5) Panel switch scanning
In similar fashion to keyboard scanning, 2-bit addresses in the range AO-Al are decoded by the address decoder LSI139 (IC18) and supplied to the switch matrix. The output goes to octal buffer HC240 (IC16) (the same as used by the keyboard) and is passed to the data bus.
6) LED Display
The LED display is software controlled. Latch HC374 (IC22, IC24) takes LCD display data from the DO-D7 8-bit data bus to operate LED drivers 54513 and 54562.
7) Digital delay
The K LM-775 board has its own dedicated delay gate array, pPD65010CW-113. The delay circuit comprises this gate array, 64KB dynamic RAM x 2, ADC, DAC, and analog compander. The delay time can be specified.