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AST RESEARCH, INC.        TECHNICAL BULLETIN # 1199                 5-30-95

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IDENTIFYING PENTIUM PROCESSOR REVISIONS

This is an informational bulletin.

ISSUE

Some early versions of the Intel Pentium P54C processors contained errata 
that led to imperfect floating point performance. Users of these processors 
may need to upgrade to a later version of the processor to avoid any 
mathematical irregularities.  This bulletin will help identify the revisions 
and dated processor lots that may need to be upgraded.

NOTE:  See Field Change Notices 0175-0189 for more information on the nature 
of the errors, the process for receiving new processors, and help in making 
a determination as to whether the update is necessary in your system.  

Field Change Notices 0175-0189 are located in the FCNS library of AST's BBS.  
AST's BBS may be reached by dialing (817) 230-6850, in the "Systems" file 
area.  AST's BBS supports modem speeds up to 28.8k bps.  The above file will 
also be posted on: 

CompuServe 
Go ASTSUPPORT

AST Worldwide Web Site
http://www.ast.com


Processors exhibiting decreased floating point performance can be identified 
by either 

1) a software test
2) the revision level stamped on the Pentium processor itself
or
3) by the serial number of the unit in which the Pentium processor 
is installed.


IDENTIFICATION BY SOFTWARE

Using the Microsoft Windows Calculator program, or any program that performs 
long division and displays the result to the 8th decimal place, enter the 
following mathematical calculation:

5,505,001 divided by 294,911

The correct answer is: 18.66665197
The incorrect answer is: 18.66600093

If the system displays the correct answer, the processor is not affected by 
the errata.

An alternate calculation is:

4,195,835 divided by 3,145,727

The correct answer is: 1.33382045
The incorrect answer is: 1.33373907

If the system displays the correct answer, the processor is not affected by 
the errata.


IDENTIFICATION BY PROCESSOR REVISION

The Intel Pentium processor bears a printed revision level on its top (smooth) 
side face.  However, these markings will most often be covered by a heatsink.  
If a heatsink is in place on the processor, use either the software method or 
the serial number method to identify the processor revision.  Removing the 
heatsink may damage the processor itself.

If no heatsink is installed, then check the processor revision against 
the table below:

NOTE: In general, 60MHz and 66MHz processors (5 volt) must be at stepping D1 
or higher to be considered corrected.  75MHz, 90MHz, 100MHz processors 
(3.3 volt) must be stepping B5 or higher to be considered corrected.

Intel Product Code           Socket Type     Speed (MHz)       Min. Step

TT8050250-75                 TCP                  75               B5
A8050250-75  SX961           PGA                  75               B5
A8050250-90  SX957           PGA                  90               B5
A8050250-90  SX958           PGA                  90               B5
A8050266-100  SX962          PGA                 100               B5
A80501-66  SX948             PGA                  66               D1
A80501-66  SX949VR           PGA                  66               D1
A80501-66  SX950             PGA                  66               D1


IDENTIFICATION OF AST SYSTEMS BY SERIAL NUMBER

The serial number on the back of the system will also identify which units 
contain processors below the corrected revision levels.

The serial number is a twelve (12) digit number and letter combination which 
appears on the back of the system, or may be displayed in System Setup.  
See the User's Manual included with the system for help in locating the 
computer's serial number.

The serial number is date-coded, by the first three digits.  Reading from the 
left to the right, the first two digits indicate the calendar week the system 
was manufactured.  The third digit is the last digit of the year in which the 
system was manufactured.

EXAMPLE:

125AEO000095

The 12 indicates that the system was manufactured in week twelve of the year.

The 5 indicates that the system was manufactured in 1995.

For Premmia, Bravo, and Manhattan systems:

To identify those systems that were manufactured before the availability of 
corrected Pentium processors, look for a date code EARLIER than 045 
(fourth week of 1995).  These systems may require replacement of their 
processors.

For Advantage! systems with 60MHz processors:

To identify those systems that were manufactured before the availability of 
corrected Pentium processors, look for a date code EARLIER than 045 
(fourth week of 1995).  These systems may require replacement of their 
processors.

For Advantage! systems with 90MHz processors:

To identify those systems that were manufactured before the availability of 
corrected Pentium processors, look for a date code EARLIER than 085 
(Eighth week of 1995).  These systems may require replacement of their 
processors.