NOVELL TECHNICAL INFORMATION DOCUMENT

DOCUMENT PROCESSING INFO:
TITLE:  ADDRESS LINE OR GATE A20 MESSAGES
DOCUMENT ID:  TID800061
DOCUMENT REVISION:  A
DATE:  18AUG94
AUTHOR:  SNICOSIA;CEREKSON
ALERT STATUS:  Yellow
DISTRIBUTION:  Public
INFORMATION TYPE:  Symptom Solution
README FOR:  NA
NOVELL PRODUCT CLASS:

Desktop Products

NOVELL PRODUCT and VERSION:

DR DOS 6.0

CATEGORY:

Memory

ABSTRACT:

N/A

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THE ORIGIN OF THIS INFORMATION MAY BE INTERNAL OR EXTERNAL TO NOVELL. 
NOVELL MAKES EVERY EFFORT WITHIN ITS MEANS TO VERIFY THIS INFORMATION. 
HOWEVER, THE INFORMATION PROVIDED IN THIS DOCUMENT IS FOR YOUR INFORMATION
ONLY.  NOVELL MAKES NO EXPLICIT OR IMPLIED CLAIMS TO THE VALIDITY OF THIS
INFORMATION.
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SYMPTOM

SYMPTOM:

MESSAGES: ADDRESS LINE A20 ALREADY ENABLED OR CANNOT CONTROL ADDRESS LINE
A20.

CAUSE

ISSUE/PROBLEM:

After a warm boot some PS/2 machines produce the message "Gate A-20
already Enabled".  Some 286, 386 and 486 machines may generate the
message "Cannot control address line A20".

Some machines may also have a problem printing if GATE A20 is enabled. If
the port seems to hang as though the printer is off line, then GATE A20
may be the culprit.

SOLUTION

SOLUTION:

Try the following solutions:

1.  Turn off GATE A20 in the CMOS (if it is enabled)

2.  Use the switch /GATEA20=PS2 (on HIDOS.SYS or on EMM386.SYS)

The /GATEA20=PS2 switch was implemented with updated DR DOS 6.0 files
dated 4/7/92 or later.

NOTE:  Some mother boards have been found to set GATE A20 as active.
If so, it will conflict with ANY protected mode program such as the
EMM386.SYS driver that comes with DR DOS 6.0.

Newer version mother boards do not automatically set the GATE A20 to on
and should work correctly.

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