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Functional Description 4–3
21174 Core Logic Chip
4.2 21174 Core Logic Chip
The 21174 core logic chip provides a cost-competitive solution for designers using the
21164PC microprocessor to develop uniprocessor systems. The chip provides a
128-bit memory interface and a PCI I/O interface, and includes the 21174-CA chip
packaged in a 474-pin plastic ball grid array (PBGA).
Figure 4–2 shows the AlphaPC 164SX implementation of the 21174 core logic chip.
Figure 4–2 Main Memory Interface
4.2.1 21174 Chip Overview
The 21174 application-specific integrated circuit (ASIC) accepts addresses and com-
mands from the 21164PC microprocessor and drives the main memory array with the
address, control, and clock signals. It also provides an interface to the 64-bit PCI I/O
bus.
21164PC
data_h[127:0]
addr_h[39:4]
System Control
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DIMM 0
DIMM 1
DIMM 2
DIMM 3
Quick
Switches
21174
Buffers
memadr_[13:0]
mem_dat[128:0]
bnmemadr[13:0]
memwe_l
memcas_l[7:0]
memrasb_l[7:0]
memrasa_l[7:0]
miscellaneous
bnmemwe_l
bnmemcas_l[7:0]
bnmemrasb_l[7:0]
bnmemrasa_l[7:0]
bnmiscellaneous
be_l[0:2]
64-Bit PCI
I/O Bus
addr_bus_req_h
addr_cmd_par_h
cack_h
cmd_h[3:0]
dack_h
fill_h
fill_dirty_h
fill_error_h
fill_id_h
idle_bc_h
int4_valid_h[3:0]
sys_reset_l
tag_dirty_h
victim_pending_h
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