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Figure 3–3 AlphaPC 164UX PCI Bus Devices
82371SB
SIO Bridge
pc164ux.28
ISA Bus
53C875
SCSI
Controller
pc164ux.24
The PCI bus supports multiplexed, burst mode, read and write transfers. It sup-
ports synchronous operation of 33 MHz. It also supports either a 32-bit or 64-bit
data path with 32-bit device support in the 64-bit configuration. Depending upon
the configuration and operating frequencies, the PCI bus supports up to 264-MB/s
(33 MHz, 64-bit) peak throughput. The PCI provides parity on address and data
cycles. Three physical address spaces are supported:
•
32-bit memory space
•
32-bit I/O space
•
256-byte-per-agent configuration space
Digital Semiconductor 21174 Core Logic Chip
21174
pc164ux.8-10
Primary PCI Bus
21052
21143
PCI to PCI
Ethernet
Controller
Bridge
pc164ux.26
pc164ux.19
Secondary PCI Bus
PCI32
PCI32
PCI32
PCI32
Slot 1
Slot 0
Slot 2
Slot 3
J6
J7
J5
J21
PCI64
Slot 0
J2
Bus
Device
21052
SIO Bridge
Primary
21143
64 Slot 0
32 Slot 0
32 Slot 1
32 Slot 2
Secondary
PCI32
32 Slot 3
Slot 4
32 Slot 4
J22
53C875
Functional Description
IDSEL Select
p64_ad24
p64_ad25
p64_ad26
p64_ad28
p32_ad24
p32_ad25
p32_ad26
p32_ad27
p32_ad28
p32_ad29
3–5
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