B-4 AlphaServer GS80 Upgrade Manual
Table B– 1 Comparison of CPUs (Continued)
CPU Part
Number
B-cache
Size
Speed
in MHz
Comments
B4168 Uses 4 of
its 16 MB
B-cache
1148 The B4168 runs at this speed when placed in a QBB
that supports only 4 Mbytes of B-cache, when all
CPUs in the system are B4168 or B4166, and the
clock runs at 9.0 ns.
Uses 8 of
its 16 MB
B-cache
1001 The B4168 runs at this speed and uses 8 Mbytes of its
B-cache when the B4168 is placed in the same QBB
as the B4166 and the clock is at 9.0 ns.
4 or 8
Mbytes
940 The B4168 runs at this speed when all CPUs in the
QBB are B4168 or B4166, and the system clock runs
at 9.6 ns. If the system box duplicate tag supports
only 4-MB or 8-MB cache, then only 4 or 8 of the 16
Mbytes of B-cache on the CPU are used.
Uses 4 of
its 16 MB
B-cache
731 The B4168 runs at this speed and uses 4 Mbytes of its
B-cache when the B4168 is placed in the same QBB as
the B4125 and the clock is at 9.6 ns.
Table B– 2 Comparison of System Drawers
System Drawer
Part Number
Cache Size
Supported
by Drawer
Comments
BA52A-AA
(54-30354-03)
4 Mbytes Though the B4166 and B4168 CPUs have larger B-
caches, only 4 Mbytes are used when placed in this
backplane.
BA52A-CA
(54-30354-02)
4 or 8
Mbytes
When CPUs in this backplane are B4166 or B4168,
they use 8 Mbytes of B-cache. If a B4125 is mixed
with other speed CPUs on the same backplane, all are
configured for the 4-Mbyte B-cache size.
BA52A-DA
(54-30360-02)
4 , 8, or 16
Mbytes
When all CPUs in this backplane are B4168, they use
16 Mbytes of B-cache. If CPUs are mixed, B4125,
B4166, or B4168 on the same backplane, all are
configured for the B-cache size of the processor that
supports the smallest size (4 or 8 Mbytes).
