Table 4–33 Dispatch Block Components
Block Content
Offset
Description
Dispatch reason
code
Base + 00h
4 bytes
Code identifying reset reason. Bytes 03:02
identify the reason for the reset.
Bytes 01:00 identify the end action to be taken by
the console as specified below:
•
00 = POWERUP. Default or unexpected reset.
Run diagnostics and halt (enter the console).
•
01 = NO_DIAGS. Halt (enter the console).
•
02 = DISPATCH. Dispatch requested. Jump
to the dispatch address.
•
03 = RESYNCH. Resynch reset. Jump to the
dispatch address.
•
04 = DIAGS. Run diagnostics and halt (enter
the console).
•
05 = STOP_ZONE. OpenVMS issued a STOP_
ZONE. Run diagnostics and halt (enter the
console).
•
06 = RECONFIG. Reconfigure firmware (for
firmware use only).
Dispatch address
Base + 04h
8 bytes
Physical address where console will jump. In the
Model 810, only the first 4 bytes are used. Upper
4 bytes must be 0.
Dispatch reason
complement
Base = 0Ch
4 bytes
The 1’s complement of the dispatch reason code.
Used for checking the dispatch block validity.
4.8.1.3 Boot Parameter Block Description
The boot parameter block (BPB) is a structure built by firmware to reflect the
primary bootstrap code (VMB) of the boot device that is used during the bootstrap
sequence. Table 4–34 describes the BPB components. Table 4–35 describes the
entry components in the DCB structure.
Table 4–34 BPB Components
Component
Length
Description
Number of
entries
4 bytes
Number of entries in the BPB. Written by firmware. Is 0 if
no entries are present.
BPB entries
5 bytes
per entry
An entry describes a boot path. Written by firmware.
Maximum number of entries is 32. (See Table 4–35 for
entry description.)
4–60 Error Handling and Analysis