IBM的笔记本有个隐含分区，大概占4G左右的空间，里面做了一键恢复的系统，这是IBM THINKPAD的特色。当然有些私人用户买了IBM的电脑后，自己分区很有可能把IBM的这个隐含分区给删除掉，这样一来就不能使用IBM笔记本的一键恢复的功能了。
有些客户把隐含分区删了以后就要求我们帮他们做恢复出厂。当然办法还是有的，就是要拿一台相同型号的新机器做出一套系统恢复盘然后再装入要恢复的机器就可以了，不过这样的代价太大了。还有个办法就是先把硬盘都格式化，只留1个分区，然后再把要装的系统，上好驱动就把IBM TOOLS文件夹里的APPS里的东西都装上，当然最主要的还是RNR，这个软件就是做恢复的工具，现在做出来的恢复还不是很完善，只是保存在主分区中的，并不是象出厂一样有个隐含分区的。最后再放入WINXP的安装盘，找到SUPPORT下个TOOLS下做一下WINDOWS的封装就完成了。
不过就是有个遗憾就是做不出隐含分区，最好有时间有条件可以彻底研究下！
--打造IBM一键恢复
[1-4] 打造F11一键恢复
打造F11一键恢复
打造F11一键恢复系统
Sample Text以下内容是我浏览一个神舟电脑论坛的时候看到的，虽然神舟电脑确实的垃圾，但我感觉这篇帖子还是非常实用的，给那些懒人预备的。如果按以下方法可行的话就可以将原有的隐藏分区改为1G，这样就可以做一个纯净windows xp-sp2的镜象，而且也可以使其他牌子的本本具有同样F11一键恢复功能。已经有人在神舟的垃圾本上测试通过。
对于电脑用户来说，最头疼的问题莫过于系统崩溃后重装系统。虽然现在有形形色色的各种系统恢复工具，如品牌机自带的的系统恢复盘等等，但是都存在一个缺点，需要启动盘启动。蓝巨人IBM的F11功能倒是不错，无须启动盘。系统崩溃按下F11就自动恢复了，可惜为了这F11叫我等穷人去买IBM有点不太现实，难道我们就没办法了吗？不，功夫不负有心人，笔者经过参考网上文章，终于使自己的神舟优雅M153D笔记本用上了F11一键恢复功能。
IBM F11一键恢复原理：
IBM F11系统恢复的工作原理，他是在一个硬盘上有2个主分区，备份恢复分区默认为隐藏。当系崩溃按F11恢复时，隐藏的备份恢复分区自动设置为可见的活动分区，启动电脑后执行系统恢复。但是此系统存在一个缺陷，首先只有IBM用户才能享有，其次，恢复速度慢。
接下去笔者将自己利用IBM的系统恢复工具打造F11一键恢复系统过程介绍给大家，如有不足之处请各位批评指正。
准备阶段：
需要工具软件：d2dfdzip.exe(IBM的F11系统恢复工具，可在IBM官方网站下载)
PowerQuest PartitionMagic 8.0
GHOST 7.0 （8.0）
一 采用GHOST软件做好系统镜像文件
笔者在此就不多述，因为这个文件用于以后的系统恢复，所以笔者建议最好是重新安装操作系统，装好必须的应用软件，免的以后每次恢复得重新安装。
二 建立分区：
在WINDOWS下运行PQ8.0，建立分区。
1．在PQ中调整主分区C的大小，在其后空出2G空间用于做备份分区。
2．在主分区的剩余空间点右键－创建－弹出创建分区菜单，选择创建为主分区分区格式为FAT32,卷标为IBM_SERVICE。
3．然后点应用，系统重新启动后，卷标为IBM_SERVER，大小为2G的FAT32备份分区就创建完毕了。但是启动后发现我们I盘并没有出现，为什么？因为现在硬盘上有两个主分区，新建的分区隐藏了。我们再进入PQ，在新建的分区上点右键－高级－显现分区。
重启之后我们就可以看到我们新建的备份分区了。
注意：新建立的备份分区必须在主分区C的后面，假如建在主分区的前面或者建在扩展分区上都将导致F11功能无法使用。分区域格式必须为FAT32,否则DOS下的GHOST软件将无法正常运行。卷标必须为IBM_SERVICE,否则IBM 的F11恢复软件将不能工作。
三 备份分区的设置
1．使备份分区具有启动功能。因为当系统崩溃后，要使用备份分区来启动电脑，所以必须要在备份分区根目录下存在DOS的基本启动文件。可以在98系统下制作启动盘，或者用第二个办法，现在的D版光盘都带有启动功能，利用光盘启动电脑，自动默认盘符为A:,将A盘中的所有文件拷贝到硬盘上的备份分区中。(DOS三个基本启动文件COMMAND.COM MS-DOS.SYS IO.SYS)
2．拷贝GHOST软件和第一步做好的GHOST镜像文件到备份分区根目录。
3．用记事本创建Config.sys文件
Device = c:\\himen.sys
保存为config.sys
4．创建自动批处理文件AUTOEXEC.BAT
Ghost.exe -clone,mode=pload,src=c:\\winxp.gh1,dst=1:1 -sure –rb
注意：请不要修改此处的镜像文件路径：C:\\winxp.gho，笔者在第一次时将路径改为I，结果无法执行。原因是当备份分区激活启动时，原系统分区隐藏，备份分区成了C盘。
Dst=1:1是恢复文件到第一个硬盘的第一个分区。
四F11功能安装
1．将从IBM官方网站下载的d2dfdzip文件解压缩到C盘根目录，并修改其中的AUTOEXEC.BAT文件
a:\\bmgr.exe /Fboot.bin /Mbmgr%CC%.scr /s
a:\\bmgr.exe /Fboot.bin /Mbmgr%CC%.scr /s
将此两行的路径由a:设置成c:,因为我们的笔记没软驱是直接在C盘执行。
2．拷贝DOS的分区软件FDISK.EXE到C盘根目录，因为F11功能需要写硬盘引导记录。在刚才制作的启动盘中有。
3．用启动盘启动计算机到DOS下，转换盘符到C:,输入autoexec.bat
显示一个文件拷贝，按CTRL+ALT+DEL重新启动电脑。
重新启动后是不是发现我们的F11功能已经出现，我们的备份分区也自动隐藏了。
总结：
至此，我们的F11一键恢复系统就打造完成了。以后假如发生系统崩溃只要在重启时按一下F11,就自动恢复了。笔者的神舟幽雅M153D笔记本三用三星硬盘恢复速度达到650M,三分钟就拥有一个新的系统了。
此方法不仅可以在笔记本上使用，我们的台式机也同样适用。有了F11,我们再也不用怕系统崩溃拉 。
本文出自这里
Sunday, April 6, 2008
Recovery Sony AVIO VGN-FJ77C
My friend laptop Sony AVIO is down. The senario is: after AVIO logo appearing, the cursor will be dead.
I am trying to recover the default factory installation.
Search this link When the Vaio logo appears press F10
I press F10, and I utility come out and start running.
But I met a blue screen such as : dxg.sys issue, hardware,software causes this problem.
PAGE_FAULT_IN_NONPAGED_AREA ERROR:
Explanation:
This Stop message occurs when requested data is not found in memory. The system generates a fault, which normally indicates that the system looks for data in the paging file. In this circumstance, however, the missing data is identified as being located within an area of memory that cannot be paged out to disk. The system faults, but cannot find, the data and is unable to recover. Faulty hardware, a buggy system service, antivirus software, and a corrupted NTFS volume can all generate this type of error.
User Action:
This Stop message usually occurs after the installation of faulty hardware or in the event of failure of installed hardware (usually related to defective RAM, either main memory, L2 RAM cache, or video RAM). If hardware has been added to the system recently, remove it to see if the error recurs. If existing hardware has failed, remove or replace the faulty component. Run hardware diagnostics supplied by the system manufacturer. For details on these procedures, see the owners manual for your computer. Another cause of this Stop message is the installation of a buggy system service. Disable the service and determine if this resolves the error. If so, contact the manufacturer of the system service about a possible update. If the error occurs during system startup, restart your computer, and press F8 at the character-mode menu that displays the operating system choices. At the resulting Windows 2000 Advanced Options menu, choose the Last Known Good Configuration option. This option is most effective when only one driver or service is added at a time. Antivirus software can also trigger this Stop message. Disable the program and determine if this resolves the error. If it does, contact the manufacturer of the program about a possible update. A corrupted NTFS volume can also generate this Stop message. Run Chkdsk /f /r to detect and repair disk errors. Restart the system before the disk scan begins on a system partition. If the hard disk is SCSI, check for problems between the SCSI controller and the disk. Finally, check the System Log in Event Viewer for additional error messages that might help pinpoint the device or driver causing the error. Disabling memory caching of the BIOS might also resolve it. For more troubleshooting information about this Stop message, refer to the Microsoft Knowledge Base at http://support.microsoft.com/support.
I am trying to recover the default factory installation.
Search this link When the Vaio logo appears press F10
I press F10, and I utility come out and start running.
But I met a blue screen such as : dxg.sys issue, hardware,software causes this problem.
PAGE_FAULT_IN_NONPAGED_AREA ERROR:
Explanation:
This Stop message occurs when requested data is not found in memory. The system generates a fault, which normally indicates that the system looks for data in the paging file. In this circumstance, however, the missing data is identified as being located within an area of memory that cannot be paged out to disk. The system faults, but cannot find, the data and is unable to recover. Faulty hardware, a buggy system service, antivirus software, and a corrupted NTFS volume can all generate this type of error.
User Action:
This Stop message usually occurs after the installation of faulty hardware or in the event of failure of installed hardware (usually related to defective RAM, either main memory, L2 RAM cache, or video RAM). If hardware has been added to the system recently, remove it to see if the error recurs. If existing hardware has failed, remove or replace the faulty component. Run hardware diagnostics supplied by the system manufacturer. For details on these procedures, see the owners manual for your computer. Another cause of this Stop message is the installation of a buggy system service. Disable the service and determine if this resolves the error. If so, contact the manufacturer of the system service about a possible update. If the error occurs during system startup, restart your computer, and press F8 at the character-mode menu that displays the operating system choices. At the resulting Windows 2000 Advanced Options menu, choose the Last Known Good Configuration option. This option is most effective when only one driver or service is added at a time. Antivirus software can also trigger this Stop message. Disable the program and determine if this resolves the error. If it does, contact the manufacturer of the program about a possible update. A corrupted NTFS volume can also generate this Stop message. Run Chkdsk /f /r to detect and repair disk errors. Restart the system before the disk scan begins on a system partition. If the hard disk is SCSI, check for problems between the SCSI controller and the disk. Finally, check the System Log in Event Viewer for additional error messages that might help pinpoint the device or driver causing the error. Disabling memory caching of the BIOS might also resolve it. For more troubleshooting information about this Stop message, refer to the Microsoft Knowledge Base at http://support.microsoft.com/support.
Wednesday, April 2, 2008
Identifying PC133 Memory Modules!
PC133 Introduction - Basic
Hi My friend,
I got new knowledge on PC133 memory. It is great to know them. Let me share with you.
What you should know..
Before we show you how to distinguish PC133 memory from all others, some background information might be appropriate. Elsewhere in our Performance Center we have discussed How to Visually Identify Memory Types, How to Verify PC100 Compliant Memory and what the PC100 Standard is all about.
With the ever present push for performance, processors, motherboard buses and other computer system components have seen dramatic speed increases. With that, memory technology has been making some leaps of its own. In 1995 memory speed jumped from 33MHz to 66MHz with the release of EDO memory. In 1997 we saw SDRAM speeds jump to 66MHz with the release of PC66 SDRAM, and shortly thereafter the engineers moved the speed lever again, this time to 100MHz with the release of PC100 in 1998. Engineers, though, were not ready to quit just yet, as barely a year later, in 1999, we saw the release of PC133 SDRAM, with memory speeds running at 133MHz and higher.
During 1999 and 2000 we saw dramatic changes in the engineering and development of memory technology with the release of RDRAM (Rambus®) memory running at 800MHz and DDR SDRAM running at 266MHz. On the surface it doesn't seem to make much sense to develop DDR SDRAM at 266MHz when you have Rambus® running at 800MHz, but in truth, they are direct competitors when it comes to memory speed, as DDR SDRAM is an entirely new design that reduces DRAM latencies and substantially increases memory bandwidth. Follow these links for a brief Introduction to DDR SDRAM, as well as a Comparison of DDR SDRAM and Rambus ® memory.
In spite of these new advances though, PC100 and PC133 SDRAM, is not dead by a long shot. Now that you have some background, let's discuss briefly what PC133 SDRAM is, and how to correctly identify it when you purchase it.
As was the case in our review of PC100, PC133 SDRAM must be manufactured to meet the specific standards set by Intel. And like PC100, beware, as there are unscrupulous suppliers selling PC133 modules that do not meet the Standard and this is reflected in their performance. If you have Adobe Acrobat installed, click this link to review Intel's PC133 Validation Specifications for PC 133 Modules.
PC133 SDRAM
Synchronous dynamic random access memory (SDRAM) delivers bursts of data at very high speeds using an interface that is synchronized to the CPU clock. SDRAM emerged in 1996, and represented a big step forward from EDO technology. When manufactured, PC133 SDRAM, must meet Intel's requirements (the PC133 Standard) for use with motherboards having a 133MHz FSB (front side bus). PC133 compliant SDRAM is almost always a requirement in Pentium III, AMD Athlon and Power Mac G4 based systems. This link will provide you with a review about Memory Speed.
While PC133 SDRAM can be used with motherboards having a 100MHz front side bus, your memory will only operate as fast as the slowest "link" in your system, in this case the motherboards 100MHz front side bus. As an example, if you were to install a PC133 module in a system with a 100MHz FSB, or in a system already containing a 100MHz module, the PC133 module will operate only at 100MHz. PC133 SDRAM is available only in the form of a 168-pin DIMM (as it pertains to personal computers).
Lets review what makes a PC133 module different from its predecessors. Keep in mind, that when suppliers sell memory modules, they often provide technical specifications and descriptions of the modules performance. If your supplier isn't providing this information, beware! Below are some of the terms you may see in those descriptions. You will also find additional definitions in our Memory Glossary.
Clocks and Latency (CL=2 - CL=3)
"CL=2" (also written as "CL2" or "CAS=2") and "CL=3" (also written as "CL2" and "CAS=2") refers to a module's CAS latency. CAS latency is the amount of time it takes for your memory to respond to a command. It only affects the initial burst of data. Once data starts flowing, latency is no longer significant. Following this link will take you to a more in depth discussion of Memory Latencies.
Latency is measured in terms of clock cycles. A CL=2 chip requires two clock cycles to respond, and a CL=3 chip requires three clock cycles, therefore CL=2 chips complete the initial data access a little more quickly than CL=3 chips. Keep in mind though, a clock cycle for a system with a 100MHz front side bus is only 10 nanoseconds (10 billionths of a second), therefore don't be too surprised if you're unable to tell the difference between a CL=2 and a CL=3 chip. While most systems will accept memory modules having either a CL=2 or CL=3 chip, there are some systems that require one or the other. Generally your motherboard's manufacturer will advise you of their requirements, however should you not be able to determine this, just let us know and we will help you select the right module.
As an example, a few systems built by Dell and Gateway require a particular type of CL=2 memory known as 2-clock memory. While this memory technology is no longer used in modern systems, Crucial, Samsung and a few other manufacturers continue to offer this unique type of module for upgrade customers. If you need 2-clock memory for your system, just let us know the make and model of your computer and we will provide you with the correct module.
How does a PC determine what CL value to use?
During the startup (Boot) process, the motherboards BIOS software reads the value for CL (CAS Latency), tRCD and tRP that is programmed into the Serial Presence Detect (SPD) EEPROM on the SDRAM DIMM memory module. The memory controller will then issue SDRAM commands to meet the memory device requirements.
Let's look at the differences between PC133 and other SDRAM Memory.
As you may have noted above, the PC133 SDRAM module was designed to improve the memory bandwidth of the personal computer from 100Mhz to 133Mhz. Typically, the 133 MHz SDRAM chip has a speed rating of 7.5 nanoseconds (7.5 billionths of a second) when running on a motherboard with a 133 MHz Front Side Bus.
This table, courtesy of Micron, shows the specification and speed differences between the most recent forms of SDRAM, PC66, PC100 and PC133.
PC66 - PC100 - PC133 SDRAM COMPARISON CHART
Module
Type
SDRAM
SPEED
TIME (ns)
CLOCKS
BUS SPEED
tWR
tRP
tWR
tRP
MHz
ns
PC66
-10 10 30 1 *1
33 30
-10 10-15 30 2 2 66 15
PC100
-8A/B 15 24 2 3 100 10
-8C 15 20 2 2 100 10
-8E 15 20 2 2 100 10
PC133
-75 15 20 2 3 133 7.5
-7E 14 15 2 2 133 7.5
*As a general rule, personal computers use 2 clock memory
As you can see from the above table, memory speeds have accelerated from PC66 at 33MHz and 30 nanoseconds (30 billionths of a second) to PC133 at 133MHz and 7.5 nanoseconds (7.5 billionths of a second). We know what you're thinking, how can you really tell the difference between 30 billionths of a second and 7.5 billionths of a second? Simply put, you can't, but your computer can, and it makes a difference!
Dispelling the confusion between Front Side Bus Frequency and CPU Frequency
The Front Side Bus (FSB), the memory bus between the Processor and the Memory module, is the main information or data highway in the PC system. The faster the bus runs, the faster data can transfer between the processor and memory.
The speed of the FSB is not the same as processor speed (yet), but technology is quickly changing this, and very shortly you will see the processor and FSB running at the same speed. If you have a 600MHz Pentium processor with a 100MHz Front Side Bus, the information flowing within the processor will run at 600MHz, whenever the data is transferred outside the processor, the data will flow only at 100MHz. At present, one of the overall limiting factors in PC systems today is the bus speed. While you may have a processor running at 800 or 1,000 MHz, and memory capable of running at 800 MHZ, data transfers will never run faster than the Front Side Bus speed. Once developers conquer this limitation, personal computers will operate at speeds previously unheard of.
Now it's time to get down to the nitty gritty!
Most 133MHz SDRAM chips are actually designed to run at 150MHz and faster. These chips are often referred to as "-7.5" (7.5 nanosecond parts). You can identify the chips by reading “-7” in the last two digits on the chip part numbering found on most PC133 memory modules. The “-7” refers to the minimum operating clock cycle of the device.
How to determine the frequency of the module?
Again, the simplest way to determine if the module is PC66, PC100 or PC133, is by simply reading the last digit or two of the part number on the actual chip. Here are two examples, a PC100 module from Micron and a PC100 chip from Samsung.
As you can see from the red arrow, this Micron chip has a "-8" designation that identifies it as 100MHz bus and 10 nanosecond. As noted earlier, had this chip had a "-7" or "-7.5" designator, that would indicate it was a PC133 chip, and had it been "-10" it would be PC66. Even knowing this, should you be uncertain of the modules specifications, Micron makes it easy to verify them by providing a part number cross reference, which you can see by clicking this link.
Now let's look at the Samsung chip.
Although the above chip is made by Samsung, directly identifying the speed without a reference sheet that explains the codes is a little more difficult. The last pair of digits in the part number, “G8”, indicate that it is a 125Mhz device, or a PC100 memory chip. Recently, Samsung changed their part number scheme, and permanently removed their old reference sheets. The following links will provide you with Samsung's new SDRAM part number reference.
Briefly, here is what the part number represents. We have broken it down based upon Samsung's reference sheets:
1 2 3 4 5 6 7 8 9 10 11 12 13
KM 4 8 S 8 0 3 0 B T - G 8
1 KM indicates that the chip is a Samsung part.
2 4 = Indicates that this a DRAM part
3 8 = Indicates the chip organization (x8)
4 S = Indicates the ship is specifically SDRAM
5 8 = Indicates the density of this chip as 8M
6 0 = Indicates the Refresh, in this case 4K
7 3 = Indicates the number of chip banks (4 banks)
8 0 = Indicates type and mount of voltage (LVTTL (3.3V)
9 B = Indicates the Revision number (3rd generation)
10 T = Packaging type. In this case TSOP II (400mil)
11 - No value
12 G = Indicates Power - Auto & Self-Refresh (3.3V)
13 8 = Indicates Min. cycle time 8ns(125MHz@CL=3)
Before we close this subject, we feel it is necessary to have you understand that all too often, consumers do not read the entire part number when they inspect the memory modules they receive. All of the numbers and letters making up the part number of a memory module are important in correctly identifying its specifications. Here's a data sheet from Samsung.
Normally the five red arrows that you see above would not be present when you review a data sheet. If you look closely at each of the five part numbers, you will see that the only difference are the last two digits. Those two digits alone determine whether the module is PC66, PC100, PC125 or PC133 as you can see by the chart.
Kingston Technology uses a similar method to indicate the parameters and specifications of their memory modules, and this link will take you to the Kingston Technology Reference.
As long as your memory modules, and the chips on them, are manufactured by a major supplier, such as Micron/Crucial, Kingston, Samsung, IBM, Hyundai, NEC, Toshiba, Hitachi, you can usually rest assured that you are receiving quality memory. Just be careful to make sure that you purchase your modules from reputable resellers. It is also important to note that many manufacturers have both premium as well as inexpensive versions of their memory products. You get what you pay for! Also important, as mentioned elsewhere on this Website, some modules arriving from certain Asian countries have been re-marked to change the part information. Beware!
The Bottom Line, what makes a good PC133 Module?
When Intel introduced the PC100 SDRAM specification, a list of standards and specifications were compiled to insure the uniformity of manufacture of memory chips and modules. These standards and specifications had to be met by both semiconductor and module manufacturers to not only insure uniformity of fabrication, but also to insure the accuracy of data handling at higher DRAM speeds. As SDRAM speed changed, increasing from 100MHz to 133MHz (and above), the specifications for the new SDRAM changed as well. The PC133 Intel/JEDEC Standard still includes the following:
Minimum and maximum trace lengths for all signals on the module
Precise specifications for trace width and spacing
Detailed specifications for the distances between each circuit board layer
Only 6 layer PCB's with unbroken power and ground planes
Well balanced clock trace lengths, as well as routing, loading, and termination requirements
Series termination resistors on all data lines
Detailed SDRAM component specification
Detailed EEPROM SPD programming specification
Special Label/Marking Requirements
Electro Magnetic Interference (EMI) Suppression
Gold plated printed circuit boards
The Jedec/Intel specification goes to great length to detail each of the above issues, dictating what the manufacturer must do in order to meet the standard. In theory, as long as manufacturers meet or exceed these specifications, all memory modules produced by all manufacturers will be identical and rarely produce problems. This common uniformity standard was designed to insure that all SDRAM memory module should be created equal and there shouldn’t be any major variations between any two module made by different companies. Unfortunately though, in the real world, you will find that SDRAM modules with identical SDRAM chips, can sometimes reach entirely different frequencies for no other reason than differences in the manufacturing of their printed circuit boards and the trace layouts on them. For this reason alone, always try and purchase all of the memory you need at the same time and from the same supplier.
Conclusion
Simply put, usually the last digit or two of the part number on the memory chip will indicate the memory type. PC66 memory chips will be "12", PC100 will be either "8" or "10", and PC133 will be either "-65", "-7" or "-75", representing 6.5, 7 and 7.5 nanoseconds respectively.
Every day we field questions from people who want to upgrade their PC's by adding more memory, and one of the most Frequently Asked Questions involves that of compatibility. We constantly field questions as to whether PC100 and PC133 memory can be mixed on the same motherboard, or whether replacing PC66 memory with PC133 will make someone's system faster.
While there are many cases where PC100 modules, and even the older PC66 SDRAM modules, have worked together on the same motherboard at 133MHz bus speeds, however those situations are extremely rare and ill advised. In an emergency, anything is worth a try. Just remember that the purpose of your computer is that of dealing with data, regardless of whether you're dealing with games or physics calculations. It is pointless to mix memory types when the end result will almost certainly result in corrupted data.
When purchasing memory for a new system, make it a point to purchase all of the memory you need at the same time from the same supplier. If you are upgrading, try and match as closely as possible the memory modules you already have.
If you would like to review more about memory related issues, you may want to follow these links:
Memory, Evolution or a Revolution?
How Memory Speeds Are Determined
How to Identifying Different Memory Types
Does your memory meet the Standard?
Frequently Asked Questions About Memory
Troubleshooting Memory Problems
Megabyte (MB) vs. Megabit (Mb)
Memory Trends in 2001
Hi My friend,
I got new knowledge on PC133 memory. It is great to know them. Let me share with you.
What you should know..
Before we show you how to distinguish PC133 memory from all others, some background information might be appropriate. Elsewhere in our Performance Center we have discussed How to Visually Identify Memory Types, How to Verify PC100 Compliant Memory and what the PC100 Standard is all about.
With the ever present push for performance, processors, motherboard buses and other computer system components have seen dramatic speed increases. With that, memory technology has been making some leaps of its own. In 1995 memory speed jumped from 33MHz to 66MHz with the release of EDO memory. In 1997 we saw SDRAM speeds jump to 66MHz with the release of PC66 SDRAM, and shortly thereafter the engineers moved the speed lever again, this time to 100MHz with the release of PC100 in 1998. Engineers, though, were not ready to quit just yet, as barely a year later, in 1999, we saw the release of PC133 SDRAM, with memory speeds running at 133MHz and higher.
During 1999 and 2000 we saw dramatic changes in the engineering and development of memory technology with the release of RDRAM (Rambus®) memory running at 800MHz and DDR SDRAM running at 266MHz. On the surface it doesn't seem to make much sense to develop DDR SDRAM at 266MHz when you have Rambus® running at 800MHz, but in truth, they are direct competitors when it comes to memory speed, as DDR SDRAM is an entirely new design that reduces DRAM latencies and substantially increases memory bandwidth. Follow these links for a brief Introduction to DDR SDRAM, as well as a Comparison of DDR SDRAM and Rambus ® memory.
In spite of these new advances though, PC100 and PC133 SDRAM, is not dead by a long shot. Now that you have some background, let's discuss briefly what PC133 SDRAM is, and how to correctly identify it when you purchase it.
As was the case in our review of PC100, PC133 SDRAM must be manufactured to meet the specific standards set by Intel. And like PC100, beware, as there are unscrupulous suppliers selling PC133 modules that do not meet the Standard and this is reflected in their performance. If you have Adobe Acrobat installed, click this link to review Intel's PC133 Validation Specifications for PC 133 Modules.
PC133 SDRAM
Synchronous dynamic random access memory (SDRAM) delivers bursts of data at very high speeds using an interface that is synchronized to the CPU clock. SDRAM emerged in 1996, and represented a big step forward from EDO technology. When manufactured, PC133 SDRAM, must meet Intel's requirements (the PC133 Standard) for use with motherboards having a 133MHz FSB (front side bus). PC133 compliant SDRAM is almost always a requirement in Pentium III, AMD Athlon and Power Mac G4 based systems. This link will provide you with a review about Memory Speed.
While PC133 SDRAM can be used with motherboards having a 100MHz front side bus, your memory will only operate as fast as the slowest "link" in your system, in this case the motherboards 100MHz front side bus. As an example, if you were to install a PC133 module in a system with a 100MHz FSB, or in a system already containing a 100MHz module, the PC133 module will operate only at 100MHz. PC133 SDRAM is available only in the form of a 168-pin DIMM (as it pertains to personal computers).
Lets review what makes a PC133 module different from its predecessors. Keep in mind, that when suppliers sell memory modules, they often provide technical specifications and descriptions of the modules performance. If your supplier isn't providing this information, beware! Below are some of the terms you may see in those descriptions. You will also find additional definitions in our Memory Glossary.
Clocks and Latency (CL=2 - CL=3)
"CL=2" (also written as "CL2" or "CAS=2") and "CL=3" (also written as "CL2" and "CAS=2") refers to a module's CAS latency. CAS latency is the amount of time it takes for your memory to respond to a command. It only affects the initial burst of data. Once data starts flowing, latency is no longer significant. Following this link will take you to a more in depth discussion of Memory Latencies.
Latency is measured in terms of clock cycles. A CL=2 chip requires two clock cycles to respond, and a CL=3 chip requires three clock cycles, therefore CL=2 chips complete the initial data access a little more quickly than CL=3 chips. Keep in mind though, a clock cycle for a system with a 100MHz front side bus is only 10 nanoseconds (10 billionths of a second), therefore don't be too surprised if you're unable to tell the difference between a CL=2 and a CL=3 chip. While most systems will accept memory modules having either a CL=2 or CL=3 chip, there are some systems that require one or the other. Generally your motherboard's manufacturer will advise you of their requirements, however should you not be able to determine this, just let us know and we will help you select the right module.
As an example, a few systems built by Dell and Gateway require a particular type of CL=2 memory known as 2-clock memory. While this memory technology is no longer used in modern systems, Crucial, Samsung and a few other manufacturers continue to offer this unique type of module for upgrade customers. If you need 2-clock memory for your system, just let us know the make and model of your computer and we will provide you with the correct module.
How does a PC determine what CL value to use?
During the startup (Boot) process, the motherboards BIOS software reads the value for CL (CAS Latency), tRCD and tRP that is programmed into the Serial Presence Detect (SPD) EEPROM on the SDRAM DIMM memory module. The memory controller will then issue SDRAM commands to meet the memory device requirements.
Let's look at the differences between PC133 and other SDRAM Memory.
As you may have noted above, the PC133 SDRAM module was designed to improve the memory bandwidth of the personal computer from 100Mhz to 133Mhz. Typically, the 133 MHz SDRAM chip has a speed rating of 7.5 nanoseconds (7.5 billionths of a second) when running on a motherboard with a 133 MHz Front Side Bus.
This table, courtesy of Micron, shows the specification and speed differences between the most recent forms of SDRAM, PC66, PC100 and PC133.
PC66 - PC100 - PC133 SDRAM COMPARISON CHART
Module
Type
SDRAM
SPEED
TIME (ns)
CLOCKS
BUS SPEED
tWR
tRP
tWR
tRP
MHz
ns
PC66
-10 10 30 1 *1
33 30
-10 10-15 30 2 2 66 15
PC100
-8A/B 15 24 2 3 100 10
-8C 15 20 2 2 100 10
-8E 15 20 2 2 100 10
PC133
-75 15 20 2 3 133 7.5
-7E 14 15 2 2 133 7.5
*As a general rule, personal computers use 2 clock memory
As you can see from the above table, memory speeds have accelerated from PC66 at 33MHz and 30 nanoseconds (30 billionths of a second) to PC133 at 133MHz and 7.5 nanoseconds (7.5 billionths of a second). We know what you're thinking, how can you really tell the difference between 30 billionths of a second and 7.5 billionths of a second? Simply put, you can't, but your computer can, and it makes a difference!
Dispelling the confusion between Front Side Bus Frequency and CPU Frequency
The Front Side Bus (FSB), the memory bus between the Processor and the Memory module, is the main information or data highway in the PC system. The faster the bus runs, the faster data can transfer between the processor and memory.
The speed of the FSB is not the same as processor speed (yet), but technology is quickly changing this, and very shortly you will see the processor and FSB running at the same speed. If you have a 600MHz Pentium processor with a 100MHz Front Side Bus, the information flowing within the processor will run at 600MHz, whenever the data is transferred outside the processor, the data will flow only at 100MHz. At present, one of the overall limiting factors in PC systems today is the bus speed. While you may have a processor running at 800 or 1,000 MHz, and memory capable of running at 800 MHZ, data transfers will never run faster than the Front Side Bus speed. Once developers conquer this limitation, personal computers will operate at speeds previously unheard of.
Now it's time to get down to the nitty gritty!
Most 133MHz SDRAM chips are actually designed to run at 150MHz and faster. These chips are often referred to as "-7.5" (7.5 nanosecond parts). You can identify the chips by reading “-7” in the last two digits on the chip part numbering found on most PC133 memory modules. The “-7” refers to the minimum operating clock cycle of the device.
How to determine the frequency of the module?
Again, the simplest way to determine if the module is PC66, PC100 or PC133, is by simply reading the last digit or two of the part number on the actual chip. Here are two examples, a PC100 module from Micron and a PC100 chip from Samsung.
As you can see from the red arrow, this Micron chip has a "-8" designation that identifies it as 100MHz bus and 10 nanosecond. As noted earlier, had this chip had a "-7" or "-7.5" designator, that would indicate it was a PC133 chip, and had it been "-10" it would be PC66. Even knowing this, should you be uncertain of the modules specifications, Micron makes it easy to verify them by providing a part number cross reference, which you can see by clicking this link.
Now let's look at the Samsung chip.
Although the above chip is made by Samsung, directly identifying the speed without a reference sheet that explains the codes is a little more difficult. The last pair of digits in the part number, “G8”, indicate that it is a 125Mhz device, or a PC100 memory chip. Recently, Samsung changed their part number scheme, and permanently removed their old reference sheets. The following links will provide you with Samsung's new SDRAM part number reference.
Briefly, here is what the part number represents. We have broken it down based upon Samsung's reference sheets:
1 2 3 4 5 6 7 8 9 10 11 12 13
KM 4 8 S 8 0 3 0 B T - G 8
1 KM indicates that the chip is a Samsung part.
2 4 = Indicates that this a DRAM part
3 8 = Indicates the chip organization (x8)
4 S = Indicates the ship is specifically SDRAM
5 8 = Indicates the density of this chip as 8M
6 0 = Indicates the Refresh, in this case 4K
7 3 = Indicates the number of chip banks (4 banks)
8 0 = Indicates type and mount of voltage (LVTTL (3.3V)
9 B = Indicates the Revision number (3rd generation)
10 T = Packaging type. In this case TSOP II (400mil)
11 - No value
12 G = Indicates Power - Auto & Self-Refresh (3.3V)
13 8 = Indicates Min. cycle time 8ns(125MHz@CL=3)
Before we close this subject, we feel it is necessary to have you understand that all too often, consumers do not read the entire part number when they inspect the memory modules they receive. All of the numbers and letters making up the part number of a memory module are important in correctly identifying its specifications. Here's a data sheet from Samsung.
Normally the five red arrows that you see above would not be present when you review a data sheet. If you look closely at each of the five part numbers, you will see that the only difference are the last two digits. Those two digits alone determine whether the module is PC66, PC100, PC125 or PC133 as you can see by the chart.
Kingston Technology uses a similar method to indicate the parameters and specifications of their memory modules, and this link will take you to the Kingston Technology Reference.
As long as your memory modules, and the chips on them, are manufactured by a major supplier, such as Micron/Crucial, Kingston, Samsung, IBM, Hyundai, NEC, Toshiba, Hitachi, you can usually rest assured that you are receiving quality memory. Just be careful to make sure that you purchase your modules from reputable resellers. It is also important to note that many manufacturers have both premium as well as inexpensive versions of their memory products. You get what you pay for! Also important, as mentioned elsewhere on this Website, some modules arriving from certain Asian countries have been re-marked to change the part information. Beware!
The Bottom Line, what makes a good PC133 Module?
When Intel introduced the PC100 SDRAM specification, a list of standards and specifications were compiled to insure the uniformity of manufacture of memory chips and modules. These standards and specifications had to be met by both semiconductor and module manufacturers to not only insure uniformity of fabrication, but also to insure the accuracy of data handling at higher DRAM speeds. As SDRAM speed changed, increasing from 100MHz to 133MHz (and above), the specifications for the new SDRAM changed as well. The PC133 Intel/JEDEC Standard still includes the following:
Minimum and maximum trace lengths for all signals on the module
Precise specifications for trace width and spacing
Detailed specifications for the distances between each circuit board layer
Only 6 layer PCB's with unbroken power and ground planes
Well balanced clock trace lengths, as well as routing, loading, and termination requirements
Series termination resistors on all data lines
Detailed SDRAM component specification
Detailed EEPROM SPD programming specification
Special Label/Marking Requirements
Electro Magnetic Interference (EMI) Suppression
Gold plated printed circuit boards
The Jedec/Intel specification goes to great length to detail each of the above issues, dictating what the manufacturer must do in order to meet the standard. In theory, as long as manufacturers meet or exceed these specifications, all memory modules produced by all manufacturers will be identical and rarely produce problems. This common uniformity standard was designed to insure that all SDRAM memory module should be created equal and there shouldn’t be any major variations between any two module made by different companies. Unfortunately though, in the real world, you will find that SDRAM modules with identical SDRAM chips, can sometimes reach entirely different frequencies for no other reason than differences in the manufacturing of their printed circuit boards and the trace layouts on them. For this reason alone, always try and purchase all of the memory you need at the same time and from the same supplier.
Conclusion
Simply put, usually the last digit or two of the part number on the memory chip will indicate the memory type. PC66 memory chips will be "12", PC100 will be either "8" or "10", and PC133 will be either "-65", "-7" or "-75", representing 6.5, 7 and 7.5 nanoseconds respectively.
Every day we field questions from people who want to upgrade their PC's by adding more memory, and one of the most Frequently Asked Questions involves that of compatibility. We constantly field questions as to whether PC100 and PC133 memory can be mixed on the same motherboard, or whether replacing PC66 memory with PC133 will make someone's system faster.
While there are many cases where PC100 modules, and even the older PC66 SDRAM modules, have worked together on the same motherboard at 133MHz bus speeds, however those situations are extremely rare and ill advised. In an emergency, anything is worth a try. Just remember that the purpose of your computer is that of dealing with data, regardless of whether you're dealing with games or physics calculations. It is pointless to mix memory types when the end result will almost certainly result in corrupted data.
When purchasing memory for a new system, make it a point to purchase all of the memory you need at the same time from the same supplier. If you are upgrading, try and match as closely as possible the memory modules you already have.
If you would like to review more about memory related issues, you may want to follow these links:
Memory, Evolution or a Revolution?
How Memory Speeds Are Determined
How to Identifying Different Memory Types
Does your memory meet the Standard?
Frequently Asked Questions About Memory
Troubleshooting Memory Problems
Megabyte (MB) vs. Megabit (Mb)
Memory Trends in 2001
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