When was serial port invented

Voltage sent over the pins can be in one of two states, On or Off. An important aspect of serial communications is the concept of flow control. This is the ability of one device to tell another device to stop sending data for a while. Let's look at an example of how flow control works: You have a modem that communicates at 56 Kbps. The serial connection between your computer and your modem transmits at Kbps, which is over twice as fast.

This means that the modem is getting more data coming from the computer than it can transmit over the phone line. Even if the modem has a K buffer to store data in, it will still quickly run out of buffer space and be unable to function properly with all that data streaming in.

With flow control, the modem can stop the flow of data from the computer before it overruns the modem's buffer. The computer is constantly sending a signal on the Request to Send pin, and checking for a signal on the Clear to Send pin.

If there is no Clear to Send response, the computer stops sending data, waiting for the Clear to Send before it resumes. This allows the modem to keep the flow of data running smoothly. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots.

Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Computer Hardware. How Serial Ports Work. By: Jeff Tyson. UART Needed " ". Most of today's computers are eliminating the serial port in favor of USB ports. Home Dictionary S - Definitions. Where is the serial port on a computer?

Identifying a serial port What is the serial port used for? Serial port pin information Related pages. Note With the introduction of USB , FireWire , and other faster solutions serial ports are rarely used compared to how often they've been used in the past. Note With many computers, the serial port is labeled as " " which are ones and zeros to represent binary.

Note Most of today's computers are eliminating the serial port in favor of USB ports. Related pages How to troubleshoot a new serial device. How to set up a direct cable connection in Windows 95 and It is true that it have been eliminated by the modern technology but still there are many devices which are only connected through serial port.

Sign in. Log into your account. Password recovery. Recover your password. Friday, November 12, Advertise Contact Us Login Sitemap. Forgot your password? Get help. Engineers Gallery. Share on Facebook. Pin Configuration of Serial Port: Serial port have total 9 pins. The purpose of pin 1 is Data Carrier Detect. It is used to detect the data stream which is being carried bu the buses for sending to other devices or for receiving.

The purpose of this pin is to monitor the data which is received by serial port from some external means. The purpose of this pin is to transmit data from serial port to the external module, where we wish to send data. Remember that serial port only transmit data at the rate of one bit per second. The purpose of this pin is to see the data which is to transmit but it has not been sent yet. The data is available at the sending port of serial port and it needs the go signal from micro processor.

This pin is used to determine the data transmission rate. Data is available at the port but it has not been sent yet.

This pin is the signal for sending the data to external means. When data is available at pin 3 of the serial port and to send this data you have to get permission from control circuit and pin 7 which is in fact RTS pin does this job.