IBM 3708 Description page 187

Byte 1 is a count of the number of characters in the desired outbound control
sequence. If the count is 0, the function is undefined for this terminal type.
(Highlighting and colors, for example, are not provided by all terminals.)
Subsequent bytes contain the characters to be sent to the terminals for the desired
function. For example, to cause the 3101 screen to be cleared, the sequence ESC L
must be sent to the device. Therefore, the entry in the table for the CLEAR
SCREEN function is 02
1B
4C 00 00 00 (since the count is 2, the last 3 bytes of this
entry are unused).
Special considerations for the terminal control section are the following:
• SET CURSOR ADDRESS is unique in that it contains variable fields. The
usual sequence for this function is ESC
X R C,
where
X
is some fixed character,
and Rand C are the line and column at which the cursor is to be positioned.
This is represented in the terminal table as a 2-byte sequence, ESC X. The 3708
supplies the line and column values.
• ACTIVATE STATUS LINE is provided for a terminal that has an addressable
status line, but which requires a special sequence that tells the terminal to expect
the 3708 to send START STATUS and STOP STATUS. However, ACTIVATE
STATUS LINE, if defined in the table, is sent to the terminal by the 3708 when
beginning a protocol conversion session, regardless of the setting of the
addressable status line flag in byte 2 of the terminal table. (This is the only time
that ACTIVATE STATUS LINE is sent.) This allows ACTIVATE STATUS
LINE to contain any terminal initialization sequence that may be useful.
• If the status line flag in the terminal table is 1 but the count field of the START
STATUS sequence is 0, the 3708 uses normal SET CURSOR ADDRESS
commands to position the cursor to write the status line. For example, if the
terminal is operating in 3270 Model 2 mode (24 x 80), the 3708 sends a SET
CURSOR ADDRESS sequence for row 25, column
1
to position the status line
data.
• The format of the two highlight sequences and of the four color sequences must
all be the same relative to the Terminal Field Attribute Byte or Non-Field
Attribute Byte. Consult the reference manual for the terminal to determine
which, if any, of the terminal visual attributes use a Field Attribute Byte.
• To match the basic four-color support of the 3270 data stream, colors 1, 2, 3,
and 4 should be green, red, blue, and white, respectively. However, for a
user-defined terminal, you can use any four colors that you prefer. All four
colors must be filled in with correct sequences. Colors can be duplicated.
• If you are using highlighting, you must define both the highlight ON and
highlight OFF sequences.
• ANSI visual attribute support, other than highlighting on/off, can require
control sequences longer than the 5-character sequence that can be explicitly
specified in the Terminal Control section. To allow additional flexibility in
defining visual attributes, the 3708 provides a method for defining longer ANSI
highlighting sequences. This method should be applied only to the highlighting
on/off and color 1, 2, 3, and 4 fields of the TUT definition. However, the 3708
supports this method for all sequences from addresses X'OOOOA6' to X'000117',
except SET CURSOR ADDRESS.
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IBM
3708 Description