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Table B-3 VMB Boot Options
Bit
Function
Conversational boot. The secondary bootstrap program, SYS-
0
BOOT, prompts you for system parameters at the console
terminal.
Debug. If this bit is set, the operating system maps the code
1
for the XDELTA debugger into the system page tables of the
running operating system.
Initial breakpoint. If this bit is set, the operating system exe-
2
cutes a breakpoint (BPT) instruction early in the bootstrap
program.
3
Secondary boot from bootblock. The secondary boot is a sin-
gle 512-byte block whose logical block number is specified in
the General Purpose Register R4.
4
Not used.
Boot breakpoint. This stops the primary and secondary load-
5
ers with a breakpoint (BPT) instruction before testing mem-
ory.
6
Image header. The transfer address of the secondary loader
image comes from the image header for that file. If this bit is
not set, control shifts to the first byte of the secondary
loader.
File name. APB or VMB prompts for the name of a secon-
8
dary loader.
Halt before transfer. APB or VMB executes a HALT instruc-
9
tion before transferring control to the secondary loader.
No effect, since console program tests memory.
13
Not used.
15
Do not discard CRD pages.
16
Specifies the top-level directory number for system disks.
31:28
B-4 Boot Options
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