DEC 4000 AXP Service Manual page 201

Table A–1 (Cont.) Environment Variables
# Variable
System-Dependent Environment Variables
tta*_baud
tta*_halts
version
Key to variable attributes:
NV - Nonvolatile. The last value saved by system software or set by console commands is preserved
across system initializations, cold bootstraps, and long power outages.
W - Warm nonvolatile. The last value set by system software is preserved across warm bootstraps
and restarts.
RO - Read-only. The variable cannot be modified by system software or console commands.
Attributes Function
NV Here ''*'' may be 0 or 1, corresponding to the
primary console serial port, tta0 or the auxiliary
console serial port, tta1. Specifies the baud rate
of the primary console serial port, tta0. Allowable
values are 600, 1200, 2400, 4800, 9600, and 19200.
The initial value for tta0 is read from the baud
rate select switch on the OCP.
NV Specifies halt characters recognized on the console
serial ports, tta0 and tta1. The value is an integer
bitmap, where:
bit 0—Enables (1) or disables (0) Ctrl/P to init
from the console.
bit 1—Enables (1) or disables (0) Ctrl/P halts
from the operating system.
bit 2—Enables (1) or disables (0)
BREAK/halts from the operating system.
Since tta1 is intended for modem support, this
bit is ignored on tta1 (BREAK/halts are not
permitted on the auxiliary port).
The default for tta0 is 2, enabling Ctrl/P halts
from the operating system. The default for tta1 is
0, disabling halts from the operating system.
RO Specifies the version of the console code in the
firmware. For instance, V2.3-2001 Aug 21 1992
14:25:19.
Environment Variables A–19