Intermec 6200 Reference Guide

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A queue is an 8Ćbyte variable for message passing between tasks.  A queue must

be initialized to empty by calling the queue initialization function.  A task can

perform three queue operations:  post, pend, and accept.
Posting is the action of adding a new message node to a queue.  A message node

consists of an 8Ćbyte field (manipulated by int15) followed by a message field.

The length and structure of the message field is left up to the user.  Queues differ

from mailboxes in that posting to a nonempty queue just adds a new node to the

tail of the queue.
When a task pends on an empty queue, the task is moved to the pended list until

another task posts to the queue.  When a task pends on a nonempty queue, the

pend request returns immediately without pending.
A task can accept from a queue if it wants to retrieve a message from the queue

without pending.  An accept from an empty queue returns 0.

The 4000 Series interrupts supported by 4000API.EXE are matrixed into the

entire set of interrupts.  These interrupts for 4000API.EXE with its symbolic

notation, 4000API, are listed in the Interrupt Definitions paragraph, starting on

page 6Ć30.  Also, see the Interrupt Index (in the Index section, at the end of this

publication) to locate interrupts alphabetically.  4000API.EXE supports

interrupts in the following table.  Remember 4000API can be configured (by the

use of certain switches) to ignore specific interrupts:

Table 6Ć2 

INT # 4000API Interrupts

Register Values

10h

Display Services
Video Screen Off/On, Alternative Settings

AH=12h BL=36h

Read/Write Contrast, Alternative Settings

AH=12h BL=FEh

Backlight Off/On, Alternative Settings

AH=12h BL=FFh

14h

Serial Communications Services
Initialize COM Port

AH=00h

Send a Character

AH=01h

Receive a Character

AH=02h

Get Port Status

AH=03h

Extended Initialize

AH=04h

Extended Port Control

AH=05h

Port Power Off/On

AH= FFh