34
Configuring the Software Configuration Register
78-4339-09
Implementing Additional Configuration and Maintenance Tasks
Bit 8 controls the console Break key. Setting bit 8 (the factory default) causes the system to ignore the
console Break key. Clearing bit 8 causes the system to interpret the Break key as a command, which
forces the system into the bootstrap (or ROM) monitor, thereby halting normal operation. Regardless of
the setting of the break enable bit, a break causes a return to the ROM monitor during the first few
seconds (approximately 5 seconds) of booting.
Bit 9 is unused.
Bit 10 controls the host portion of the IP broadcast address. Setting bit 10 causes the processor to use all
zeros; clearing bit 10 (the factory default) causes the processor to use all ones. Bit 10 interacts with
bit 14, which controls the network and subnet portions of the broadcast address.
Table 12
shows the combined effect of bits 10 and 14.
Bits 11 and 12 in the configuration register determine the data transmission rate of the console terminal.
Table 13
shows the bit settings for the four available rates. (The factory-set default data transmission rate
is 9600.)
cisco4-GRP
0
1
0
0
cisco5-GRP
0
1
0
1
cisco6-GRP
0
1
1
0
cisco7-GRP
0
1
1
1
cisco10-GRP
1
0
0
0
cisco11-GRP
1
0
0
1
cisco12-GRP
1
0
1
0
cisco13-GRP
1
0
1
1
cisco14-GRP
1
1
0
0
cisco15-GRP
1
1
0
1
cisco16-GRP
1
1
1
0
cisco17-GRP
1
1
1
1
Table 11
Default Boot Filenames (continued)
Action/File Name
Bit 3
Bit 2
Bit 1
Bit 0
Table 12
Configuration Register Settings for Broadcast Address Destination
Bit 14
Bit 10
Address (<net> <host>)
Off
Off
<ones> <ones>
Off
On
<zeros> <zeros>
On
On
<net> <zeros>
On Off
<net>
<ones>
Table 13
System Console Terminal Transmission Rate Settings
Baud
Bit 12
Bit 11
9600
0
0
4800
0
1
