SNA IMF supports SNA Character String (SCS)
control codes, allowing programs on the HP 3000 to emulate LU.T1
(SCS mode) printers. SNA IMF also supports the 3270 data stream,
so HP programs can also emulate LU.T3 (3270 mode) printers. Only
one mode can be active at a time.
If your program is emulating an LU.T1 printer, it must be
in transparent mode. The data stream, with SCS codes, is passed untranslated
into the internal screen image. Your program is responsible for
interpreting the SCS codes.
The SCS data stream has fifty-six control codes. The IBM 3287
printer supports 18 of the SCS control codes, and HP printers support
17 of those 18 control codes. The Set Attribute (SA) SCS control
code is the only code supported by the IBM 3287 that HP printers
do not support. The SA control code is an extension of the SCS data
stream and is considered an option by IBM. Also considered optional
SCS extensions are the Structured Field and Attribute Processing
(SFAP)
An LU.T1 session can support only a screen image of 3870 bytes
and an RU size of 3584 bytes. If you exceed this RU limit, the screen
image will be overwritten.
For a complete description of the 17 supported SCS codes,
refer to the IBM 3287 Printer Models 1 and 2 Component
Description (IBM P/N GA26-3153).
As with the IBM 3287 printer, you must physically align paper
forms at the first line to be printed when you insert forms into
the printer. This action will ensure correct feeding of the forms.
Also, any change in format (SHF, SLD, SVF) must be followed by the
appropriate synchronizing function (CR, NL, FF) in order to maintain
format integrity.
Table B-1 “SCS Codes Supported by SNA IMF” lists the SCS codes supported
by SNA IMF.
