Greetings Gents…
Posted by floatingman on October 7, 2008
I know all of you have been updating your feedreader constantly to see if I had posted anything. Well to tell you the truth I forgot which button to press on my control board to update my lifestream on the intertubes. Today I was inspecting my control board and saw this dusty button and wondered what is that for, so like a good scientest I closed my eyes and pressed it and here we are.
I thought I’d share some of the things I’ve been working on. I’m taking a system archetecture class which is really neat. It’s interesting learning all of the things you can do with 1s and 0s. The premise of the class is we are going to learn how to design these circuits and eventually put them all together to make a programmable computer. We use a program called Logisim to design the circuits.
Here are some of the circuits I’ve designed.
Full adder
This one will take a two 1-bit numbers and add them together and if both numbers are 1 it will have a carry out, which is helpful when adding multi-bit numbers. With Logisim once you design a circuit, you can use it in another circuit. That helps when designing complex circuits. By using divide and conquer, if you break a complex problem into simple steps it makes problem solving a whole lot easier. With the adders, I had to eventually design a 16-bit adder, which was easy by first designing a 1-bit adder and then incorporating that chip into a 4-bit adder and then incorporating that chip into a 16-bit adder.
4-bit adder
16-bit adder
I then used the 16-bit adder chip in the design of an Arithmetic Unit, or AU, which is one part of the Arithmetic Logic Unit, or ALU for short, a very important part of a computer.
Arithmetic Unit
This unit can do more than add. It can subtract, increment and transfer. I won’t go into the complexities of those operations, but if you are interested here’s a tutorial on doing 1s and 2s compliement arithmetic.
I bet you can’t guess what is the other part of the ALU? That’s right it’s the Logic Unit, or LU.
Logic Unit
It was a whole lot easier to design than the AU.
We put these all together and what do we get?
Arithmetic Logic Unit
So that’s what I’ve been working on for the past few weeks and I see that this post has grown rather tall so I’ll end it here.
Until next time, stay frosty.
