Nortel Networks Circuit Card - Manual (Page 872)

Page 872 of 906 QPC841 Quad Serial Data Interface card
553-3001-211 Standard 3.00 August 2005
Functional description
The QPC841 Quad Serial Data Interface card contains all the logic for four
asynchronous serial ports, including the baud rate generators. These serial
ports are directly accessed by the system processor using memory reads and
writes.
The QPC841 Quad Serial Data Interface card contains four universal
asynchronous receiver/transmitters (UARTs) and the logic necessary to
connect the UARTs to the system processor bus. See Figure 188 on
page 873 .
The other logic on the card consists of four baud rate generators, four
RS-232-C driver/receiver pairs, and the jumpers and logic needed to
configure the UARTs.
The address select switches and logic on the card always address the UARTs
using two pairs of addresses: 0 and 1, and 2 and 3 through 15 and 16. The
pairs do not need to be consecutive. Other switches on the board determine
the baud rate for each individual port and whether the port is configured to
talk to a terminal (DTE equipment) or a modem (DCE equipment).
Instructions for setting the jumpers are given later in this section.