Megabyte Memory Healing - HP 9020 Service Manual

2-28
Theory of Operation
When all 32 locations of the healer are full, no further healing or automatic changes to the healer
CAM occur on that Memory Controller. When all healer locations have been used, the healer
overflow bit in the MC status register is set. When all healer locations are full, the operating system
checks each healed location to determine if the location is still faulty. If the location fault was caused
by a momentary failure, the overflowed CAM can be cleared and reused by the operating system.
HEALER CAM
(ADDRESS)
HEALER RAM
(DATA)
o
31
o
31 32 39
DATA
•
•
•
•
•
•
I
C~ii:
1 0
1
31
..... _----------
..... _ _ _ _ _ _ _ _ _ _ _
~131
/
--
/
/
( 0 1
,--_..,.,A, _ _ .....
I ,
1-HEALED LOCATION
-- -- -- --
10 11
28 29
xl
X AND Y ADDRESS
Ix
~
PHYSICAL MEMORY ADDRESS---.J
r-
(18
BITS)
~
X-DON'T CARE
Figure 2-18. 1 Megabyte Memory Healing
--
J
X
xl