Digital Equipment DECstation 5000/100 Series, Maintenance Manual

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CPU Module
CPU Module Hardware Description
The system module holds one of the following removable CPU
modules:
20-MHz CPU module
25-MHz CPU module
33-MHz CPU module
50-MHz CPU module
A Model 120 system has a 20-MHz CPU module, a Model 125
system has a 25-MHz CPU module, and a Model 133 system
has a 33-MHz CPU module. The 20- and 25-MHz CPU modules
are similar in appearance. A label on the CPU module specifies
whether it is a 20-MHz or 25-MHz module. A Model 150
includes a 50-MHz CPU. If your system has been upgraded
from a Model 120, 125, or 133 to a 150 the 50-MHz module is
distinguished by a single ASIC chip, and single CPU chip with
a rectangular shaped heatsink mounted on top of the CPU.
To distinguish between 20-, 25-, 33-, and 50-MHz CPU modules
functionally, run the CPU type test by entering the t command
in console mode:
t 3/misc/cpu-type
If the CPU speed is 20 MHz, the system returns the following
message:
3/misc/cpu-type’s code: NDX-91A
If the CPU speed is 25 MHz, the system returns the following
message:
3/misc/cpu-type’s code: NDX-97A
If the CPU speed is 33 MHz, the system returns the following
message:
3/misc/cpu-type’s code: NDX-103A
Base System FRUs 5–9