for all layers These functions include TEI negotiation with

the network management entity and the handling of unre-

coverable errors This task implements as much of the man-

agement entity as is currently defined and in addition what-

ever is necessary for the operation of the other tasks

157 Tracer Task

The Tracer Task serves two purposes to demonstrate the

lower ISDN layers via a menu-driven telephone emulation

mode and to trace system mail message traffic

158 Task

View Task Exerciser and Debugger

Task

View is a special-purpose task that can be inserted

into the multi-tasking Executive environment in place of the

Tracer Task It reads and interprets a user supplied ASCII

scenario file Under control of this senario file Task

View

sends mail messages to a specified mailbox (or mailboxes)

where they are read by the task under test Mail messages

sent by the task under test in response to this input are then

displayed by Task

View In this way the task may be exer-

cised and debugged

20 Functional Description

21 INTRODUCTION

This description defines the functional requirements of the

ISDN Basic Rate Interface Software Package implemented

on the National Semiconductor HPC Microcontroller Family

Specifically the HPC16400 Software Package implements

or supports the following high-level functions

point

The HPC ISDN Software Package has been divided into

several functional software elements as illustrated in the

HPC ISDN Functional Block Diagram

Figure 21 These

functional elements correspond to software modules The

purpose of this section is to introduce the various software

elements to define their interactions and to relate their

functionality to the appropriate ISDN standards where ap-

plicable

The HPC ISDN Software Package will require additional

software drivers and application-specific tasks prior to serv-

ing as a useful ISDN Terminal Endpoint (TE) entity The

HPC ISDN software has been coded and documented to

allow easy integration of additional application code

The HPC ISDN Software elements illustrated in

Figure 21

have been divided into the following categories

(22)

(23)

(24)

(25)

(26)

The HPC Executive contains software elements that are

necessary for HPC ISDN Applications These elements in-

clude a Multi-Tasking Scheduler a Memory Manager a Tim-

er Manager and a Mail Manager The HPC Executive soft-

ware elements are tightly coupled and streamlined for the

National Semiconductor HPC family of controllers

The IO Device Drivers interface the HPC hardware ele-

ments to the HPC ISDN Software The Layer 1 Driver imple-

ments the ISDN PHYSICAL Layer 1 requirements for the

HPC ISDN system The Layer 2 Driver interfaces the HPC

DMAHDLC controller channels to the Layer 2 Link Access

Task Scheduler

TLDD10077 – 3

FIGURE 21 HPC ISDN Software Functional Block Diagram

4