Asynchronous communications

Synchronous and asynchronous

Asynchronous communications
This is the method most widely used for PC or simple terminal serial communications.In asynch. serial communication, the electrical interface is held in the mark position between characters.
Synchronous communications
In synchronous communications, data is not sent in individual bytes, but as frames of large data blocks. Frame sizes vary from a few bytes through 1500 bytes for Ethernet or 4096 bytes for most Frame Relay systems.

Analog and digital
In analog technology, a wave is recorded or used in its original form.
In digital technology, the analog wave is sampled at some interval, and then turned into numbers that are stored in the digital device.

XON and XOFF

Command: xon
(C-a q, C-a C-q)
Send a ^Q (ASCII XON) to the program in the curr...