User's Manual

PMAC2 PCI Hardware Reference Manual
Hardware Setup 3
HARDWARE SETUP
Piggyback CPU Board Jumper Configuration
Watchdog Timer Jumper
Jumper E1 on the Turbo CPU board must be OFF for the watchdog timer to operate. This is an important
safety feature, so it is vital that this jumper be OFF in normal operation. E1 should be put ON only to
debug problems with the watchdog timer circuit.
Dual-ported RAM Source Jumper
Jumper E2 must connect pins 1 and 2 to access dual-ported RAM from the baseboard. To use Option 2
DPRAM on the baseboard, jumper E2 must be in this setting.
Jumper E2 must connect pins 2 and 3 to access dual-ported RAM through the JEXP expansion port. To
use DPRAM on an external accessory board, jumper E2 must be in this setting.
Power-Up State Jumpers
Jumper E4 on the Turbo CPU board must be OFF, jumper E5 must be ON, and jumper E6 must be ON, in
order for the CPU to copy the firmware from flash memory into active RAM on power-up/reset. This is
necessary for normal operation of the card. (Other settings are for factory use only.)
Firmware Load Jumper
If jumper E7 on the CPU board is ON during power-up/reset, the board comes up in bootstrap mode,
which permits the loading of new firmware into the flash-memory IC on the board. When the PMAC
Executive program tries to establish communications with a board in this mode, it will detect
automatically that the board is in bootstrap mode and ask what file to download as the new firmware.
Jumper E7 must be OFF during power-up/reset for the board to come up in normal operational mode.
Flash Memory Bank Select Jumpers
The flash-memory IC in location U10 on the Flex CPU board has the capacity for eight separate banks of
firmware, only one of which can be used at any given time. The eight combinations of settings for
jumpers E10A, E10B, and E10C select which bank of the flash memory is used. In the factory production
process, firmware is loaded only into Bank 0, which is selected by having all of these jumpers OFF.
Base Board Jumper Configuration
Servo and Phase Clock Direction Control
Jumper E1 should be off if the board is using its own internally generated phase and servo clock signals.
In this case, these signals are output on spare pins on the J5A RS-422 serial-port connector, where they
can be used by other PMAC controllers set up to take external phase and servo clock signals.
Jumper E1 should be on if the board is using externally generated phase and servo clock signals brought
in on the J5A RS-422 serial port connector. In this case, another PMAC controller generates the clock
signals and output is on its serial port connector. Commonly, serial communications are also shared over
a multi-drop RS-422 cable, with software addressing of the cards matching the I0 serial card number for
each controller. Alternately, the phase and servo clock signals can come from clock signals involved in
the process.
If E1 is on for external phase and clock signals, and these clock signals are not brought in on the serial
port connector, the watchdog timer will trip immediately and shut down the board.