82C50A pdf datasheet (CMOS Asy

The 82C50A Asynchronous Communication Element
(ACE) is a high performance programmable Universal
Asynchronous Receiver/Transmitter (UART) and Baud
Rate Generator (BRG) on a single chip. Using Intersil’s
advanced Scaled SAJI IV CMOS Process, the ACE will
support data rates from DC to 625K baud (0-10MHz clock).
The ACE’s receiver circuitry converts start, data, stop, and
parity bits into a parallel data word. The transmitter circuitry
converts a parallel data word into serial form and appends
the start, parity, and stop bits. The word length is
programmable to 5, 6, 7, or 8 data bits. Stop bit selection
provides a choice of 1,1.5, or 2 stop bits.
The Baud Rate Generator divides the clock by a divisor
programmable from 1 to 216-1 to provide standard RS-
232C baud rates when using any one of three industry
standard baud rate crystals (1.8432MHz, 2.4576MHz, or
3.072MHz). A programmable buffered clock output
(BAUDOUT) provides either a buffered oscillator or 16X (16
times the data rate) baud rate clock for general purpose
system use.
To meet the system requirements of a CPU interfacing to
an asynchronous channel, the modem control signals RTS,
CTS, DSR, DTR, RI, DCD are provided. Inputs and outputs
have been designed with full TTL/CMOS compatibility in
order to facilitate mixed TTL/NMOS/CMOS system design.