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AST RESEARCH, INC.        TECHNICAL BULLETIN # 1164                  5-3-95

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			  MANHATTAN P OR V TOSHIBA DRAM COMPATIBILITY


PROBLEM

One type of Toshiba TC5117400 DRAM is incompatible with the memory paging 
feature introduced in BIOS release 1.09.  


ERROR SYMPTOMS

AST has confirmed the DRAM can cause the following errors:

The computer hangs or freezes without an error code.

The computer reports a parity error has occurred.

The computer reports a  "Unexpected Non-Maskable Interrupt" error has 
occurred.

The computer reports  "NVRAM BAD".


SYSTEMS AFFECTED
AST PART NUMBER AND DESCRIPTION

501500-XXX     MANHATTAN V5090
501502-XXX     MANHATTAN P5090


SOLUTION

Use TOSHIBA DRAMs that are compatible with the memory paging feature 
introduced in BIOS version 1.09.


IDENTIFYING THE INCOMPATIBLE TOSHIBA TC5117400 DRAMs

Inspect the DRAMs on the SIMM.  The incompatible DRAM has one of the following 
Toshiba part numbers marked on top of the chip:

TC5117400J-XX
TC5117400SJ-XX 
(where XX is either 60 or 70, indicating DRAM access time in nanoseconds)


IDENTIFYING THE COMPATIBLE TOSHIBA TC5117400 DRAMs

Toshiba is now producing revision B of the TC5117400 DRAM.  Revision B is 
100% compatible and does not cause problems. To verify the DRAM is compatible, 
inspect the part number that is located on the top of the DRAM chip for the 
letter "B".  For example, the following part numbers are acceptable:

TC5117400BJ-XX.
TC5117400BSJ-XX

ADDITIONAL INFORMATION

Any SIMM manufacturer may have used the incompatible TOSHIBA DRAM when they 
manufactured their SIMM module.  SIMM modules consist of small silicon chips 
that are soldered onto a small Printed Circuit Board (PCB).  Most of the small 
silicon chips are called DRAMs (Dynamic Random Access Memory).  When SIMM 
modules are manufactured, several different DRAM manufacturers can be 
installed on the PCB.  This Technical Bulletin discusses only the DRAM that 
is soldered on the SIMM module.

Please review Software Bulletin # 0178C for additional information regarding 
BIOS release 1.09.