HP Data Entry and Forms Management System (VPLUS) Reference Manual (32209-90024)

634 AppendixK

SNA DHCF with VPLUS Applications

SNA DHCF Overview

SNA DHCF enables IBM System 370-compatible mainframes and series 900 HP 3000

systems to communicate interactively. Users of IBM 3270 display stations with access to

the IBM Host Command Facility (HCF) can access an HP 3000 in an SNA network and

initiate a session on the MPE XL operating system. SNA DHCF converts ASCII data from

HP 3000 VPLUS and TTY-compatible applications to the EBCDIC format that IBM 3270

display stations require, and vice versa.

To avoid potential confusion, it is important to note that IBM has a counterpart to

Hewlett-Packard's SNA DHCF, which is called DHCF.

System Connections

An IBM user can execute HCF commands to access an application on a remote IBM

minicomputer. If an IBM user wants to access an application on a remote HP 3000 instead,

he or she would use HCF and HP SNA DHCF, rather than IBM DHCF. HP SNA DHCF

emulates IBM DHCF, enabling the connection of an HP 3000 to an IBM mainframe. When

SNA DHCF is used, an HP 3000 perceives an IBM 3270 display station to be a virtual

terminal (VT) device. Conversely, an IBM mainframe perceives an HP 3000 to be a remote

IBM minicomputer.

VPLUS Supportability

SNA DHCF supports VPLUS applications if you recompile forms ﬁles for use with IBM

3270 display stations. Certain IBM 3270 display station limitations affect full-screen

VPLUS applications. For instance, the expanded HP terminal feature set offers display

enhancements, such as inverse video, that are unavailable on many IBM 3270 display

stations. Consequently, you cannot display these enhancements on an IBM 3270 display

station when using SNA DHCF.

Applications must exclusively use VPLUS intrinsics for all terminal I/O between

VOPENTERM and VCLOSETERM calls, because the SNA DHCF subsystem is in unedited mode

when performing VPLUS I/O. Unedited mode means that the subsystem expects valid

3270 data streams (in EBCDIC) from the VPLUS intrinsics.

If you design HP 3000 application programs with VPLUS-based forms for IBM 3270

application users, or for both HP 3000 and IBM 3270 users, it is imperative to note the

IBM 3270 display station and forms compilation limitations described in subsequent

sections of this appendix.