Pin Serial

What is the data transfer rate of a 9 pin serial port? Best answer for 1st correct reply.?

Serial port transfers 1 bit at a time. USB does 480 megabits. What about PS/2?

THe standard 9-pin serial port can use many different transfer rates. It depends mainly on the hardware, usually a chip called a Uart (universal asynchronous receiver/transmitter.) The speeds start usually at 60 bps and can go to a maximum of 768000 bps. On older PCs the max was 9600 bps, and newer ones average 230,400 bps.
The standard protocol called RS232C defines the voltage levels, the connector and rates. The signal protocol is very simple, and each byte requires 3 additional bits for time purposes. RS232C allows for long cable lengths, officially up to 75 feet, but I know of at least one installation that used Serial cables of over 400 feet in length. There is a variation of the basic serial cabling, RS423, the uses a balanced transmission line (plain old telephone wire) for bit rates of up to 768k bps and distances of up to a mile.
By contrast the Universal Serial Bus (USB) specification is very limited in distance, and topheavy with protocol. RS232C has a 35% protocol overhead, USB varies from 3% for bulk transfers to as much as 640% overhead for short messages. In addition, RS232C error detection occurs on a byte by byte level, wiht the receiving device requesting single byte retransfers, and the USB protocol works at the packet level and requests packet retransfers., Once, while debugging a usb wireless device, the usb sniffer logged 8 retransmits on a series of 2k bulk data packets, apparently due to a bit of tarnish on a usb connector.

7 + 6 Pin to IDE Power Serial ATA SATA Data Cable Red