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AST RESEARCH, INC.         TECHNICAL BULLETIN # 1022A               4-12-95

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		    AST EISA SYSTEMS WITH NCR SCSI HANG UNDER SCO UNIX


PROBLEM

AST EISA systems with an embedded NCR 53C810 PCI SCSI host adapter hang during 
boot, after installation of SCO UNIX rel. 3.2, ver. 4.2 while loading the 
file UNIX.TXT.


CAUSE

The on-board NCR SCSI adapter has a 1KB memory mapped resource region with a 
configurable address.  Because the EISA Configuration Utility (CU) configures 
the 1KB SCSI resource at the end of physical memory, UNIX writes to it when 
sizing memory, corrupting the SCSI adapter registers, and preventing further 
disk I/O.

SYSTEMS AFFECTED
AST PART NUMBER AND DESCRIPTION

501457-XXX          PREMMIA GX/P90
501500-XXX          MANHATTAN V-SERIES
501502-XXX          MANHATTAN P-SERIES


SOLUTION

The SCSI adapter resource buffer address must be relocated before booting UNIX. 

Use the EISA CU to set the address of the 1K resource region to a value that 
is beyond the end of the system's physical memory.  

To change the resource region address through EISA CU do the following:

	RUN         EISA-CU (version 3.02 or later)
	SELECT      Step 3: View or Edit Details
	SELECT      Embedded - PCI Board
			  PCI Function 1      Enabled
	PRESS <F6>  Edit Resources
	SELECT      Memory Address
	PRESS <+>   Until display reads 128M (or greater than system memory size)
	PRESS <F10> Save and Exit