keyboard encoder

C. Voss digital keyboard At first sight, this circuit looks rather complicated. It is a keyboard encoder, and it performs the following function: Each of the keys, up to a maximum of 64, are allocated a binary number. This binary number is available in the form of 6 bit 0 utputs of IC1 and IC2. The parallel data at the logic level at the 08 output indicates whether or no one of the keys has been depressed. The outputs 01 ... 06 and Q8 can be connected to a micro- processor system, or alternatively, they can be connected to a digital-to-analogue converter and used to control a music synthesiser. Since the outputs 01 . . . Q6 remain in the same state after the key is released, there is no need for a sample the correct polarity. The keyboard driver, IC3, has open collector outputs so that when a number of keys are de pressed at the same time, no outputs are shorted together. Depending on the particular application of the circuit, complementary outputs are available and-hold circuit a...