1.1 Why Read This Document
The VAX 6000 series platform has changed to accommodate
features of the VAX 6000 Model 500. Several XMI I/O adapters
are also now available and can be installed in any XMI card
cage. A new power regulator, capable of providing enough
current at +3.3 volts for the VAX Model 500, is inhibited in
the H9657 cabinet for Models 300 and 400. A more powerful
battery backup unit (BBU) option, capable of providing
power to the entire backplane, is available.
Table 1–1: VAX 6000 Platform Differences
Item XMI-1 Platform XMI-2 Platform
XMI backplane XMI-1 XMI-2
Cabinet number 70-24900-XX H9657-XX
XMI I/O adapters DWMBA CIXCD, DEMNA,
KDM70, DWMBB
VAXBI Required
DWMBA adapter
Two 6-slot channels
Optional
1
DWMBB adapter
One 12-slot channel
Load device TK50 or TK70 Optional
1
XTC 20–29176-01 20–29176-02
Power regulators +5V – H7214
+5VBB – H7214
-5, -2,
12 – H7215
+5V – H7214
+5VBB – None
2
-5, -2,
12 – H7215
+3.3V – H7242
Power logic H7206-A H7206-B
Battery backup H7231-N H7236-A
2
Inhibit cable None 17-02522-01
1
Either a VAXBI with a TK70 or a CD server is required as a system load de-
vice.
2
In the XMI-2 backplane +5V and what was +5VBB are tied together. Since the
VAX 6000 Model 500 uses a writeback cache design, the CPU’s cache also needed bat-
tery backup and the need for a separate +5VBB to back up only memory disap-
peared. The H7236-A BBU delivers more power than the H7231-N BBU.
1–2 VAX 6000 Models 300 and 400 Service Manual
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