HPC3130A
PCI HOT PLUG CONTROLLER
SCPS055 – NOVEMBER 1999
64-bit implementation
When inserted into a slot, a 64-bit PCI card tests whether that slot is 64-bit or 32-bit. If REQ64 is low when
PCI_RST is deasserted, that signals the card that the slot is 64-bit; otherwise, the slot is 32-bit. The HPC3130A
providesamechanismtonotifythePCIcarditisconnectedtoa64-bitPCIslot. ThemechanismusesREQ64ON
and REQ64ON as CBT switch enables and SLOTREQ64 as the slot specific REQ64 signal. As depicted in
figures 12 and 13, REQ64ON enables the CBT switch that routes SLOTREQ64 to the slot, and REQ64ON
enables the CBT switch that routes SYSTEMREQ64 to the slot. SYSTEMREQ64 will always be routed to the
slot except when the slot is disconnected from the bus or during a connection sequence. It is very important
during a connection sequence that the software clears bit 3 in the hot plug control register to drive SLOTREQ64
low. The HPC3130A will deassert SLOTREQ64 during the automatic connection sequence.
In a 32-bit PCI bus implementation, the SLOTREQ64, REQ64ON, and REQ64ON outputs are not connected.
BUSON
HPC_PCI
System PCI Bus
REQ64ON
PCI
SLOT
SYSTEMREQ64
REQ64ON
SLOTREQ64
CBT3306
Figure 12. SLOTREQ64 Implementation Using CBT3306
BUSON
HPC_PCI
System PCI Bus
SYSTEMREQ64
SLOTREQ64
PCI
SLOT
S
OE
CBT3257
REQ64ON
Figure 13. SLOTREQ64 Implementation Using CBT3257
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