If you have ever looked at a microcontroller's datasheet, you have probably seen something about registers. Registers are little one or two byte memory storage units in microcontrollers. The register in this instructable can hold 3 bits of data (b/c I ran out of room on my breadboards) using transistors. I did this to prove that I can, however, its not practical as an 8 bit register requires 64 transistors, about 64 resistors and lots of space.
The register is a neat device. It can recieve data when the enable input is, in my circuit, low and it can then latch and save the data even it the data line is changing. My circuit is not the conventional D-type latch because it used more transistors than I had.
Step 1: Materials
The materials for this project are quite simple as it is a prototype kind of project.
8 NPN transistors for each bit - mine is 3 bits (do the math)
8 resistors for each bit - 1K for the supply connection and 1K or more for signal. get a few more (you will need some more)
A pushbutton switch - N.O.
A DIP switch - at least 4 switches
A solderless breadboard - if you dont have one then your missing out because these things are great
An LED for each register to display the stored bit
Pliers are a great help for placing wires in tight places