The shift-out/shift-in (SO/SI) control characters are handled
slightly differently between the Asian HP terminal and the IBM Asian
display station. They are not used to enable and disable the DBCS
characters on HP terminals. Here is a description of the differences
when a user is inputting data and when data is displayed on the
user's terminal.
Differences During User Input of Data |
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Unlike the IBM PS/55 display station, HP terminals do not
update the screen with SO and SI control characters when the user
types DBCS data. Pass Thru does not process the DBCS data until
the user presses the [ENTER] key, because Pass Thru uses HP "block mode" terminal protocol,
where the terminal does not interrupt the HP 3000 after
each character is typed.
Pass Thru inserts SO and SI control characters around the
DBCS characters and performs DBCS syntax checking of all the DBCS
fields on the screen. If a field is already full, and Pass Thru
attempts to insert SO and SI control characters around the DBCS
characters, data overflow may occur, because Pass Thru has no room
to insert the additional SO and SI control characters. Pass Thru
will truncate data at the end of the field to make room for the
SO and SI characters. A warning message will be sent to the user's
terminal and will appear at the bottom of the screen.
Differences on User's Terminal Screen |
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Instead of displaying the SO and SI control characters directly
on the HP terminal, Pass Thru will map the SO and SI characters
to a single-byte blank and display them as blanks on the HP terminal screen.
