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Raven PCI Host Bridge & Multi-Processor Interrupt Controller Chip
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enabled, the MPC master will structure its bus request actions according to
the requirements of the FIFO. Caution should be exercised when using this
mode since the over-generosity of bus ownership to the MPC master can
be detrimental to the host CPU’s performance. The Bus Hog mode can be
controlled by the BHOG bit within the GCSR. The default state for BHOG
is disabled.
MPC Arbiter
The MPC Arbiter is an optional feature in the Raven, and is not used on the
MVME3600. Arbitration for the MPC bus on the MVME3600 is
performed external to the Raven.
MPC Bus Timer
The MPC bus timer allows the current bus master to recover from a lock-
up condition caused when no slave responds to the transfer request.
The time-out length of the bus timer is determined by the MBT field in the
Global Control/Status Register.
The bus timer starts ticking at the beginning of an address transfer (TS*
asserted), and if the address transfer is not terminated (AACK* asserted)
before the time-out period has passed, the Raven will assert the MATO bit
in the MPC Error Status Register, latch the MPC address in the MPC Error
Address Register, and then terminate the c cycle.
The MATO bit may be configured to generate an interrupt or a machine
check through the MEREN register.
The timer is disabled if the transfer is intended for PCI. PCI bound
transfers will be timed by the PCI master.
PCI Interface
The Raven PCI Interface is designed to connect directly to a PCI Local
Bus, and supports Master and Target transactions within Memory Space,
I/O Space, and Configuration Space.