52 lines
2.0 KiB
Plaintext
52 lines
2.0 KiB
Plaintext
=============================================================================
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AST RESEARCH, INC. TECHNICAL BULLETIN #0789 11-19-92
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=============================================================================
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PREMIUM 486/25 SYSTEMS AND NOVELL NON-DEDICATED NETWARE 2.2
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PROBLEM: After installing an Intel Overdrive processor (ODPR486DX-25)
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into an AST Premium 486/25 system configured with Novell Non-
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Dedicated Netware 2.2, the system will briefly display the
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message "ABEND: Double Exception Interrupt" and then reboot
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when attempting to start the server.
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CAUSE: Novell Netware 2.2 uses timing dependent loops when toggling
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the status of the GATEA20 line. With the Intel Overdrive chip
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installed, this loop executes so quickly that the GATEA20 line
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is not set to the proper state before Netware begins accessing
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extended memory.
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AFFECTED
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SYSTEMS: AST CUPID Desktop Systems (motherboard part number 202356-00X
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& 202337-00X).
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SOLUTION: The file NET$OS.EXE may be patched to increase the length of
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the timing dependent loops. The following procedure uses the
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DOS DEBUG command to implement this fix:
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c:\>copy net$os.exe net$os.bin<cr>
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debug net$os.bin
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- s 100 FFFF 8B 0E 71 05<cr>
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xxxx:yyyy
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- e xxxx:yyyy<cr>
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xxxx:yyyy 8B.B9<space> 0E.C0<space> 71.00<space> 05.90<cr>
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- s (x+1)xxx:0000 FFFF 8B 0E C8 4B
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XXXX:YYYY
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- e XXXX:YYYY
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XXXX:YYYY 8B.B9<space> 0E.C0<space> C8.00<space> 4B.90<cr>
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-w<cr>
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Writing zzzzz bytes
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-q<cr>
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C:\>copy net$os.exe net$os.old<cr>
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1 file(s) copied
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C:\>copy net$os.bin net$os.exe<cr>
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1 file(s) copied
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