HP 3000 Manuals HP 3000 Manuals
SNA DHCF/XL Overview SNA DHCF/XL 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/XL 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 confusion, it is important to note that IBM has a counterpart to Hewlett-Packard's SNA DHCF/XL, 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/XL, rather than IBM DHCF. HP SNA DHCF/XL emulates IBM DHCF, enabling the connection of an HP 3000 to an IBM mainframe. When SNA DHCF/XL 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/XL supports VPLUS applications if you recompile forms files for use with IBM 3270 display stations. Certain IBM 3270 display station limitations affect VPLUS applications. For instance, the HP terminal feature set offers display enhancements, such as inverse video, that are not available on many IBM 3270 display stations. Consequently, you cannot display these enhancements on an IBM 3270 display station when using SNA DHCF/XL. Applications must exclusively use VPLUS intrinsics for all terminal I/O between VOPENTERM and VCLOSETERM calls, because the SNA DHCF/XL subsystem is in unedited mode when performing VPLUS I/O. In unedited mode, the subsystem expects valid IBM 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 chapter.