Compaq Compaq Portable II, Maintenance And Service Manual

Page: 37 / 118

04 U9 U12 Replace memory chip
08 U41 U42 Replace memory chip
10 U33 U34 Replace memory chip
20 U25 U26 Replace memory chip
40 U18 U19 Replace memory chip
80 U10 U11 Replace memory chip
------------------------------------------------------------------------------
XX = 08 (Bank 1)
------------------------------------------------------------------------------
Data Bit
B = 0 B = 1
YY or ZZ Low High Required Action
------------------------------------------------------------------------------
00
U40 U43 Replace system board
01 U31 U16 Replace system board
02 U31 U16 Replace system board
04 U31 U16 Replace system board
08 U31 U16 Replace system board
10 U23 U8 Replace system board
20 U23 U8 Replace system board
40 U23 U8 Replace system board
80 U23 U8 Replace system board
==============================================================================
Defective Memory Chip Isolation Map for the 512/1536 Kbyte System Memory
Board Mapped into the 1 to 2.5 Megabyte Memory Space (256K x 1 Bit RAMs)
NOTE: This isolation map is valid for a system memory board that uses
256K x 1 bit RAMs.
Memory error codes are in the format XX000B YYZZ.
XX equals the 128 Kbyte memory segment where an error is detected.
000 is always equal to 000 (not used).
B Byte bank location (Low: B = 0, High: B = 1)
YY Bit location of the low byte (B = 0)
ZZ Bit location of the high byte (B = 1)
Use the following table to locate the defective memory chip and the required
action.
Figure 5-3 shows the memory chip locations for the COMPAQ
PORTABLE II Personal Computer System Memory Board (512/1536 Kbyte). For
information on removing and replacing memory chips contained on this board,