Cisco 7000 Hardware Installation And Maintenance page 180

Installing and Configuring Processor Modules
Step 5
Step 6
Bit Meanings
The lowest four bits of the software configuration register (bits 3, 2, 1, and 0) form the boot field.
(See Table 5-5.) The boot field specifies a number in binary form. If you set the boot field value to
0, you must boot the operating system manually by entering the b command at the bootstrap prompt
as follows:
Definitions of the various b command options follow:
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Note
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For more information about the b [tftp] flash filename command, refer to the set of router products
configuration publications.
If you set the boot field value to 0x2 through 0xF, and there is a valid system boot command stored
in the configuration file, then the router boots the system software as directed by that value. If you
set the boot field to any other bit pattern, the router uses the resulting number to form a default boot
filename for netbooting. (See Table 5-6.)
5-176 Cisco 7000 Hardware Installation and Maintenance
To display the configuration register value currently in effect and the value that will be used
at the next reload, enter the show version EXEC command. The value will be displayed on
the last line of the screen display, as in the example following:
Configuration register is 0x141 (will be 0x101 at next reload)
Reboot the router. The new value takes effect. Configuration register changes take effect
only when the server restarts, such as when you switch the power OFF and on or when you
issue a reload command from the console.
If the boot ROMs do not support the software configuration register (not IOS Release 10.0
or later), the following message will be displayed:
Boot ROMs do not support software configuration register.
Value not written to NVRAM.
> b [tftp] flash filename
b—Boots the default system software from ROM
The RSP7000 does not use ROM devices to run Cisco IOS images.
b flash—Boots the first file in Flash memory
b slot0: filename—Boots the file filename from the Flash memory card in the PCMCIA slot on
the faceplate
b filename [host]—Netboots using TFTP
b flash [filename]—Boots the file filename from Flash memory