Specifications

4–22 Functional Description
Subject to Change – 17 January 1997
DC Power Distribution
Figure 4–9 Serial ROM
4.9 DC Power Distribution
The AlphaPC 164 derives its system power from a user-supplied PC power supply.
The power supply must provide +12 V dc and -12 V dc, -5 V dc, +3 V dc, and
+5 V dc (Vdd). The dc power is supplied through power connector J3 (pc164.31).
(See Figure 4–10.) Power is distributed to the board logic through dedicated power
planes within the 8-layer board structure.
As shown in Figure 4–10, the +12 V dc, -12 V dc, and -5 V dc are supplied to ISA
connectors J33 and J35 (pc164.23). The +12 V dc and -12 V dc are supplied to ISA
connectors and PCI32 connectors J19 and J20 (pc164.20). The +12 V dc is also
supplied to the CPU fan connector J21 (pc164.28), auxiliary fan connectors J2 and
J22 (pc164.28), and to the flash ROM write-enable connector J31 (pc164.28). Vdd
(+5.0 V) is supplied to ISA connectors, PCI32 connectors, and most of the board’s
integrated circuits. Vdd also drives the +2.5-V regulator, which supplies the 21164
microprocessor.
srom_dat_h
srom_oe_l
srom_clk_h
srom_clk_l
test_srom_d_l
J32
pc164.3
pc164.26
21164
pc164.2
SROM
pc164.3
2
5
test_srom_d
eb164.3 PC164-09
real_srom_d
MUX