What is a 5250?

The 5250 is a type of green-screen terminal that was commonly used in the 1970s and 1980s as an interface to mainframe computers. The name "5250" comes from the IBM System 5250, which was a series of terminals developed by IBM for use with its midrange AS/400 and System/36 computers.

The 5250 terminal typically had a monochrome or color screen with a resolution of 24 lines by 80 characters. It featured a keyboard with function keys, a numeric keypad, and a variety of special keys for interacting with the mainframe computer. The terminals used a proprietary communication protocol known as the "5250 data stream" to communicate with the host computer.

One of the key features of the 5250 terminal was its "green screen" display, which used black text on a green background. This color scheme was chosen to reduce eye strain for users who spent long hours working at the terminal.

Despite being considered outdated by modern standards, the 5250 terminal is still used in some legacy systems that have not been updated to newer technology. The terminal is known for its reliability and robustness, making it a popular choice for businesses that rely on older mainframe systems.