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2 • Theory of Operation
2.1 PMC423 Block Diagram
Figure 2-1 PMC423 Block Diagram
Signal
Conditioning
Port
1
2
3
This chapter provides information for local device connections, the bridge to the
host PCI, and the general systemʹs function. The design of the PMC423 is
illustrated in the block diagram that follows.
Host PCI
PCI/PCI Bridge
8 Port Serial
Signal
Conditioning
5
4
6
7
8
The PMC423 can operate with the 32‐bit 33/66MHz PCI bus, +3.3V or +5V PCI
signaling. This allows for the maximum flexibility for the different PCI bus
speeds, and signaling. The signaling level for the serial communication (RS232,
RS422, etc.) are configured via the software. The card generates the necessary
voltage for the serial signaling onboard using the +5V supply. This allows the
PMC423 to operate from the +3.3V and +5V supply only.
There are two eight port serial devices that are after the PCI to PCI bridge for a
total of sixteen ports. Due to the density of the serial ports, the hardware
handshake signals have not been routed to the front or the rear of the card.
L L
o o
c c
a a
l l
P P
C C
I I
B B
u u
s s
L
o
c
a
l
P
C
I
B
u
Port
s
8 Port Serial
Signal
Signal
Conditioning
Conditioning
12
9
10
11
13
14
Theory of Operation 17
16
15
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