Processor Identification and ReplacementProcessor Identification and ReplacementQ. Are the Cyrix 6x86 and the IBM 6x86 the same chip?
A. The basis of the Cyrix/IBM relationship is that Cyrix provides the design and IBM provides the CMOS technology and fabricates the wafers. Cyrix gets roughly half the wafers and IBM gets the other half, but Cyrix owns the design. The idea of the partnership is that IBM and Cyrix each do what they do best and share in the proceeds. Cyrix has an excellent design team and IBM has world class fabrication facilities.
The differences between the chips are in the packaging (IBM sells wafers) and the testing of the modules. Sometimes IBM buys the same module package (the ceramic body with pins that plug into the motherboard socket) to put the chip in as Cyrix does and sometimes they don't. The next difference is how the parts are tested. IBM chips are suppose to have met additional and more stringent testing requirements than the Cyrix chips before the are given a rating and sold. This point alone may be enough of a reason for all of you overclocking types to consider IBM over Cyrix.
The IBM chip is also slightly cheaper than the Cyrix chip. Outside of these differences, the chips are exactly the same. Don't let any marketing or sales guy try to tell you differently.
Q. What are the differences between 6x86 chip revisions?
A. It is Cyrix's corporate policy not to discuss the specific details of the company's chip revisions. The only differences between 6x86 chip revisions that Cyrix will make public occur as a result of manufacturing. The first 6x86 samples and the PR120+, PR133+, and PR150+ parts were manufactured using a 0.6 micron technology. The PR166+ & PR200+ parts up to revision 2.7 were manufactured using a 0.5 micron technology. The revision 3.7 and above parts are a 10% optical shrinked design and were manufactured using a 0.44 micron technology. The revision 4.2 (6x86L) parts are a dual voltage (core 2.8v, I/O 3.3v) chip manufactured using a 0.35 micron technology. These chips have a 2.8V label written on them and will use the low voltage 6x86L setting available on some motherboards. Another technical term being used for the dual voltage setup is split-rail.
Q. What do the 6x86 revision numbers mean?
A. The number to the right of the decimal point indicates an actual design change or modification. The number to the left of the decimal point indicates the manufacturing technology used. Design changes or modifications do not necessarily mean bug fixes. A design change can occur in order to improve yields. Higher yields produce faster chips that can be sold for more money. The definition of what each design change or modification actually is is confidential information contained in errata sheets.
The revision 3.x was a 10% die shrink. We are now seeing 4.x revision parts being produced. The increase in the number to the left of the decimal occurred as a result of new manufacturing technology. We know that this is dual voltage instead of die shrink.
A. The Cyrix 6x86 revision number can be determined from a serial number on the underside of the chip. The following serial number is an example to give you an idea of what to look for: G8DC6620A. Here is the correct way to read and understand the serial number to determine what 6x86 revision you have. This information has been confirmed by a very knowledgeable source.
The Gx prefix indicates the silicon process used.
2.x's begin with G8
3.x's begin with G9
4.x's begin with GAIf your serial number starts with a G8, the following applies.
G8XX
XX can be one or two charactersG8XX6
4 is for version 2.5
5 is for version 2.6
6 is for version 2.7G8XX66
6 is for 1996
So a version 2.7 chip could read G8XX66 or G8X66G8XX6620
20 is for week 20. For example, a G8X6620 would fall into production during the 20th week of the year which is in June.Next comes the lot number which I will show as @@@@@.
So a 2.7 revision chip could read G8XX6620@@@@@ or G8X6620@@@@@If your serial number starts with a G9, the following applies.
G9XX
XX can be one or two charactersG9XXA
A is for version 3.7
B is for version 3.8G9XXA6
6 is for 1996
So a version 3.7 chip could read G9XXA6 or G9XA6G9XXA640
40 is for week 40. For example, a G9XXA640 would fall into production during the 40th week of the year.Next comes the lot number which I will show as @@@@@.
So a 3.7 revision chip could read G9XXA640@@@@@ or G9XA640@@@@@If your serial number starts with a GA, the following applies.
You have a 6x86L.
I hope that this makes sense.
Additionally, don't assume that just because you bought a Cyrix 6x86 recently you will be getting the latest revision. One never knows how long they are sitting in a back room before they are sold to a end user.
Q. How do I know what revision of the IBM 6x86 chip I have?
A. This information comes straight from IBM. On the front of the chip IBM places a part number that starts with "IBM266x86....." The last digit reflects the revision number. Revision 2.5 ends with "B". Revision 2.6 ends with "C". Revision 3.6 ends with "D". Revision 3.7 ends with "E". For example, a complete IBM 6x86 PR166+ revision 3.7 part number looks like IBM266x86-2V2P166GE.
The IBM 6x86L part numbers are slightly different. A complete 6x86L part number looks like IBM266x86L-2VAPxxxGB. The xxx is the PR rating value.
For a complete history of IBM 6x86 products, see http://www.chips.ibm.com/products/x86/x86prod/l3parthis.html.
Q. Can I download a utility that will tell me my 6x86 revision number?
A. Yes, you can download a small utility supplied by IBM that will identify the 6x86 CPU speed, stepping, and revision level. This method of revision determination will work for both the Cyrix and IBM 6x86. This utility will prevent you from having to pull the chip to obtain the revision number. According to IBM's web site, if the utility reports step 1, revision 5 it means you have a revision 2.5 chip. Step 1, revision 6, means 2.6. Step 1, revision 7 means Cyrix 2.7, Cyrix 3.7, or IBM 3.7. Unfortunately, the utility returns the same value for a Cyrix revision 2.7 or 3.7. In this case you must pull the chip and decipher the serial number to make the determination. Step 2, revision 2, means 4.2 or 6x86L.
Important! This utility doesn't generate a correct result under Windows NT. It needs to be run in MS-DOS or MS-DOS mode inorder to give a correct reading.
Q. What is the OFFICIAL Cyrix policy on how to get a replacement Cyrix 6x86?
A. Well, it was like pulling teeth, but I finally got the official Cyrix policy on the 6x86 replacement issue. I sent the following email to Cyrix tech support on 10/15/96.
My name is Bryan Davis, I am the author of the Cyrix 6x86 Upgrade Advice Guide. Many readers have asked me how to go about replacing their 6x86 CPU to get one of the latest 2.7 revision chips that do not have the NT 4.0 performance problem. What criteria must be meet inorder to get a replacement. Could you please give me your official policy on this matter so that I may pass it on to my readership. A non-response is an answer in itself. Any information would be greatly appreciated.
Thanks,
- BryanCyrix 6x86 Upgrade Advice Guide
http://www.ionet.net/~rbdavis/I received a response from Mark Plungy on 10/18/96. Mark is with Cyrix's public relations firm. Here is the answer.
Bryan:
I work for Cyrix's PR agency and your message about replacing a 6x86 was forwarded to me. Here is the situation with the Windows NT 4.0 issue. If a 6x86 users is experiencing a performance degradation in running NT 4.0, they need to contact tech support. They will need to verify that they are running NT 4.0 with a 6x86. They will work with that person on replacing the CPU or when a software patch is available providing that tool to the user. If you have any additional questions, let me know. I looked at what you had on your website about replacing the CPU and what you have is correct.
Regards,
Mark PlungyThe guessing game is over. Cyrix tech support should be your first point of contact if you are interested in getting a replacement chip.
Here is what others have to say about their replacement experience.
Lars Svensen provided the following information which he received from Cyrix tech support.
First, none of our processors are defective, buggy, or even remotely glitchy. The plain fact is that Microsoft wanted to release NT 4.0 as soon as possible. We were on the approved list for compatibility.
Our processor performed superbly throughout all the beta testing I and II. On one of the final stages of NT testing our unit produced a code during a small (almost minuscule) testing procedure. A sequence that any normal business/home user would never do.
In order to get our part to pass this tiny process with an acceptable response, they disabled the cache. If you know anything about timing issues and software compatibility, disabling the cache only slows down CPU processing across the board. That adjustment does not pin-point the source of the problem.
Instead of Microsoft attempting to figure out where the operating source code was causing the conflict or what timing issue was off, MS decided to slow everything down and claim a 30% performance loss on all Cyrix chips running NT 4.0.
All this mess was created b/c somebody didn't spend enough time with their OS and wanted an early release of the product. Further, MS tested the same process with a 2.7 (a couple steps higher than the original part tested) and the small test passed with a performance increase...supposedly)
After all this, MS notified us of our chips response in NT and explained their findings. Here at Cyrix we set up 10 machines with MS's configuration....After 170 hours of testing, we could not duplicate the problem. (go figure)
Enough about all of that..... We are offering a replacement CPU for registered NT 4.0 users who are unable to attain a replacement from their vendor. Call our technical support line at 800-462-9749.
Dennis O'Neill provided the following information which he received from Cyrix tech support.
The Cyrix 6x86 is certified for Win NT4.0. There are no compatibility issues with our processor and NT 4.0 but there was a performance issue according to MS. The problem, however, only came up in an internal test suite at MS in NT4.0. This problem has not been seen in any application. The 686 is listed on the NT 4.0 hardware compatible list.
Cyrix is working on a driver that will correctly configure the Cyrix processor for better performance in NT 4.0. At this point the driver is not in installable form but is being worked on. When ready it will be placed on out website and BBS for downloading.
If you buy Win NT 4.0 full version and you have a performance issue, then you will need to show us the proof of purchase Win NT 4.0 as well as the Cyrix chip and lot code. We will proceed from there.
Q. What is the IBM policy on how to get a replacement IBM 6x86?
A. On Thursday, November 7, Tomas Leete provided me with some up to date information that he received from IBM on this issue.
Tom sent the following email to IBM Internet Support.
From: tleete
To: "'askibm@info.ibm.com'" <askibm@info.ibm.com>
Subject: IBM6x86 revision 2.6 BUG
Date: Tue, 5 Nov 1996 18:45:32 -0500
I am an end user of an IBM6x86 PR166+ CPU (revision 2.6) purchased from a distributor on 8/29/96. As I understand it, these chips, and their Cyrix equivalents have a "bug" which Microsoft has gotten around by disabling the cache when the chip is used with the NT4.0 operating system thus decreasing performance by 30% and effectively making the chip useless under the NT4.0 operating system.In versions of the IBM and Cyrix 6x86 later than version 2.6 (i.e. ver. 2.7) this problem has been corrected. I would like to know how to go about exchanging my version 2.6 chip for non-defective (version 2.7) chip. Cyrix has agreed to exchanged chips sold under their name so I would assume IBM (since it is the same chip, with the same bug) is doing the same. Cyrix needs only to see the receipt of sale for the chip and a receipt for windows NT4.0 and a creditcard number to which the new chip can be charged IF the defective chip is not returned. I can fax this information to you upon request.
Thank you,
Thomas C. LeeteHe received the following responses:
Date: Wed, 6 Nov 1996 14:23:25 -0500
To: tleete
From: "askibm@VNET.IBM.COM" <askibm@VNET.IBM.COM>
Subject.: IBM6x86 revision 2.6 BUG
CALLOWN INTERNET RESPONSE FACILITY
Hello,
All information on these chips is available at http://www.chips.ibm.com. Since IBM does not sell these chips and only manufactures them as OEM, please refer to your point of purchase for all warranty and technical information. Thank you for using askIBM...
NINO BAGGIERI (tleete@WPI.EDU@vnet.ibm.com)
IBM Internet Support GroupAlso,
Date: Thu, 7 Nov 1996 18:22:32 -0500
To......: tleete
From: "askibm@VNET.IBM.COM" <askibm@VNET.IBM.COM>
Subject.: IBM 6x86 chip (revision 2.6)
CALLOWN INTERNET RESPONSE FACILITY
Hello Thomas,
IBM does provide 6x86 microchips to external vendors, but not to end-consumers.
For technical support or assistance with the 6x86 microchip please contact your local vendor or original place of purchase. Thank you for using ask IBM...
RYAN GREEN (tleete@wpi.edu@vnet.ibm.com)
IBM Internet Support GroupObviously IBM is aware of the 6x86 bug, but they want end users to get a replacement IBM 6x86 from the vendor that sold them the chip. Unfortunately, this puts you at the mercy of the point of purchase. I wonder how many IBM vendors are aware of the whole 6x86 and NT 4.0 debacle. I would hate to have to explain this one.
Once again IBM's dedication to customer service continues to shine. I have not heard of anyone who has had a successful IBM 6x86 exchange.
Q. Will Cyrix cross-ship a replacement 6x86?
A. Yes, after you contact Cyrix tech support, Cyrix will send you a cross-RMA form which you must fill out and fax or mail back to them. Cyrix requires a credit card number to do a cross-RMA return. As long as you send back the old CPU within 30 days you are not billed. Standard shipping is via FEDEX Economy (3 days), but you may pay a small additional amount to have the shipping upgraded to overnight. The replacement is normally shipped the day you send back the form.
Q. Is Cyrix still selling 6x86s that are below revision 2.7?
A. The answer is an unequivocal NO. However, I would ask any vendor before I purchased a 6x86 from them if I was getting a revision higher than 2.6. If they do not know what you are talking about, I would hang up the phone and call someone else. Once I did get someone who knew what I was talking about, I would make sure they had a return policy that would allow me to return the chip without a penalty just in case they thought they knew what they were talking about. This will help prevent you from getting burned by an ignorant vendor. Unfortunately, there are many of them out there.
Q. Is Cyrix still producing the 6x86L?
A. No, Cyrix/IBM is no longer dedicating previous silicon to the production of 6x86 or 6x86L wafers. As a result, the supply has finally dried up and authorized distributors are having a very difficult time getting 6x86 stock. The 6x86MX is now King.
Q. Can I still buy a standard voltage 6x86 part?
You will have a difficult time finding anyone selling the older standard voltage 6x86 CPU. Cyrix ramped up production of the 6x86L in the first quarter of 1997. The 6x86L eventually replaced the entire line of 3.xV 6x86 processors.
Cyrix also quit manufacturing the 6x86L PR150+ in 1997. The overwhelming majority of new 6x86 parts that are on market today are the 6x86L PR166+ and 6x86L PR200+.
Q. Why has Cyrix changed the naming convention of the 6x86 chip from Pxxx+ to PRxxx+?
A. Cyrix changed the naming convention of the 6x86 from Pxxx+ to PRxxx+. PR simply stands for Performance Rating and not Pentium Rating. The folks at Intel are responsible for this change in meaning. They threatened Cyrix/IBM with legal action for naming their 6x86 processors Pxxx+. Intel thinks that they own the letter P and Cyrix/IBM responded by changing the name to PRxxx+.
Q. Is SGS Thomson selling and manufacturing the Cyrix 6x86?
A. 6x86s with a ST6x86Pxxx+ label on the front of them are 6x86s that are being manufactured and sold by SGS Thomson. SGS Thomson is a giant global independent semiconductor supplier that designs, develops, and manufactures semiconductors. SGS Thomson has a manufacturing agreement with Cyrix very similar to IBM's.
The great thing about this is there is another set of serial and revision numbers to keep up with and we all can be confused about them even more than we already are. However, the ibmm1.exe utility should still report the proper revision number.
My recommendation: buy and be content with an Cyrix/IBM 6x86. Stay away from SGS-Thomson. According to Directlink.cgi-EBN19970331S0007 (www.techweb.com) their manufacturing process was so poor that Cyrix themselves didn't even buy the 6x86s that came off their fab lines.
