SECTION 6
Conversions and Interfaces
6-22 PEN*KEY
R
6100 Computer Programmer’s Reference Guide
Mailboxes
A mailbox is a 4Ćbyte variable used for messageĆpassing between tasks. A mailĆ
box is empty if it contains 0; otherwise, it contains a message. A task can perĆ
form three mailbox operations: post, pend, and accept.
Posting is the action of placing a 4Ćbyte message into a mailbox. Posting to a
mailbox that is not empty overlays the message that was in the mailbox.
When a task pends on an empty mailbox, the task is moved to the pended list
until another task posts a message to the mailbox. When a task pends on a
mailbox with a message in it, the pend request returns without pending.
A task can accept from a mailbox if it wants to retrieve a message from the box
without pending. An accept from an empty box returns zero.
Queues
A queue is an 8Ćbyte variable for messages passing between tasks. A queue
must be initialized to empty by calling the queue init function. A task can perĆ
form 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 INT 15) followed by a message field.
The length and structure of the message field is 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 zero.
INT 15h: Intermec Miscellaneous System Services
These services consist of the following topics:
"
Accumulating and computing the CRC on specified blocks of data
"
Receiving, sending, and exchanging network packets
"
Adjusting the processor speed
"
Beeping the buzzer
"
Returning a pointer to the BIOS version
INT 15h: PC-Like Miscellaneous System Services
These services consist of the following topics:
"
Requesting system shutdown
"
Translating keyboard scan codes
"
Pending until a key is pressed on the keyboard
INT 16h: Keyboard Services
These services consist of the following topics:
"
Set Typematic Rates
"
Turn the key repeat on and off
"
Setting the key repeat
"
Turn the keyclick on and off
"
Swapping the keyboard translate tables
6. Conversions and
Interfaces
Содержание PEN*KEY 6100
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Страница 22: ...Preface 8 PEN KEYR 6100 Computer Programmer s Reference Guide PREFACE ...
Страница 112: ...SECTION 4 Power Management 4 10 PEN KEYR 6100 Computer Programmer s Reference Guide 4 Power Management ...
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