AST Research, Inc.      Technical Bulletin # 1296               8/21/95



                    Bravo MS P/90 Video Shadow Effect


PROBLEM: 

The Bravo MS P/90 system may have a strong video "shadow effect".

CAUSE:

The problem is caused by noise sensitivity of the feature connector from 
the Cirrus Logic 543x video chipset.

SYSTEMS AFFECTED:

501651-XXX                    Bravo MS P/90
501533-XXX                    Bravo MS P/60

SOLUTION:

There different solutions for each independent OS video driver.

DOS/Windows

1.  Download the file <A HREF="ftp://ftp.ast.com/D-VIDEO/P-BUS.EXE">P-BUS.EXE</A> from AST On-Line! BBS.
 
2.  Copy the file into a temporary directory. Once copied type P-BUS for the 
    file to self-extract.

3.  At the DOS prompt type 5434_DOS to disable or enable the feature connector.   
     
     For those user who need to use the feature connector, do not 
     run this program.



WINDOWS NT

1.  Download the file <A HREF="ftp://ftp.ast.com/D-VIDEO/P-BUS.EXE">P-BUS.EXE</A> from AST On-Line! BBS.

2.  Copy the file into a temporary directory on the hard drive. Once copied  
    type P-BUS for the file to self-extract. Copy the files to a blank diskette.

3.  Run the program 5434_NT to disable or enable the   
    feature connector with diskette in drive A:.

OS/2 (3.0) WARP 

1. Please refer to the video installation section on the OS/2 Drivers Installation    
    Manual.
    
    Use Setup.cmd to install the Corrective Service Pack and then use OS/2's    
    Display drivers install to install the new version of the display drivers.

    After installation is complete modify SVGADATA.PMI    
    by adding two additional statements on the first [LOCK] field.

[LOCK]

outb(0x3c4,0x18);
outb(0x3c5,0xc0);

     This modification in the SVGADATA.PMI will turn off the feature   
     connector. If the feature connector is needed, do not modify the  
     SVGADATA.PMI file.

CAUTION

This modification should be performed ONLY by a qualified service technician.  
It is strongly recommended that this change be completed by an AST Authorized 
Service Center.  In no case will AST Research, Inc. be liable for damage to 
the system and its components, or loss of data caused by improper modification.

PREREQUISITES

A full backup of all data on the hard drive in the computer is strongly suggested.



TIME REQUIRED

30 minutes.

CHECK-OUT PROCEDURE

To verify shadow effect has been eliminated.