I was made aware of Erics earlier work on NE555 based logic. He actually came up with a pretty neat trick to turn the NE555 into more than just a boring inverter by also using the reset input of the NE555. This results in a logic function based on an AND-gate with one inverted input:
The naming of this type of gate is debatable, but I call it "ANDN2" in my library. It is actually fairly easy to implement this gate in PCBflow as well. I made a version of the dice where I enforced the AND2 and NOT gate to be the only type of logic gate being used:
Number of cells: 19 ne_ANDN2 10 ne_DFF 3 ne_NOT 6 Chip area for module '\main': 31.000000
Turns out the area is even smaller than withe the Diode/NE555 gates I used before. The reason for that is that no additional space is needed for diodes.
Unfortunately I had a lot of trouble simulating this logic style with spice. So instead of debugging issues with operating point I decided to take the pragmatic way and turn this into a board to test it rather in hardware. A rendering of the board is shown below. (I miss-spellt the gate type on the silk screen).
=== Component usage === Component Count pin 8 NE555 22 cap 22 npn transistor 6 resistor 18 ------------------ ----- Total: 76
This logic style requires a slightly higher count of NE555, 22 instead of 21. Not a bad trade-off, because many diodes are saved.
I should be able to test both versions in about two weeks.