Compaq AlphaServer ES40, Service Manual

Page: 77 / 444

Power-Up Diagnostics and Display 3-9
SROM Power-Up Sequence
➊
When the system powers up, the SROM code is loaded into the I-cache
(instruction cache) on the first available CPU, which becomes the primary
CPU. The order of precedence is CPU0, CPU1, and so on. The primary
CPU attempts to access the PCI bus. If it cannot, either a hang or a failure
occurs, and this is the only message displayed.
➋
The primary CPU interrogates the I
2
C EEROM as stored in the DPR. The
primary CPU determines the optimum CPU and system configuration to
jump to.
The primary CPU next checks the SROM checksum to determine the
validity of the flash SROM sectors.
If flash SROM is invalid, the primary CPU reports the error and continues
the execution of the SROM code. Invalid flash SROM must be repro-
grammed.
If flash SROM is good, the primary CPU programs appropriate registers
with the values from the flash data and selects itself as the target CPU to
be loaded.
➌
The primary CPU (usually CPU0) initializes and then loads the flash
SROM code to the next CPU. That CPU then initializes the EV6 (21264
chip) and marks itself as a secondary CPU. Once the primary CPU sees
the secondary, it loads the flash SROM code to the next CPU until all
remaining CPUs are loaded.
➍
The flash SROM performs B-cache tests. For example, the ECC data test
verifies the detection logic for single- and double-bit errors.
➎
The primary CPU sizes memory and initiates all memory tests. The
memory is tested for address and data errors for the first 32 MB of
memory. It also initializes all the “sized” memory in the system.
If a memory failure occurs, an error is reported. An untested memory
array is assigned to address 0 and the failed memory array is deassigned.
The memory tests are re-run on the first 32 MB of memory. If all memory
fails, the “No Memory Available” message is reported and the system halts.
➏
If all memory passes, the primary CPU loads the console and transfers
control to it.