Digital Equipment AXPpci 33, Руководство по конструкции

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Physical Description
Figure 2–9 Cache Socket
MR-6398-AI
2.2.4 MLB Jumpers
The MLB has numerous sets of jumpers, which are described in Sections
2.2.4.1–2.2.4.6. The jumpers are installed onto unshrouded headers that
consist of 0.025 inch square posts on 0.1 inch centers. When jumper plugs
are not used for shorting two pins, they may be stored by pushing them
onto a single post.
2.2.4.1 Cache Speed Select (J17)
J17 is a 2-position (1 x 2) header. The processor is informed of what
speed cache memories are installed through this jumper, as outlined in
Table 2–19.
Table 2–19 Cache Speed Select Jumper (J17)
15 ns Cache 20 ns Cache
1
Jumper out Jumper in
1
Factory default
2.2.4.2 CPU Clock Frequency Select Jumper (J7)
J7 is a 6-position (2 x 3) header used to select the Alpha processor clock
frequency. This jumper provides the processor with information about the
clock speed to program a phase lock loop (PLL) circuit for the appropriate
frequency.
2–20