+------------------------------------------------------------------------+
¦ Paired Memory ¦ Memory Bank Size ¦ Memory Block ¦ Memory Now ¦
¦ Kits ¦ ¦ Disabled ¦ Usable ¦
+-----------------+------------------+-----------------+-----------------¦
¦ ¦ ¦ ¦ ¦
¦ J1 J3 ¦ J1 J3 ¦ ¦ ¦
¦ 1MB 1MB ¦ 1MB 1MB ¦ 2MB ¦ 0MB ¦
¦ 2MB 2MB ¦ 1MB 1MB ¦ 2MB ¦ 2MB ¦
¦ 4MB 4MB ¦ 4MB 4MB ¦ 8MB ¦ 0MB ¦
¦ 8MB 8MB ¦ 4MB 4MB ¦ 8MB ¦ 8MB ¦
¦ ¦ ¦ ¦ ¦
+------------------------------------------------------------------------+
Minimum memory-block size is 2MB for 1MB and 2MB memory-module kits and
8MB for larger memory-module kits.
Note: If a system with only two 1MB kits (one 2MB block) or two 4MB kits
(one 8MB block) installed detects a memory problem, all
system-board memory will be disabled. (These are not standard
configurations and should be avoided.)
If the POST detects an error in the first block of system-board memory,
that block is disabled. If additional system-board memory is installed,
the addresses assigned to the deactivated blocks are reassigned to the
next usable block of system-board memory and a POST error code is
displayed.
If an additional block of system-board memory is installed, the
customer-level diagnostic programs (on the default hard disk drive) can be
run to deactivate the defective block and reassign the memory addresses.
The system can then operate with reduced memory capacity. The defective
block will then be ignored by POST during subsequent power-on operations.
If an additional block of system-board memory is not installed, no address
reassignment can occur and the system can't be used.
Memory Errors (Type 2 Systems): Some memory errors will cause a blank
display screen. If the display screen is blank, a POST error code can't
be displayed.
If the memory is installed in an interleaved configuration, the system
will operate as described under Memory (Type 1 systems); however, memory
errors are handled differently. If an error occurs in an interleaved
memory configuration, the pair of memory module kits containing the error
will automatically be switched to noninterleaved operation to keep the
maximum amount of memory active. Only the failing bank of memory will be
disabled.
The following figure shows how the amount of memory that is disabled
varies depending on the size of the memory-module kit installed.
+------------------------------------------------------------------------+
¦ Memory Module Kit installed ¦ Memory Bank Size Disabled ¦
+------------------------------------+-----------------------------------¦
¦ ¦ ¦
¦ 2MB ¦ 1MB ¦
¦ 4MB ¦ 4MB ¦
¦ 8MB ¦ 4MB ¦
¦ ¦ ¦
+------------------------------------------------------------------------+
Note: If a system with only one 1MB kit or one 4MB kit installed detects
a memory failure, all system-board memory will be disabled. (These
are not standard configurations and should be avoided.)
If the POST detects an error in the first bank of system-board memory,
that bank is disabled. If additional system-board memory is installed,
the addresses assigned to the deactivated banks are reassigned to the next
usable bank of system-board memory and a POST error code is displayed.
If an additional bank of system-board memory is installed, the
customer-level diagnostic programs (on the default hard disk drive) can be
run to deactivate the defective bank and reassign the memory addresses.
The system can then operate with reduced memory capacity. The defective
bank will then be ignored by POST during subsequent power-on operations.
If additional system-board memory is not installed, no address
reassignment can occur and the system can't be used.
IBM PS/2 Model 90 XP 486 HMR
System Memory
¦ Copyright IBM Corp. 1990, 1991
1.3 - 2
