LLTP - Light Logic Transistorless Processor

December 11, 2022 - Yup, sounds like a weight reduction goal and this is the first phase. My wall sized panels were.......Well....... wall sized and taking up too much space. This first step is wiring the State Machine onto some perf board and once that is de-bugged I will do the same for the ALU. The following is the major parts layout for the SM.

June 18, 2022 - I have spent way too much time away from my Light Logic projects but recently had the idea to take the current LLTP build and re-think the logic gates I have been using and try to reduce the number of gates used. The Full Adder seems to be the first area to work on and I have started on testing a Adder on Logisim that instead of using only Nand gates I will make use of a pair of Xnor gates and a 2 X 1 Mux. This will reduce the Light Logic gate count from nine to six gates for a single bit Full Adder. Over the course of a four or eight bit adder this will save me quite a few gates. Each gate requires a single opto coupler/vactrol an a few support diodes.

Logisim likes the circuit so far, so next will be a actual build and test.

December 31, 2021

Not earth shattering but here are the final circuits for Light Logic. Happy New Year to everyone.

December 28, 2021 - After a bit of an absence I started improving on some of my Light Logic gate circuits. I was never satisfied with how my XNOR gate turned out so I ended up having a dream last night and when I woke up this morning I got to working on what I had dreamed about. The simple change is that I now feed 5 volts to the inputs continuously through a pair of 150R resistors. If there is no input at either A or B then the input is considered HIGH. If either A or B is grounded through a previous gate then the input is LOW. The Out of the LDR can be followed by a Light Logic Inverter gate to create a XOR gate or wired to any other gate as needed. I have this circuit on a bread board and it is working as it should. Remember, with Light Logic  the output MUST be through the LDR to ground to be a counted as a solid Zero / Low. Anything else is counted as a One / High

November 1, 2021 - Finally finished up the newest D-Latch with a added output buffer. This build works just as well as the wall mounted LLTP D-Latches and is about as small as I can make with my standard way of hand making my Vactrols. The solder side is not pretty but the same layout as if it were a PCB.

Just to recap, the added output buffer is needed as the Q output can be de-latched when fed directly to the next stage such as a adder or another part of the processor.

October 25, 2021 -  I have been idle on the LLTP for a little longer than I wanted but I have been doing a bit of mind games on where to go with the construction of this 4 bit no transistor processor. I am trying out my standard Light Logic Vactrol devices on a copper perf board and making the parts placement as tight as I can.  The follow images look promising and show the partial wiring of a one bit latching memory. So instead of a design that will take up the walls of my lab, the new reduced design will only take up a table or desk top or mounted on something like a motherboard.

April 6, 2021 - just for grins and future use. A Light Logic 4 input NAND gate where all the diodes are Leds and in free form without the paper and fasteners.

March 20, 2021 - I'm back and melting solder once again. I adapted the hex display used on the Cardboard Computer - IO project and replaced the transistors with Light Logic. The display is not perfect by a long shot but it does work.

January 20, 2021 -  Well now, where to begin. My last entry was on December 5th and the very next day I started feeling a bit odd. My sense of smell and taste vanished in a matter of days and just felt weak. By Dec 10th I had lost 10 pounds of fluids and I felt that I had to go to the ER. Many tests and scans done and YUP, Covid-19. I was put on IV and felt a little better after that but for the next 4 days I was running a fever that would not break. I was having a hard time breathing by this point so off to the ER again. CT scan did not show any lung issues to be worried about but was given another IV, That's now two liters plus a steroid of some sort. Given a script and went home. The fever broke about four days later and I have been making slow progress. Now by Jan 20 I have my energy back in full though still have a bad cough from time to time. This has been a roller coaster ride that I would not wish on anyone. My appetite has also changed as I feel hungry but can only manage about half of what I used to eat. After my fluids were back to normal and my weight briefly returned to 254 pounds. My reduction in eating has me down to 239 as of this morning. I look forward to losing some weight but by way of the CV is not advised.

I will get back to this project as I have sat on my arse for too long :-)