User`s guide

Figure 3–14 SROM Serial Port
LJ04142A.AI
SROM
real_srom_d
IRQMUX
J2
srom_clk_l
gnd
test_srom_d_l
21064A
AlphaPC64.34
test_srom_d
srom_oe_l
AlphaPC64.3
srom_oe_l
srom_clk
srom_d
AlphaPC64.2
AlphaPC64.3
After the SROM code has been read into the Icache, the 21064A SROM port
can be used as a software controlled serial port. The serial port can be used for
such things as diagnosing system problems when the only working devices are
the 21064A, the SROM, and the logic required for their direct support.
3.11 dc Power Distribution
The AlphaPC64 derives its system power from a user-supplied, industry-
standard PC power supply. The power supply must provide +12 V dc, –12 V dc,
–5 V dc, Vdd (+5 V dc), and 3.3 V dc. The dc power is supplied through power
connectors J27, J28, J29, and J31 (AlphaPC64.38) (see Figure 3–15). Power
is distributed to the board logic through dedicated power planes within the
6-layer board structure.
As shown in Figure 3–15, the +12 V dc, –12 V dc, and –5 V dc are supplied to
ISA connectors J17, J18, and J19 (AlphaPC64.27).
The +12 V dc and –12 V dc are supplied to PCI connectors J20, J21, J22, and
J23 (AlphaPC64.24–25).
The +12 V dc is also supplied to the CPU fan connector J13 (AlphaPC64.38)
and enclosure fan connector J1 (AlphaPC64.38).
Vdd is supplied to ISA connectors J17, J18, and J19 and PCI connectors J20,
J21, J22, and J23.
Functional Description 3–39