A Clever Cardboard Computer

CARDIAC Cardboard Computer

Back in the 70’s when computers were fairly expensive and out of reach for most people, [David Hagelbarger] of Bell Laboratories designed CARDIAC: CARDboard Illustrative Aid to Computation. CARDIAC was designed as an educational tool to give people without access to computers the ability to learn how computers work.

The CARDIAC computer is a single-accumulator single-address machine, which means that instructions operate on the accumulator alone, or on the accumulator and a memory location. The machine implements 10 instructions, each of which is assigned a 3-digit decimal opcode. The instruction set architecture includes instructions common to simple Von Neumann processors, such as load, store, add/subtract, and conditional branch.

Operating the computer is fairly simple–the cardboard slides guide you through the operation of the ALU and instruction decoder, and the flow chart shows you which stage to go to next. The program counter is represented by a cardboard ladybug which is manually moved through the program memory after each instruction completes.

Even though the CARDIAC is dated and very simplistic, it is still a useful tool to teach how microprocessors work. Although modern processors include multi-stage pipelines, finely-tuned branch predictors, and numerous other improvements, the basic principles of operation remain the same.

Feeling adventurous? Print out your own CARDIAC clone and try writing your first cardboard computer program.

[via Reddit]

From 0 to C: teaching programming without a computer

It’s no secret that learning how to program is very hard, and teaching it doubly so, requiring the student to wrap their head around very unorthodox concepts. [Ubi de Feo] over at the Amsterdam tech collective Hello, Savants! has a unique solution for taking someone who knows nothing of programming and turning them into a computer aficionado capable of deftly wielding semicolons and parens. It’s called From 0 to C, and aims to teach students programming in an environment without computers.

For his class, [Ubi] made up a lot of wooden boxes with eight subdivisions representing the bits in a byte. By putting ping-pong balls in each slot, [Ubi]‘s students can grasp the concept of counting by powers of two and quickly move on to hexidecimal and more advanced concepts like bit shifting.

After learning the ins and outs of how stupid computers actually are, [Ubi]‘s students then learn the syntax of a language of their choice (C, JavaScript, or Python, for example), and write a few programs.

Although we’re sure most of our readers are far past the ‘learning programming from a blank slate’ portion of their hacker and maker career, anything that gets more people solving their own problems is okay in our book. [Ubi] has a pretty neat take on the pedagogy of teaching programming, and we’d really like to see his work expand outside his Amsterdam collective.


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