If you have seen my other instructable on ram memory, you probably know that I used transistors to make a register. In this instructable I will show you how to make a register using CMOS gates.
If you haven't seen my other instructable, check it out http://www.instructables.com/id/DIY-RAM-Memory-Register-Style/
Step 1: What is CMOS?
Step 2: Why use CMOS?
Step 3: What You Will Need
***These are per-bit numbers***
8 2N7000 Small signal n-channel mosfet
8 BS250 Small signal p-channel mosfet
2 Pushbutton switches
2 10K ohm resistors
1 1K ohm resistor (or whatever value is needed for your LED)
***These are necessary no matter how many bits you make***
pliers (not necessary, but very very close)
Step 4: How It Works
Step 5: The NAND Gate
A B Y
0 0 1
0 1 1
1 0 1
1 1 0
It requires 4 MOSFET to operate, 2 P-channels and 2 N-channels in the configuration below. The P-channel FETs are in parallel, but the N-channel FETs are stacked up, in a "Totem Pole" configuration. If either A or B is low, then current can flow through one of the the P-channel FETs, making Y logic 1. This is true to the truth table. If both A and B are high, then the P-channel FETs turn off and both N-channel FETs turn on, making Y logic 0. As true to the table.