# Logic

Digital logic uses the boolean logic represented with high and low voltage values:
depending on what voltage represents the /true/ value the logic is **active high** or **active low**.

With technology improvement the voltage ranges used to represent logic level has changed

| Technology | L Voltage | H Voltage |Notes |
|------------|-----------|-----------|------|
|CMOS        |0V to 1/3VDD|2/3 Vdd to Vdd|Vdd = supply voltage |
|TTL |0V to 0.8V | 2V to Vcc | Vcc = 5 +/- 10% |

## Combinatorial logic

 - [CMOS Gate Circuitry](http://www.allaboutcircuits.com/textbook/digital/chpt-3/cmos-gate-circuitry/)

## Sequential logic

 - [Sequential Logic Circuits](http://www.electronics-tutorials.ws/sequential/seq_1.html)

## TTL

 - [1988 TTL Logic Standard Data Book](https://ia801901.us.archive.org/4/items/bitsavers_tidataBookrdTTLSLSDataBook_39061488/1988_TTL_Logic_Standard_TTL_S_LS_Data_Book.pdf)

## Tri-state logic

 - Tri-state logic: Connecting multiple outputs together - 8 bit register - Part 2 [video](https://youtu.be/faAjse109Q8)

## Links

 - Making logic gates from transistors [video](https://www.youtube.com/watch?v=sTu3LwpF6XI)