Keyboard terminal type identification.

A CRT terminal comprises a CPU and a keyboard having a key matrix, a microprocessor, and a set of switches. The microprocessor responds to a query (data set ready) signal from the CPU to read the states of the switches, and generate a sequence of characters indicating the particular characteristics of the keyboard. The first character indicates that the characteristics set by the switches are compatible with the microprocessor firmware, and whether the keyboard is hard or soft. The following characters indicate the states of the function keys - auto line feed, local or remote for <<hard>> (which produces characters in ASCII), plus control, capitals lock, and left and right shift for <<soft>> (which produces straight binary coded characters).