Charles Petzold > Quotes

“Code is not like other how-computers-work books. It doesn't have big color illustrations of disk drives with arrows showing how the data sweeps into the computer. Code has no drawings of trains carrying a cargo of zeros and ones. Metaphors and similes are wonderful literary devices but they do nothing but obscure the beauty of technology.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Programming in machine code is like eating with a toothpick.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“In 1948, while working for Bell Telephone Laboratories, he published a paper in the Bell System Technical Journal entitled "A Mathematical Theory of Communication" that not only introduced the word bit in print but established a field of study today known as information theory. Information theory is concerned with transmitting digital information in the presence of noise (which usually prevents all the information from getting through) and how to compensate for that. In 1949, he wrote the first article about programming a computer to play chess, and in 1952 he designed a mechanical mouse controlled by relays that could learn its way around a maze. Shannon was also well known at Bell Labs for riding a unicycle and juggling simultaneously.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“We could just as reasonably base our number system on eight (if we were cartoon characters) or four (if we were lobsters) or even two (if we were dolphins).”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“To a programmer, an operating system is defined by its API.”
― Charles Petzold, Programming Windows

“The flip side of this is that any information that can be reduced to a choice among two or more possibilities can be expressed using bits. Needless”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Some people believe that Moore’s Law will continue to be accurate until about 2015.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“We don’t carry in subtraction, however; we borrow, and that involves an intrinsically different mechanism—a messy back-and-forth kind of thing.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Thus, 1 is actually a function with the two bound variables f and x. Just offhand, those two variables seem like two more variables than are needed to define a simple number.”
― Charles Petzold, The Annotated Turing: A Guided Tour Through Alan Turing's Historic Paper on Computability and the Turing Machine

“The method you use is something called the base two logarithm. The logarithm is the opposite of the power. We know that 2 to the 7th power equals 128. The base two logarithm of 128 equals 7.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“You’re twelve years old. One horrible day your best friend’s family moves to another town. You speak to your friend on the telephone now and then, but telephone conversations just aren’t the same as those late-night sessions with the flashlights blinking out Morse code. Your second-best friend, who lives in the house next door to yours, eventually becomes your new best friend. It’s time to teach your new best friend some Morse code and get the late-night flashlights blinking again.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Of particular interest is the number indicator and the letter indicator that undoes the number indicator. These codes alter the meaning of the codes that follow them—from letters to numbers and from numbers back to letters. Codes such as these are often called precedence, or shift, codes. They alter the meaning of all subsequent codes until the shift is undone. The capital indicator means that the following letter (and only the following letter) should be uppercase rather than lowercase. A code such as this is known as an escape code.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“In the same way that Morse code reduces written language to dots and dashes, the spoken version of the code reduces speech to just two vowel sounds. The key word here is two. Two types of blinks, two vowel sounds, two different anything, really, can with suitable combinations convey all types of information.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“That rare person who has 1,073,741,824 bytes of memory will say, “I’ve got a gig (and I’m not talking music).”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“This equivalence wasn’t discovered until the 1930s, most notably by Claude Elwood Shannon (born 1916), whose famous 1938 M.I.T. master’s thesis was entitled “A Symbolic Analysis of Relay and Switching Circuits.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Bits also play a part in logic, that strange blend of philosophy and mathematics for which a primary goal is to determine whether certain statements are true or false. True”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Замысел «Кода» я вынашивал лет десять. И тогда, и во время работы над рукописью, и даже когда книга вышла из типографии многие спрашивали: «О чем она?»”
― Charles Petzold, Код: тайный язык информатики

“I said early on in this chapter that we would need 144 relays for our adding machine. Here’s how I figured that out: Each”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Xamarin.Forms allows you to be as platform-independent or as platform-specific as you need to be. Xamarin.Forms doesn’t replace Xamarin.iOS and Xamarin.Android; rather it integrates with them.”
― Charles Petzold, Creating Mobile Apps with Xamarin.Forms, Preview Edition

“When the iPhone app is built, the Xamarin C# compiler generates C# Intermediate Language (IL) as usual, but it then makes use of the Apple compiler on the Mac to generate native iPhone machine code just like the Objective-C compiler. The calls from the app to the iPhone APIs are the same as though the application were written in Objective-C. For the Android app, the Xamarin C# compiler generates IL, which runs on a version of Mono on the device alongside the Java engine, but the API calls from the app are pretty”
― Charles Petzold, Creating Mobile Apps with Xamarin.Forms: Cross-Platform C# Programming for iOS, Android, and Windows Phone

“In 1914 the German government
asked prominent scientists and artists to sign a declaration refuting the "lies and
slanders of the enemy". Hilbert could not determine whether these statements
made about Germany were true (a rather political Entscheidung problem), so he
refused to sign.”
― Charles Petzold, The Annotated Turing: A Guided Tour Through Alan Turing's Historic Paper on Computability and the Turing Machine

“a digital design engineer, you would spend long hours going through the TTL Data Book familiarizing yourself with the types of TTL chips that were available. Once you knew all your tools, you could actually build the computer I showed in Chapter 17 out of TTL chips. Wiring the chips together is a lot easier than wiring individual transistors”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“If you want your appliance to work right, it’s a good idea to install the batteries correctly with the plus signs facing the right way.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Few fantasies tickle the human pleasure center more than a vision of relaxing in a hammock watching some newfangled contraption we just built mow the lawn.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Just as Morse code provides a good introduction to the nature of codes, the telegraph provides a good introduction to the hardware of the computer.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“communication simply requires”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Escape codes let you “escape” from the humdrum, routine interpretation of a sequence of codes and move to a new interpretation. As we’ll see in later chapters, shift codes and escape codes are common when written languages are represented by binary codes.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Today’s computers use transistors. When used in computers, transistors basically function the same way relays do, but (as we’ll see) they’re much faster and much smaller and much quieter and use much less power and are much cheaper. Building an 8-Bit Adder still requires 144 transistors (more if you replace the ripple carry with a look-ahead carry), but the circuit is microscopic.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Today’s computers use transistors. When used in computers, transistors basically function the same way relays do, but (as we’ll see) they’re much faster and much smaller and much quieter and use much less power and are much cheaper. Building an 8-Bit Adder still requires 144 transistors (more if you replace the ripple carry with a look-ahead carry), but the circuit is microscopic. Chapter 13. But What About Subtraction? After you’ve convinced yourself that relays can indeed be wired together to add binary numbers, you might ask, “But what about subtraction?” Rest assured that you’re not making a nuisance of yourself by asking questions like this; you’re actually being quite perceptive. Addition and subtraction complement each other in some ways, but the mechanics of the two operations are different. An addition marches consistently from the rightmost column of digits to the leftmost column. Each carry from one column is added to the next column. We don’t carry in subtraction, however; we borrow, and that involves an intrinsically different mechanism—a messy back-and-forth kind of thing. For example, let’s look at a typical borrow-laden subtraction”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software

“Yes, the earth is a massive conductor of electricity, but it can also be viewed as both a source of electrons and a repository for electrons. The earth is to electrons as an ocean is to drops of water. The earth is a virtually limitless source of electrons and also a giant sea of electrons.”
― Charles Petzold, Code: The Hidden Language of Computer Hardware and Software