In
IOSB ContentsRead Function, the offset
to terminator at IOSB+2 is the count of characters before the terminator
character (see
Read Function Terminators).
The terminator character is in the buffer at the offset specified
in IOSB+2. When the buffer is full, the offset at IOSB+2 is equal
to the requested buffer size. At the same time, IOSB+4 is equal
to 0. In the case of multiple character escape sequences that act
as terminators, the
terminator at IOSB+4 is the first character (ESC) of the escape
sequence. IOSB+6 contains the size of the terminator string, usually
1. However, in an escape sequence, IOSB+6 contains the size of the
validated escape sequence (see
Escape and Control Sequences). The sum of IOSB+2 and IOSB+6 is the number of
characters in the buffer.
Figure 14 IOSB Contents--Read Function
In
IOSB ContentsItemlist Read Function the terminator
position word contains a number, the character of which is determined
by the mode of operation. For itemlist read operations that do not
specify TRM$K_EM_RDVERIFY, this word contains the number of characters
from the end of the buffer to the cursor location at the time the
terminator character was received. If TRM$K_EM_RDVERIFY is specified,
the terminator position word contains the offset into the buffer
from the nonverified character.
Figure 15 IOSB Contents--Itemlist Read Function
The byte at IOSB+5 passes the status information, listed in
Byte IOSB+5 Status Information, on TRM$K_EM_RDVERIFY operations
in which TRM$M_TM_ARROWS or TRM$M_TM_TOGGLE is set in TRM$_MODIFIERS.
Table 31 Byte IOSB+5 Status Information
Bit
Interpretation
7 (sign bit)
0 to indicate rest of bits
valid. This applies to insert/overstrike and arrow key read verify
functionality only.
6-2
Always 0 if bit 7 is equal
to 0. Not used; reserved for future use.
1 TRM$V_ST_OTHERWAY
Set to indicate that read
is terminated in left-justify insert mode or right-justify overstrike
mode.
0 TRM$V_ST_FIELD_FULL
Read terminated on an autotab field full
condition. IOSB+7 contains an index to the cursor.
In
IOSB ContentsWrite Function, the remote
terminal driver does not return the number of lines output or the
cursor position.
Figure 17 IOSB Contents--Set Mode, Set Characteristics,
Sense Mode, and Sense Characteristics Functions
When an application program makes an I/O request for a connection
to a remote device on a terminal server, the LAT port driver places
status information about the request into the first word of the
I/O status block, as shown in
IOSB ContentsLAT Port Driver Function.
IO$M_LT_CONNECT Request Status lists
the possible status returns.
If the server rejects the request, the LAT port driver returns
a numeric LAT rejection code in the second word of the I/O status
block.
LAT Rejection Codes lists
the LAT rejection codes.
HP OpenVMS I/O User's Reference Manual
Terminal Driver
