ECC and non-ECC memory.
The differences between registered and unbuffered memory.
The differences between single-sided and double-sided memory.
The following slides deal with these operational characteristics.

10. Memory Module Characteristics
Single Inline Memory Module (SIMM):
Single row of 30- or 72-edge connectors. Single refers to both sides of the module having the same pinout.
Single Inline Pin Package (SIPP):
Variation on the 30-pin SIMM.
Dual Inline Memory Module (DIMM):
168-pin, 184-pin, and 240-pin versions. Dual refers to each side of the module having a different pinout.
Small Outline DIMM (SODIMM):
A compact version of the standard DIMM module, for use in notebook computers.
Rambus RDRAM Module or RIMM
A memory module using Direct Rambus memory (RDRAM) chips.

11. Operational Characteristics
Memory module width:
8 bits = 1 byte.
Memory is sold as measured in bytes:
Megabyte
Gigabyte
Memory width refers to the 32-bit or 64-bit path:
Usually matches processor/motherboard path.
A memory module is the same as a memory “bank:”
A bank of memory is one module installed in a single memory slot.
Slots must be compatible with memory module:
72-pin slot vs or 184-pin slot.
Multiple banks usually require matched pairs of memory modules.
Topic 6.4: How Do You Know What Kind of RAM to Buy and Install?
If you are installing more RAM as a supplement, the answer is pretty simple. Go look on the current memory modules and buy as close to a duplicate as possible. Matching the speed, amount, and type (DDR, DDR2, and so on) ensures the least potential for trouble. This means that you want to be wary of being sucked into cheap memory deals just because they are cheap. Do your homework and know what you are buying.
If you are completely replacing the current memory modules, you have more flexibility; however, the safest bet is to consult your motherboard manufacturer's documentation so as to know exactly, and I mean exactly, what memory modules your motherboard will support. Again, it is nice if all your memory needs will fit on one module, but if you need two or three, it is best to buy matching modules at the same time from the same manufacturer. That way, if there is a problem, the manufacturers cannot point blame at each other, causing you to absorb the cost.
TIP: Note that most students do not understand how to buy the appropriate DDR memory. The speed of the DDR has a correlation with the motherboard bus speed. If the memory is DDR6400, we can divide that number 6400/8 =800. This means that DDR6400 is most suited for an 800Mhz front-side bus. Also, mixing two different speeds of memory causes the faster memory to slow down to slower memory speed. As with all things in this evolving field, do current research to avoid using information that causes you to pay too much for utilized resources.

12. Operational Characteristics
Parity and non-parity memory:
Error checking memory costs more.
Small performance decrease.
Two types:
Parity checking:
Use of a parity bit to compute a value that must match another value to validate a data set.
ECC (error-correcting code):
Memory that both finds and corrects errors.
Typically employed on servers.
Registered vs. unbuffered:
Buffered memory (registered):
Enables system stability when large memory banks are used.

13. Installing Memory Modules
Preinstall precaution: Importance of ESD protection:
Memory can be damaged, and the damage may not show up for weeks.
ESD strap must be attached to a ground or bare metal portion of the chassis.
Hold memory modules by the side edges without touching either the pins or the memory chips.
Check to see if the locking tabs are swiveled out to open position.
Line up module to accommodate the “notch” that ensures that the module is being inserted in the right direction.
Push module straight down into position:
A slight rocking motion from end to end helps seat stubborn modules into the slot.
Engaging the locks requires extra firmness to force the locks to close into the notches on the sides of the module.

14. Installing Memory

15. Troubleshooting Memory
Sources of problems:
Incompatible module.
Overclocking/overheating.
Incompatible metals in slots and on pins:
Causes corrosion.
Need to be cleaned periodically.
Mismatched RAM speeds:
Measured in nanoseconds.
Lower numbers mean faster access times.
Newer systems generally adjust to slowest module.

16. Determining if Cache RAM Has a Memory Problem
Cache RAM holds a copy of the information in main memory.
Errors in cache RAM can appear to be errors in system RAM.
Procedure to determine if cache RAM is the cause of a memory problem:
Disable L2 cache first.
If the memory problem goes away, determine where L2 cache is located (processor or motherboard).
If motherboard uses removable cache module, replace it.
If the motherboard uses non-removable cache chips, replace the motherboard.
If L2 cache is built into the processor, replace the processor.
If the system runs normally, the replacement is successful.
If the problem persists after replacing the component containing cache RAM, return the original component(s) to the system.
Disable L1 cache.
If the system runs normally, replace the CPU and retest.
If system runs normally after replacement, the L1 cache was faulty.

17. Troubleshooting Memory
RAM-Sizing Errors at Bootup
Note the memory count reached onscreen when the memory error is detected.
Check the motherboard documentation to see which modules must be installed first.
Change one module at a time, starting with the one you think is defective, until the error goes away.
Disable cache RAM in the BIOS setup when testing memory.

18. Preventative Maintenance for Memory
Keep the surfaces of the modules clean:
Use compressed air or a data-rated vacuum cleaner to remove dust.
Use the recommended voltage level for the memory installed if your system's BIOS setup permits voltage adjustments.
Install additional case fans over or behind the location of memory modules to pull hot air out of the system.
Keep air intake vents in the front of the system clean.
Replace any defective cooling fans.

19. What Have You Learned?
What kind of memory would be useful to verify data integrity?
How many memory modules are required for a CPU with a 64-bit bus width?
What kind of memory module is typically used in L1/L2 cache and does not require a constant refresh?
In what speed standard is memory measured?

20. Unit 6 Summary
Describe what RAM does, how it works, how it relates to the system.
Describe types of RAM available, including SDRAM, DDR, and Rambus.
Describe the features of memory modules and types of memory like ECC, EDO, registered, and unbuffered.
Demonstrate how to install SIMMs and DIMMs properly.
Describe issues with RAM due to incompatible memory speeds and types.
Describe measures to take to keep memory modules clean and protected. 20