Why did you implement the D16 control unit as microprogrammed, rather than with (faster) random logic?
In fact, the D16 began with a random-logic control unit. But after I had designed it to the last gate, I found that it would not fit on the Augat wire-wrap board I had on hand. I figured that I could reduce the chip-count considerably by going to a microprogrammed control unit, and so I re-designed the machine; as I worked, I decided that I preferred microprogramming anyway. The irony is that when I was done, the new design didn’t fit the board either! Some time later, I chanced upon a larger Augat board, and the new microprogrammed design fit it with room to spare.
