These are the most basic data communications links, eg:
Historically, virtually all computers implement such data links,
using their serial ports. Key points:
The most common hardware interface standard used in such data
links is RS232: in fact, the term RS232
port is widely used as a synonym for serial
port. Typically, these ports are able to operate at a
range of "standard" bit rates between 300bps and 230400bps.
RS232 was orginally designed to interface a computer (or
DTE) to a modem (or
DCE), see later.
RS232 ports are almost an anachronism on modern computers,
although most manufacturers still provide them. More
modern, and versatile, alternatives include USB
and FireWire.
