8) From Transistors To Computers

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Materials:
digital integrated circuits catalog, optional: digilab thingy.

To begin learning about building complex critters out of parts, lets explore the complex machines already around us.

how do computers work? how do they decode the keyboard and get letter shapes on the screen? how fast? go through the levels of complexity from the digital gates made out of transistors up to digital circuits made of 10s 100s thousands of gates

start with that old Signetics catalog I had when I was a kid. notice how a half a dozen transistors fit together to make a seamlessly working logic gate, already sophisticated behavior. then see how to fit some gates together to make a flip flop, a decoder, a multiplexer, a timer.

If possible use a digi-lab to build a few different simple digital circuits out of the same gates.

now watch how to fit those chips together to make arithmetic units, circuits to display numbers on displays.

now see how to fit 'em all together to make a microprocessor, the central processor unit, the ram, the keyboard decoder.




ALTERNATE IDEAS of how to do this at a science center or museum:


8) well you can certainly have a bare computer chip a basic one, like an 8080 or something, see how tiny, then another under microscope see a hint at the complexity, then a wall sized blow up, then..

9) diagram of the various circuits, flip flops, multiplexers... how they work

how does someone look and realize how they work? animations of how the signals go though them.. you can even have a table where you put in a grid of cubes... a giant sized digiboard! with signal inputs with LEDs. you put a logic gate on a signal input and see the output, then you look at the diagrams and put the blocks together. have blocks with those numeric displays.. how do you match up the leads? a numeric display will have 7 inputs per digit. what's the geometry here? make it big enough so that it has 8 block faces: 3 blocks long, then you have to snake the other block outputs to them, need a way to cross wires, that's a block! a wire cross block.

bar that's insane! do you know how big the damn thing will have to be? how much can you do with a grid on a wall panel? the blocks stick to it. make 'em.. i was thinking 2X2 inches to make it easy to handle. so a grid (it's gonna be little kids!) 6feet wide by 2feet tall is 36X12 blocks. is that enough to make ciruits? then chunk the circuits but then there is the problem of leads... nope! have blocks that represent various combinations of 4 wires at a time split 8 wires into different directions: 8 input on one face and it's 4 blocks long and the 8 other faces are one lead out each.

it would take much too long to make a circuit on this!!

need a better idea. but bar it would be cool! kids would love it!

well? at least display of how to combine transistors to make two different gates

next level how to combine bunch of gates to make circuits clock, counter...

next level how to combine these to make central processor

animations showing how the signals work... could be a short movie like they have at these places.

[hell bar, think the whole complexity lab thing out as a video series like nova or...oh. nah.. it's got to be interactive!]

you can make the circuits show the signals going though at each step if you have the kid be the clock, he clocks it at his own pace to follow through, if he gets lost he resets it. he has switches he can flick up or down to set up the inputs...