The 3708 is a protocol converter that converts, among other things, a
terminal's ASCII character set to the host's EBCDIC character set. You
don't mention what terminal emulator is being used on the Apple IIGS, but
we suspect it is a VT52, VT100, or similar type of emulator.
Regardless, you'll need to verify that the terminal emulator type you
are using is among those supported by the 3708. Check the "IBM 3708 Planning
Manual" for the list of non-IBM ASCII display terminals it supports.
Even though terminal packages may not specifically state that they support
IBM host communications and PF keys, many emulators can send the specific
escape or command key sequences that are recognized and remapped by the
controller into PF keys. For instance, Apple Access II's key sequence
Esc-1 is remapped by many protocol converters to a PF1, an Esc-$ to PF16,
and so on.
When using a general-purpose terminal emulator, like a VT100 emulator, you
need to identify which ASCII key sequences map to PF keys, after you
satisfy the general connection requirements like handshaking issues. Check
the 3708 documentation for the ASCII to EBCDIC mapping. To determine if an
emulator will send the specific ASCII key sequences, check the emulator's
manual or contact the manufacturer. You too could use a datascope analyzer
to determine what the appropriate character combinations are.
In terms of general information, the 3708 Network Conversion Unit is a
ten-port, compact, desktop, protocol converter. It enables asynchronous
ASCII terminals or personal computers with asynchronous ASCII
communications capability to connect to and be compatible with one or
multiple SNA host and non-SNA host systems. The user of an asynchronous
ASCII terminal can access host applications that support 3270 displays and
printers, Network Terminal Option devices, and applications that support
the actual terminal type.