HP 330 Service Information Manual page 150

5. Check for video electronics:
A check is done for the ID register of a HP 98546A card set. A bit is set to indicate its
presence. Then the Boot ROM looks for a bit mapped video boards by checking location
56000016 for a primary DIO ID of 25 and a secondary ID of 1. If the proper ID is found,
then a bit is set to to indicate the presence of a bit-mapped video board.
6. Determine if Internal HP-IB is Present:
Channel zero of the system interface board is armed.
7. Determine Which, if any, Alpha video card is Present:
A register is set to the location of the top RAM test routine. Note that only video boards
with an ID register are supported.
8. Initialize and Blank Alpha Display Controller, if present:
If an HP 98546A card set is present, then it will be initialized and blanked.
9. Top RAM Test:
A nlemory test is executed on just enough RAM to allow the rest of the Boot ROM code
to operate. (A "fatal error" will occur when there is not enough RAM.) If there is a
memory failure, 8416 will be displayed on the self-test LEDs. If memory is missing, 4416
will be displayed on the self-test LEDs. If an alpha display controller is present, the Boot
ROM will also write one of these messages:
RAM FAILED ABOVE FFFFCOOO
RAM GONE ABOVE FFFFCOOO
for memory failure and memory missing, respectively. These messages will not be dis-
played on a monitor through a bit-mapped video board.
NOTE
If high RAM fails or is missing, then the test LEDs and beeper will
give the only notification on a system with a bit-mapped video board
or remote console.
NOTE
The functions in the next section depend upon a working RAM stack.
As in the previous steps, the LEDs are set to a new value before each
step.
134
Boot ROM Functions