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Some subroutines are so useful that they are always loaded into the computer which is called the OS. The computer’s OS determines most of the look and feel of the interface to the user. It also governs the interface between the computer and whatever program is being run, since the OS’s subroutines provide the program with a set of operations that are richer and more complex than the machine-language instructions.

3 major steps: First, a FSM can be extended, by adding a storage device called a memory, which will allow the machine to store the definitions of what it’s asked to do; second, this extended machine can follow instructions written in machine language, a simple language that specifies the machine’s operations; third, machine language can instruct the machine to interpret the programming language—for instance, Logo.

Algorithm Analysis

A skilled programmer is like a poet who can put into words those ideas that others find inexpressible.

firing squad problem

An even simpler example of a finite-state machine is the retractable ballpoint pen. This finite state machine has two possible states—extended and retracted—and the pen remembers whether its button has been pressed an odd or an even number of times. All finite-state machines have a fixed set of possible states, a set of allowable inputs that change the state, and a set of possible outputs.

By clever design, you can implement a circuit using far fewer building blocks than the preceding strategy requires. Puzzles like this come
up in the course of designing a computer, which is part of what makes the process fun.

Any function that can be specified by an input/output table of 0’s and 1’s

This hierarchical structure of abstraction is our most powerful tool in understanding complex systems, because it lets us focus on a single aspect of a problem at a time. we can talk about Boolean functions like And and Or in the abstract, without worrying about the technology. It means that almost everything we say about computers will be true even when transistors and silicon chips become obsolete.

The implementation technology must produce perfect outputs from imperfect inputs, nipping small errors in the bud. This is the essence of digital technology, which restores signals to near perfection at every stage.

I am always fascinated by how a pattern can create reality.

The water pressure in the pipes is analogous to the voltage on the wires, and the hydraulic valve is analogous to the metal-oxide transistor.

...the game consequently loses its charm: once both players learn the patterns, each game invariably ends in a tie. Tic-tac-toe is a good example of a computation precisely because it wavers on this line between the complex and the simple. Crossing that line is
what computation is all about. Computation is about performing tasks that seem to be complex by breaking them
down into simple operations.

The computer is not just an advanced calculator or camera or
paintbrush; rather, it is a device that accelerates and extends our processes of thought. It is an imagination machine, which starts with the ideas we put into it and takes them farther than we ever could have taken them on our own.

I etch a pattern of geometric shapes onto a stone. To the uninitiated, the shapes look mysterious and complex, but I know that when arranged correctly they will give the stone a special power, enabling it to respond to incantations in a language no human being has ever spoken.

... College. Situations are softened, stripped of severity and any kind of seriousness, any real punishment. People read this story, heard frat, athlete, hookup, enjoy. That word bank was all they needed for the whole scene to come to life.

I put the memory of that morning inside a large jar. I took this jar and carried it down, down, down, flights and flights of stairs, placing it inside a cabinet, locking it away, and walking briskly back up the stairs to continue with the life I had built. Now jars filled every inch of my mind. I had nowhere to put them. They cluttered the stairwells, could not be contained in cabinets. I was full of these sealed.

"I put the memory of that morning inside a large jar. I took this jar and carried it down, down, down, flights and flights of stairs, placing it inside a cabinet, locking it away, and walking briskly back up the stairs to continue with the life I had built."