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After displaying the data in the received chain, the 3708 places the cursor in the
position next to the last character if NL does not follow. If the message is ended by
NL, the remainder of the line is set to nulls, and the cursor appears in the first
character position of the next line. This cursor position address is called the initial
cursor address and is stored to identify the starting position of the operator's display
input data.
SSCP Communications after an LU type 1 (NTO) BIND
The 3708 allows switching between the LV-LV session and the SSCP-LV sessions
for LV type
1
NTO operations as well. SSCP communication is initiated by
entering a system request simulation string from the terminal. This string may be
configured through the 3708 control terminal. The default value is 99999 (5 nines).
The system request simulation string can only be recognized when it is at the start of
a transmission, not in the middle.
The SSCP message is entered immediately after the system request simulation string.
The SSCP message may be up to 251 bytes long and must end with a defined line
turnaround character. The 3708 transmits this message to the SSCP and returns to
the LV-LV session. The 5-character string is deleted before the message is sent on
the SSCP-SLV session.
SSCP Communication to Printers
SSCP data sent to a printer, whether in LV type 1 or LV type 3 mode, is rejected by
the 3708 with a sense code of X '1007'.
SSCP Communication to Displays
When a user has put the display into SSCP mode by pressing the SYS REQ key
sequence, all data entered is sent to the host control program on the SSCP-SLV
session. The SSCP may also send data to the display in this mode.
Messages from the Host
The SSCP may send messages to a display when the SSCP-SLV session is in use.
The messages are byte strings consisting of SCS control codes and SSCP-supported
graphic codes. The only valid SCS control code is NL. Any other character in the
data is treated as a graphic character. The characters appearing on the screen for
code points other than supported graphics are unpredictable.
Each message from the SSCP is displayed at the current cursor location on the
screen. When the 3708 receives an NL in the SSCP data, it inserts nulls in the
character positions remaining in the display line being written, and positions the
cursor at the left most position of the next line, using a Set Cursor Address
sequence. Characters following the NL code are displayed beginning at the new
cursor position. The message wraps to the top of the screen if the last line on the
screen is written and additional characters remain in the data.
After displaying the data, the 3708 places the cursor in the position next to the last
character, or at the beginning of a line if the message ended with a NL. This cursor
position address is called the initial cursor address and is stored to identify the
starting position of the operator's input data.
3-50
IBM 3708
Description
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