Specifications

Data Structures
1.19 Unit Control Block (UCB)
Table 1–26 (Cont.) UCB Terminal Extension
Field Name Contents
TTY$V_PC_XOFAVL Auto XOFF supported. If set, auto XOFF is
supported for this port.
TTY$V_PC_XOFENA Auto XOFF enabled. If set, auto XOFF is
currently enabled on this port.
TTY$V_PC_NOCRLF No auto line feed. If set, a line feed is not
generated following a carriage return.
TTY$V_PC_BREAK Break. If set, the port driver should generate
break character; if clear, the port should turn
off the break feature.
TTY$V_PC_PORTFDT FDT routine. If set, the port driver contains
FDT routines.
TTY$V_PC_NOMODEM No modem. If set, the port cannot support
modem operations.
TTY$V_PC_
NODISCONNECT
No disconnect. If set, the device cannot support
virtual terminal operations.
TTY$V_PC_SMART_
READ
Smart read. If set, the port contains additional
read capabilities.
TTY$V_PC_
ACCPORNAM
Access port name. If set, the port supports an
access port name.
TTY$V_PC_
MULTISESSION
Multisession terminal. If set, the port is part of
a multisession terminal.
UCB$B_TT_DS_RCV Current receive modem.
UCB$B_TT_DS_TX Current transmit modem.
UCB$W_TT_DS_ST* Current modem state.
UCB$W_TT_DS_TIM* Current modem timeout.
UCB$B_TT_MAINT* Maintenance functions. This field is used as the argument to the port
driver’s PORT_MAINT routine. It is written by the class driver and read by
the port driver.
It contains several bits that allow the following maintenance functions:
IO$M_LOOP Set loopback mode.
IO$M_UNLOOP Reset loopback mode.
IO$M_AUTXOF_ENA Enable the use of auto XON/XOFF on this line.
This is the default.
IO$M_AUTXOF_DIS Disable the use of auto XON/XOFF on this line.
IO$M_LINE_OFF Disable interrupts on this line.
IO$M_LINE_ON Reenable interrupts on this line.
Reference these bits by using the mask, shifted as follows:
BITB #IO$M_LOOP@-
7,UCB$B_TT_MAINT(R5) ;Set loopback mode
UCB$B_TT_MAINT also defines the bit UCB$V_TT_DSBL that, when set,
indicates that the line has been disabled.
UCB$B_OLD* The full name of this field is UCB$B_TT_OLDCPZORG; it currently serves
as a filler byte.
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