Theory
91369 Service Manual 3-18
Boot Sequence Overview
When power is applied, the monitor begins its boot-up sequence. The following is a highly abbreviated version
of the sequence of events that occurs while the monitor is booting.
1 Program execution starts in Flash ROM.
2 Key internal and external devices and memories are mapped and enabled.
3 The boot-type value is read from Static RAM. This value is written to Static RAM, which is backed up by a
“SuperCap,” at every power-down or self-reboot. The value determines the kind of boot: warm or cold.
Warm booting maintains all data, then skips diagnostics and other steps in order to restore monitoring as
soon as possible.
4 Key areas of SDRAM are tested (cold boot only).
5 The boot code is copied from Flash ROM to SDRAM, where program execution resumes.
6 More internal and external devices are initialized.
7 Other key memory and CPU tests are performed (cold boot only).
8 Drivers needed for diagnostics and the boot console are installed.
9 Diagnostics are run (cold boot only).
10 Boot screen and the “3-2-1” countdown are displayed (cold boot only).
11 The VxWorks kernel and the application code are copied from Flash ROM to SDRAM, where program
execution continues.
12 The VxWorks kernel is started, and all internal and external devices are reinstalled and initialized.
13 The monitor application code is started, and normal monitor operation begins.
Normal Operation Overview
This is a high-level summary of what the software does as part of its normal operation.
Once the monitor is booted, it begins normal monitor operation. Normal operation can be viewed as several
high-level software and subsystem tasks running simultaneously. These interface to other tasks, and all the
tasks interface to hardware devices via device drivers.
Main Subsystems and Tasks
The SDLC subsystem sends packets from the modules to the rest of the system, including Ethernet and GDS,
and it also sends packets to modules.
The Interpreter subsystem provides modules and keys with “primitives” that they use, via table code, to create
and control their user interface on the monitor. The Keys subsystem handles touchscreen key presses. It
receives key presses from the user and notifies the keyboard interpreter, which then runs the appropriate table
code program. That program uses the key display task to redraw the new key state as feedback to the user.
The Global Data System (GDS) is the patient database with parameter data from the modules. It contains
current, general, trend, and waveform data.
To Next Page
Loading...