8080 Assembler-Text Editor (ATE)

These days you can do it with a small GAL (like a 16V8), but it's not quite as obvious as it sounds. There are only 8 product terms per output, and IIRC some segments are on for more than 8 of the input combinations. What you do is that if there are 8 or fewer input combinations that turn on a given segment, you program the product terms for those combinations, if there are 8 or more, you program the product terms for the input combinations where that segment is _off_, and then invert the signal in the output logic macrocell. Another trick was to use the 7447 for 0-7 (or 0-9, depending on how you felt), decode the other 8 or 6 inputs using a 1-of-n decoder (like a 7442), and re-encode those with a diode matrix, blank the outputs of the 7447 for those input combinations (either using the blanking input, or by forcing the data inptus to 1111) and finally logically OR the outputs of the diode matrix and the 7447 -tony