Specifications
CHAPTER 4
Expansion Features
52 PCI Expansion Slot
PCI Expansion Slot 4
The Macintosh Performa 6400 computer uses the industry-standard peripheral
component interconnect (PCI) bus for an I/O expansion bus. The PCI bus is a 32-bit
multiplexed address and data bus. The PCI expansion slot has a 33.33 MHz system clock.
PCI I/O expansion cards are mounted horizontally in a 90-degree straight-through
adapter board, which is installed in the PCI expansion slot on the main logic board.
A total of 15 watts of power is provided for each of the PCI expansion slots. Both 5 volts
and 3.3 volts are supplied; the total power consumed by both voltages must not exceed
the 15-watts maximum.
The Macintosh Performa 6400 computer requires that PCI cards use the 5-volts signaling
standard described in the PCI Local Bus Specification, Revision 2.0.
The Macintosh Performa 6400 computer accepts standard 6.88-inch PCI cards as defined
by the PCI Local Bus Specification, Revision 2.0. The cards are required to use the standard
ISA fence described in the specification.
The PCI slots support all the required PCI signals and certain optional PCI signals. The
supported PCI signals are listed in Table 4-3.
Table 4-8 PCI signals
Signal name Description
AD[0–31] Address and data, multiplexed
C/BE[0–3] Bus command and byte enable signals, multiplexed
PAR Parity; used with AD and C/BE signals
FRAME# Cycle frame; asserted to indicate a bus transaction
TRDY# Target ready; selected device is able to complete the current phase
IRDY# Initiator ready; master device is able to complete the current phase
STOP# Stop; indicates the current target device is requesting the master to stop
the current transaction
DEVSEL# Device select; indicates that the driving device has decoded its address
as the target of the current access
IDSEL Initialization device select; used during configuration
REQ# Request; indicates to the arbiter that the asserting agent requires use of
the bus
GNT# Grant; indicates to the agent that access to the bus has been granted
CLK Clock; rising edge provides timing for all transactions
continued