Nortel Networks Circuit Card Benutzerhandbuch

 QPC841 Quad Serial Data Interface card

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 

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.