Chapter 1. VME/ISA Sync Board Overview

This chapter describes the VME and ISA Sync boards, including where and how they are typically used within a networking environment.

The VME and ISA Sync boards are similar in function and use, but are installed in either a VMEbus- or PC ISA bus-based system, respectively.

The VME Sync board uses a Motorola 68020 microprocessor to off-load the processing involved in controlling serial communications; the ISA Sync board uses a Motorola 68340 microprocessor.

The VME/ISA[1] Sync board is optimized for the front-end processing necessary for gateway communications and master-slave support functions.

Typical Use of the VME/ISA Sync Board

The VME Sync board is installed in the CHALLENGE L (deskside) and XL (rackmount) systems. The ISA Sync board is installed in the CHALLANGE M system.

The board and its software allow clusters of user terminals and printers connected to the host system to communicate in a data communications packet network environment by running protocols such as X.25 and SNA. As a communications link, the board connects with high-speed lines that are attached to other computers, modems, or other communications systems.

The VME/ISA Sync board and its software process data packets, such as those used in X.25 and SNA, and route them to and from other network nodes.

In the case of an X.25 WAN, the system containing the VME/ISA Sync board functions as data terminal equipment (DTE) in the X.25 network. It exchanges data with other network nodes, called data circuit-terminating equipment (DCE), which in turn route the data to other DTEs.

X.25 Communications

When the VME/ISA Sync board is configured to run in the X.25 network, it provides the following protocol standards:

  • The host system (CHALLENGE M, L, or XL, depending on the installed board) meets the X.29 and X.3 packet assembly/disassembly (PAD) standard.

  • Terminals connected to the host system meet the X.28 and X.3 PAD standard that allow them to run X.25.

  • Channels on the VME Sync board meet the EIA-232-C, V.35, or X.21 transmission standards.

  • Channels on the ISA Sync board meet the EIA-232-C transmission standard.

To run the X.25 protocol, the system must have the optional SX.25 product installed. For information on the SX.25 product, refer to the following documentation:

  • SX.25 Administrator's Guide describes how to configure and troubleshoot the SX.25 menu-driven software.

  • SX.25 User's Guide describes how to use the X.25 commands that allow you to connect to a host on a local area network (LAN) or wide area network (WAN).

SNA Communications

With the installation of the optional IRIS SNA products (IRIS SNA SERVER and IRIS SNA LU6.2) and the optional IRIS 3270 product, the VME/ISA Sync board can be configured to run in SNA networks and provide:

  • channels on the VME Sync board that meet the EIA-232-C, V.35, or X.21 transmission standards

  • channels on the ISA Sync board that meet the EIA-232-C transmission standard

  • IBM® Low Entry Networking (LEN) nodes with the IRIS SNA SERVER software

  • an application programming interface to IBM Advanced Program-to-Program Communication (APPC) protocol with the IRIS SNA LU6.2 software

  • 3270 sessions to IBM hosts using a variety of networking protocols including SNA with the IRIS 3270 software

Board Configuration Options

The VME/ISA Sync board comes in a variety of configurations, as described in this section.

The allowable configurations for the VME Sync board are:

  • One to four boards can be installed in the CHALLENGE L or XL systems for all electrical interfaces.

  • A board can support only one of the following types of electrical interfaces:

    • one to four channels (ports) running from 9.6 to 64 kilobytes per second (kbs) for EIA-232-C, V.35, or X.21 (default configuration)

    • two channels (ports) running at speeds from 64 kbs to T1 (1.54 Mb/second) for V.35 or X.21 (this configuration adds a mezzanine board)

Note: The VME Sync board must be installed and its hardware configured by a qualified Silicon Graphics system support engineer (SSE).

The configurations for the ISA Sync board are:

  • One board can be installed in the CHALLENGE M system.

  • The board supports a maximum of two EIA-232-C channels (ports) running at 56 kilobytes per second.

Make a note the following information for later use in creating the board configuration files, as described in Chapter 2, “Configuring Software for the VME/ISA Sync Board.”

  • number of VME/ISA Sync boards in your system

  • the board electrical interface type

  • number of channels on the board connected to leased lines

[1] Throughout this guide, references to “the VME/ISA Sync board” mean “the VME or ISA Sync board.”