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2-30
Theory of Operation
Loader ROM
The SCM contains the bootstrap loader ROM which contains the code to "boot up" the operating
system from the system mass storage device. Figure 2-1 7 is a general flowchart of the loader ROM.
The address for the 8K loader ROM is stored in the same locations used by the RTC and NVM. The
starting address of the code is FFFF hex. The address is automatically decremented after each read.
Wait
r-~------l
I
Service Processor
I
I
~~~6u~~gffwhile
~-
: Keeping SELF TEST
I
L~~o~
_____
J
Initialize Service
Panel Output Module
and
Send I Am Here'Msg
To Service Processor
Send Initial
"Loader Here" Msg
To Each Output
Module
r---------,
--18K-Byte DMA
I
L _________
J
r - - - - -----,
--I
Display, etc
I
L _________ -.J
r--------..,
I
Service Processor
-1
Can Now Display
I Stack Fault Info
I
L _ _ _ _ _ _ _ _
-.J
is-;nd' AnyE;;o-;
Ms~
-,
I To All Output Modules
I
I
Will Not Return From
I
-i
Service Panel Output :
L . . - - - " " T " ' - - - - '
I
Module If Hard
tJi=~~~E~c::
__
J
r---------..,
I
Send Message
I
-;
To Each Output
I
~--""'T"----'
I
Module
I
L.. _ _ _ _ _ _ _ _ _ .J
r--------,
I
Will Not Return
I
I
From Service
I
I
Processor Output
I
I
Module
I
' - - - - T-----.J
I
I
r---
oL - - - . . ,
I
Service Processor
I
I
Will Turn Off
I
I
SELF TEST LED
I
I
While Keeping
I
I
LOAD LED On
I
L- _ _ _ _ _ _ _
....J
r----------,
I
OS Will
I
- -; Turn Off SELF TEST LED I
L-~~2.u~~~~N....:E~
J
Figure 2-17. Loader ROM Flowchart
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