Hexadecimal display decoder

The byte to hex display decoder was designed because nibble to hex decoders are no longer produced commercially In Principle, it is, of course, not difficult to decode a nibble, but from byte to hex is generally more practical and requires fewer ICs. The decoder uses a GAL Type 22V10. This type has an adequate number of inputs and outputs for the present application and may be programmed with the GAL Programmer (incl. the extension) published in Ref. 1. The listing and programming data shown are written in the format that is accepted by the National Semiconductor software and may be converted by a JESSICA file with the EQN2JED option. Note that although a warning is generated that in the define statements an OR term is used, this is a false alarm, since in the present circuit no fewer than eight OR terms are produced. The circuit has a drawback in that it requires an external clock. Fortunately.

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