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Atari Technical Bulletin
Number: ABC286-0001
Date: November 11, 1991
Page 1 of 3


Product(s) Affected:	ABC 286, PC4X
Model:				ABC 286/12/16, PC4X-12MHZ, PC4X-16MHZ
Type of ATB:			As Needed
ECO #:				N/A

Reason for ATB:

1.)	Field reporting problems with HIMEM not loading after the line 'DEVICE=HIMEM.SYS' is added to the CONFIG.SYS file.

2.)	This remedy will also cure the problems where software being loaded through an INSTALL program reports 'COMPACT FILE ERRORS'.

3.)	This procedure will also cure any problem with applications attempting to access protected mode.


Notes:

PC4X-Bios revision 1.7, part numbers C301768-002 and C301769-001 has been identified with this problem.


Symptoms of Problem:

1.)	If the line 'DEVICE=HIMEM.SYS' is in your CONFIG.SYS file and an error message appears on screen after system MEMORY test:

ERROR: Unrecognized A20 hardware
XMS Driver not installed


2.)	Software being loaded through an INSTALL program reports:

"COMPACT FILE ERRORS".


3.)	Errors with applications attempting to access protected mode.

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Atari Technical Bulletin
Number:	 ABC286-0001
Date: November 11, 1991
Page 2 of 3

Tests to Determine if Problem Exists:

TEST for Symptom 1

Turn on computer.  While the system is booting, look for the message on the screen:

HIMEM:  DOS XMS Driver, Version X.xx - mm/dd/yy
Copyright 19xx, Microsoft Corp.

64K High Memory Area is available


If this message appears, then you do not have a problem.  However, if the following error message appears:

ERROR: Unrecognized A20 hardware
XMS Driver not installed

Read and follow the 'SOLUTION' section of this Technical Bulletin.

**NOTE**  If neither message appears on the screen (no mention of HIMEM Driver at all) then you will need to add the line:

'DEVICE=HIMEM.SYS' to your CONFIG.SYS file.

(Be sure the file 'HIMEM.SYS' is in your root directory)

TEST for Symptom 2 and 3

If you are having one of the other problems listed under the 'Symptoms of Problem' heading in this Technical Bulletin, then read and follow the 'Solution' section.

Solution:

1.)	Boot system from a Cold Boot (from a powered down condition to a powered up condition).  After the MEMORY test is completed, Press the  DEL key after the message:

Press DEL if you want to run SETUP/EXTD-SET

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Atari Technical Bulletin
Number: ABC286-0001
Date: November 11, 1991
Page 3 of 3


Use the down arrow key to highlight RUN XCMOS SETUP, and hit <ENTER>.

**NOTE** If EXTD-SET option does not exist, you have an earlier BIOS Rom version.

If this is the case, Insert the MS-DOS/Utilities Disk that came with your computer and type:

A: <ENTER>.

At the A> prompt, type cd util <ENTER>.

Now type neat <ENTER>.

2.)	Use the down arrow key to highlight:

ADVANCED NEAT CHIPSET REGISTER SETUP, and then hit <ENTER>.

3.)	Hit the <ENTER> key again to continue.  Use the down arrow key to scroll down to 6FH under the 82C212B heading.  Use the right arrow key to highlight Bit 1 of 6FH.  The Dialogue Box on the right side of the screen should show:

Miscellaneous Register RB12

Enable CPUA20 onto A20
0=Enable
1=Disable

This definition of the Bit is incorrect. The true definition is:

0=Disable   1=Enable

4.)	Use the PgDn key to toggle this bit to a 1.  Hit the <Esc> key to return to the MAIN MENU.  Use the down arrow key to highlight:

WRITE CMOS REGISTERS AND EXIT

5.)	System will re-boot automatically.  After the MEMORY test, the screen  will display:

HIMEM:  DOS XMS Driver, Version 2.04 - 8/17/88
Copyright 1988, Microsoft Corp.

64K High Memory Area is available.