33 lines
1.3 KiB
Plaintext
33 lines
1.3 KiB
Plaintext
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AST RESEARCH TECHNICAL BULLETIN TB-0003A 4-30-84
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MEMORY SWITCH ERROR IN IBM GUIDE
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TO OPERATIONS FOR IBM PORTABLE PC
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When extending the memory size of the IBM Portable PC beyond the
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128K minimum capacity of the system motherboard, the procedure is
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essentially the same as that for the XT.
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Additional memory may be installed on the I/O bus without first
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fully populating the motherboard. However, it is necessary to
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indicate the amount of motherboard memory installed via switches
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3 and 4 of the system motherboard switch block.
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Unfortunately, page 4-81 of the IBM Guide to Operations Manual
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erroneously shows that the switch position for 256K on the
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motherboard is switch 3 off and switch 4 on. This is actually
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the setting for 128K of RAM.
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The following is the proper settings for switches 3 and 4 of the
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system motherboard switch block.
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AMOUNT OF MEMORY SWITCH SWITCH
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INSTALLED ON MOTHERBOARD 3 4
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128K OFF ON
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192K ON OFF
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256K (fully populated) OFF OFF
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