16550

(redirected from 16550 UART)
Also found in: Wikipedia.

16550

(hardware)
A version of the 16450 UART with a 16-byte FIFO. Superseded by the 16550A.

This chip might not operate correctly with all software.

The 16C550 is a CMOS version.

UART

(Universal Asynchronous Receiver Transmitter) The electronic circuit that makes up the serial port. Also known as "universal serial asynchronous receiver transmitter" (USART), it converts parallel bytes from the CPU into serial bits for transmission, and vice versa. It generates and strips the start and stop bits appended to each character. Note that in the following paragraphs, dashes have been added after the 16 for readability. Older 8250 and 16-450 UARTs are not fast enough for today's modems. A 16-550 is required for transmission up to 115,200 bps (115 Kbps).

ISDN users running both 64 Kbps channels are losing performance with a 16-550 UART, because the maximum 115 Kbps is reduced further to 92 Kbps when the start/stop bits are removed. Upgrading to a 16-650 or higher UART boosts real data speed from 92 to 128 Kbps. The 16-650 is the more sophisticated UART, providing hardware flow control that reduces the burden on the CPU. See UART overrun.

 Buffer    MaximumUART    Size      SpeedChip    (bytes)   Bits/sec
   8250     None        9,600
   16450       1        9,600
   16550      16      115,200
   16650      32      430,800
   16750      64      921,600
   16850     128          1.5 Mbps
References in periodicals archive ?
Required for Multiplayer: Type and frequency of processor: Pentium 200 MHz (or compatible); 1 CD Per PC for all multiplayer modes; 2 to 8 players: Via local network: IPX or TCP/IP (requires network card) or Via Internet: TCP/IP or IPX (requires at least a 28.8 kbps modem and Internet Service Provider); 2 players: Via direct modem connection (requires a 28.8 kbps connection) or Via serial cable link (requires null modem cable and 16550 UART high speed serial port)
If high-speed printing, file transfers and downloading are important chores for your computer, install high-speed ports--a 16550 UART chip and a EPP parallel port.
For example, most internal modems utilize the 16550 UART, whose 16-character buffer enhances high-speed and background performance.
The ProClass 288HC and PM288HC// are based on a 16550 UART, providing a 16-character buffer to enhance background and multi-tasking performance.
Both versions provide support for use of serial ports or non-intelligent multi-ports boards, data rates to 115200 bps, RTS/CTS and XON/XOFF flow control, inbound calling, use of the 16550 UART in FIFO mode, multiple communications program interfaces, collection of accounting records at the server, use of the client software on the server station, advanced port allocation features including concurrent usage, "camp-on," automatic line allocation retry and port grouping.
[NMP.sup.2] includes several new features: most importantly, users can now utilize high-speed modems (v.32, v.42, and v.42 bis) without fear of data loss because [NMP.sup.2] is specially designed to work with the new 16550 UART. Additionally, [NMP.sup.2] can be installed either as a dedicated server to maximize performance, or as a non-dedicated server to maximize cost effectiveness.
operation in high-speed serial applications, the board's high-performance 160950 UART includes 128-byte FIF0s, eight times larger than those found on standard 16550 UARTs. Additionally, the 160950 UART supports 9-bit framing and is fully software compatible with legacy UART applications.