Instruction manual
12.1 Overview of Power-Up Initialization Code
On powerup, the power-up initialization code is loaded from 8 KB of serial ROM
into the Icache of the CPU.
The initialization sequence is:
1. Perform any CPU-specific code.
2. Size the system memory.
3. Write the memory configuration to the bank configuration registers.
4. Find two good megabytes of memory, starting the search at the bottom of
memory.
• In 300 models, an error detected at this point is fatal. The power-up
sequence traps to the mini-console and the diagnostic LEDs display the
corresponding error number.
1
• In other models, the current lowest address bank is mapped out if an
error is detected. Memory is reconfigured and testing resumes. If all
banks have been mapped out, the code traps to the mini-console with
memory configured as 8 MB in banks 0 and 6, both mapped to start at
address 0.
1
5. Test the backup cache in the system. Map the backup cache to the good
memory found in the previous step. This allows isolation of any failures to
the backup cache.
6. Test the data path to the system FLASH ROMs. If the test fails, the power-up
code traps to the mini-console, and the LEDs display a number corresponding
to the fatal error.
1
7. Perform a checksum test on the system FLASH ROMs. If the test fails,
record it in the mailbox passed forward to the console code but proceed with
initialization.
8. Load the contents of the system FLASH ROMs into memory.
9. Perform a self-test on the TURBOchannel interface and COREIO ASICs.
Report errors detected to the SROM TT port; these errors are not considered
fatal; they are not recorded in the mailbox passed to the console, because the
console power-up diagnostics detect and report any of these errors.
10. Jump to the MACHINE_RESET PALcode function for the rest of the
initialization.
11. Decompress the system ROM code, which has been compressed by the build
procedure.
Chapter 14 discusses power-up initialization and firmware entry in greater detail.
1
The mini-console is for Digital use only.
Firmware: Overview 12–3