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AST RESEARCH TECHNICAL BULLETIN TB-0065 11-7-84
AT MOTHERBOARD MEMORY CONFIGURATION
1. An Advantage! installed in a 256K AT must be configured for
Split Memory Addressing as shown in Figure 3-4 in the User's
Manual. In a 512K AT, either Split Memory Addressing or
Contiguous Memory Addressing may be used on the Advantage!.
2. The AT system board may be configured with either 256K or
512K of memory. The position of a shorting plug on the
system board (J18) determines the proper configuration.
(J18 is located underneath the disk controller board near
the front of the AT chassis.)
Apparently some 256K ATs are shipped from IBM with the
jumper in the 512K position. This does not cause any
problems until an Advantage! is installed and configured for
the Split Memory Addressing mode. An addressing conflict
results: The "phantom" upper 256K on the system board
conflicts with the memory on the Advantage! and results in
errors during POST (typically 040002....210).
NOTE: As a portion of the data is in pictorial form, it is not
included here. To obtain a complete copy of this technical
bulletin, contact:
AST RESEARCH, INC.
2121 Alton Avenue
Irvine, California 92714
ATTENTION: Product Support
(Technical Bulletin)