IBM RS/6000 7024 E Series, Service Manual

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Chapter 6. Firmware
The firmware is organized into three major sections:
Ÿ
Boot Block: Receives control at power on, and is able to perform a soft
firmware recovery from diskette when necessary.
Ÿ
Firmware Core: Brings the system up to where the compressed image has
been decompressed into memory and running.
Ÿ
Virtual Disk: Contains the firmware modules required to support each hardware
subsystem.
Boot Block
Ÿ
Power-On the system, the power LED begins to glow on the front panel.
Ÿ
Hardware passes control to storage address 0xFFF00100, the firmware entry
point.
Processor POST
Ÿ
An uncompressed instruction -- "Branch to the System Environment" resides at
address 0xFFF00100. This will test that "Branch" works. If it fails, then the next
instruction is executed(which is data). A program check interrupt occurs, where
another branch is encountered followed by a program check. The system has
essentially come to a STOP, with no signs of life (no beep, no hard file LED).
Ÿ
At the branch target address -- initialize the 60X Processor Registers.
Ÿ
If the 60X fails, the code will STOP by performing a Branch to itself instruction.
The system will appear to be doing nothing; but cooling fans might be observed
running.
Setup the Firmware Environment
Prepare for the compressed image of the firmware to be uncompressed and run from
memory by doing the following:
1. Initialize the memory controller; find a small amount of good memory.
2. When no memory to configure then turn on the hard file LED and STOP.
3. Setup the C Environment in the small amount of good memory.
4. Everything is going OK so give One Short Beep on the speaker.
5. Check CRC of the compressed firmware.
Chapter 6. Firmware
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