Hardware Reference
In-Depth Information
Table 14.13 Connections for a 9-Pin-to-25-Pin Serial Adapter
The UART Chip
The heart of any serial port is the Universal Asynchronous Receiver/Transmitter (UART)
chip. This chip controls the process of breaking the native parallel data within the PC into
serial format and later converting serial data back into the parallel format. Recent PCs
with serial ports integrated into the motherboard chipset emulate the functionality of the
UART.
Serial Port Configuration
Each time a serial port receives a character, it has to get the attention of the computer by
raising an IRQ line. Eight-bit ISA bus systems have eight of these lines, and systems with
