OEM Boards and Systems Hanbook 1989 - Al Kossow's Bitsavers

FEATIlRES
1lEA£.'I'IIWE stJIiTWtlaE I'IlOM 'I'HE
INIJIJS'I'Il1' u;,.t.a
Intel has been the industry leader in microprocessor·based
real-time computing since It Invented the microprocessor. 1\0
other company supplies the range of real·tlme solutions that
we do. Since 1977. thousands of customers have used our
iRMX. real-time operating systems. "
Now Intel has put Its real·time expertise into a 32·bit kernel
that supports the 80386 microprocessor and the 80376
embedded controller. TIle IRMK Version 1.2 Kernel saves you
the cost of designing. debugging. and maintaining your own
executive for real·t1me systems. You can concentrate on
writing your application rather than on writing a kernel.
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lUNGE fJI' IrEtI£.'I'IIWE tI,.,.UCtl'l'IONS
The IRMK Kernel's high performance and rich set of real·
time services make it ideal for a wide range or real·time
"applications. including:
Data acquisition and analysis
Continuous process control
Discrete process control
. Simulation
Medical instruments
Test instrumentation
Image processing
Automated test
AvioniCS and navigation
Field command control
Energy and environmental control
Radio control
Slitellite communications
Terminals
Graphics work stations
Robotics
Signal processing
Laser printers
Front-end concentrators
Host communications
tI alt:H SE'I' OF aEtI£.'I'IME SEanCES
The iRMK Version 1.2 Kernel provides a rich set of services
for real·time applications. Including:
• Task management with system calls to create. manage.
and 'schedule tasles in a multitasking environment. The
Kernel offers pre-emptive priority scheduling combined
with optional time-slice (round robin) scheduling.
The scheduling algorithm used by the iRMK Kernel allows
tasks to be rescheduled in a fixed amount of time .
regardless of the number of tasks. Applications may
contain any number of tasles.
An application can provide optional task handlers to
customize task management. These handlers can execute
"on task c",ation. task SWitch. task deletion. and task
priority change. Task handlers can be used for a Wide
range of functions including saving and restoring the
state of coproct'Ssor registers on task switch. masking
intt>rrupts baSt'll on task priority. or implementing
statistical and diagnostic monitors.
• Interrupt management by immediately switching control
to user·written interrupt handlers when an interrupt
occurs. Response to interrupts is both fast and
predict.able. Most of the Kernel's system calls can be
executed directly from interrupt handlers.
• Time managl'mcnt providing single·shot alarms. repetitive
alarms. and a real·time clock. Alarms can be reset.
These time manageml~nt facilities can solve a wide range
of real·timl' programming problems. Single·shot alarms.
for example. can bl' used to handle timeouts. If the
timeout occurs. till' alarm invokt'S a user-written handler:
if the event oCl~Urs befort' tht' timeout. the application
simply delrtes the alarm. Other uses for the Kernel's time
management facilities include polling devices with
repetitive alarms. putting tasks to sleep for specified
periods (If time. 01' implementing a time-of-day clock .
• Semaphores. rt'~itlns. anti mailboxes for intertask
synchronization and t~lmmunication. Semaphores are
used for intertasle Signalling and synchronization. Regions
are special binary semaphores used to ensure mutual
exclusion and prevent dradlock when tasks contend for
control of system resources. A task holding a region'S
unit runs at the priority of the highest priority task
waiting for the rt'glnn's unit.
Mailboxes are queues that can hold any number of
messages and are used to exchange data between tasks.
Either data or pointers ran be scnt using mailboxes. The
Kernel allows mailbox messages to be of any length. High
" priority messages can be placed (jammed) at the front of
the message queue to ensure that they are received
before other messages queued at the mailbox.
To ensure that high priority tasks are not blocked by
lower priority t.asks, the Kernel allows ~sks to queue at
semaphores and mailboxes in priority order. The Kernel
also supports first·in. first·out tasle queuing.
• Memory pool manager that provides fixed and variable
block allocation. Memory can be divided into any number
of pools. Multiple memory pools might be created for
different speed memories or for allocating different size
blocks. Access to a memory pool for fixed,sized allocation
is always deterministic.
The Kernel·supplied memory manager works with flat.
segmented. and paged addressing. Users can write their
own memory manager to provide different memory
management policies or to support virtual memory.
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