# Beginner Concepts: Binary-coded decimal

A rudimentary understanding of digital logic and simple integrated circuits is critical if you’re ever going to pull off some really gnarly hacks. [Daniel] put together an explanation about the use of 4511 BCD 7-segment drivers. These chips take binary data in and output decimal data to a 7-segment LED display. In short, they can read 0b1001 from input pins and light the numeral ‘9’ on the display. The best part is that you can build this example circuit in the Atanua logic simulator without ordering parts. We love zero-cost learning!

## 13 thoughts on “Beginner Concepts: Binary-coded decimal”

1. I was so proud when I wired up my first BCD chip last month, I even made a video of it: http://bit.ly/8DjNaL

Mine was a MC14543B and I had all sorts of weird problems where lights would turn on / off depending on how close my hand was to the wires until I added pull-down resistors.

2. David says:

> In short, they can read 0×1001 from input pins and light the numeral ‘9′ on the display.

That’s a neat trick, since 0x1001 = 4097 in decimal.

3. TRB says:

think binary david :p

4. This was what got me into digital electronics and then computers more than 30 years ago. I built a 3-digit counter, and was completely shocked when it worked. My experiences with analog (ham radio) circuits had not been good, partly because my parents had little spare money so I made many poor parts substitutions from things like discarded TV sets. But the digital circuit was cheap, worked, and performed a surprisingly (back then) complex function.

1×1 plus 0x2 plus 0x4 plus 1×8 equals 9!

Rember there are 10 types of people in this world those who understand binary and those that don’t !

Sorry couldn’t resist ! Lol !

6. sol says:

These basic tutorials are great. Keep ’em coming and don’t let the assorted elitists on the comment threads convince you otherwise.

7. Hitek146 says:

7447 or 7448, anyone? :)

8. jme says:

0x1001 does equal 4097 decimal
it should read 0b1001 equals 9 decimal

Ahh yes! I guess I was fairly sleepy when I posted ! Of course 0x means that a hex number string follows so the correct way to describe 9 is 0b1001 ! Blame it on C ! I think a correction is due soon :-p

10. j s says:

Avago’s smart displays do the same thing using internal logic. They can be set to latch the output so when you remove the input the output remains.

11. keso says:

hey. can you send me the whole tutorial about constructing these? tnx.

12. sahabu says:

BCD of 43