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B ilgisayarlar kodu nasıl işler?

Learn about top-down and modular approaches in coding, advantages of breaking up code, storing code, different number systems, and representing alphanumeric information in computers.

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B ilgisayarlar kodu nasıl işler?

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  1. Bilgisayarlar kodu nasıl işler? • Top-down yaklaşım • Modüler yaklaşım

  2. Top down yaklaşım • In this scenario, when the code is run the computer starts reading at the top and continues down, going through each line of code until it reaches the end. • Old method • Fast and easy when code was small and not very complex • As the code is processed, it is all loaded into memory

  3. Top down yaklaşım • So, the more programs you run, the greater the demands on the system in terms of memory and processor

  4. Top down yaklaşım • Also, the bigger the program you are loading, the longer and longer it will take to load up

  5. Top down yaklaşım • One is that you have to write code in such a way that it is hard to properlytest it until you have finished it. • Testing individual parts becomes a nightmare.

  6. Breaking up Code • There are huge advantages to coding in this way. • The code is broken up into smaller components, so it is easier to write and you can test it earlierand more often. • Debugging any code errors is a lot easier because you know what part of the code handles whataspect of the program. • You are in a position to reuse certain parts of your code in other projects more easily becausethey will be self-contained. • Building up a big project from smaller, interconnected chunks enables you to build up a projectover time and add more features as your skills improve!

  7. Re-usability

  8. Kodun Saklanması (Depolanması) • To really make applications usable, you need a way to store the code • Storage means that you only have to type or ( more accurately) create the code once, storing it for future access • Paper punch cards • Magnetic tape reels • Magnetic cassettes • Floppy disks (51/ 4 inch) • Floppy disks (31/ 2 inch) • Hard drives • Networked systems • CDs • DVD • Flash drives • Internet distribution

  9. Data • Data stored as binary

  10. Plain text vs. Compiled • The code can be in one of two forms • Plain text (Sade metin): Some code that you will come across will be stored and run in the plain text form — JavaScript and VBScript are good examples of this • Compiled (Derlenmiş): This is code that has been run through a program called a compiler. The compiler processes the plain-text code and changes it into something called “object code.”

  11. Plain text vs. Compiled • Plain text • The main advantage to code stored in plain text is that it is easily read, changes can be made to it easilyand quickly, and no special tools are required. • No protection! • Compiled • You can’t look at the compiled code and get back to the source code that way. Therefore protected. • You need to keep a copy of the source code in case you need to make any subsequentchanges to the code.

  12. Sayı Sistemleri • Decimal (Onluk sayı sistemi, On tabanlı) • 0 1 2 3 4 5 6 7 8 9 • Örnek: 1984 • Binary (İkilik sayı sistemi, iki tabanlı) • 0 1 • Örnek: 10011 • Hexadecimal (Onaltılık sayı sistemi) • 0 1 2 3 4 5 6 7 8 9 A B C D E F • Örnek: 1A2

  13. Onluk Sisteme Dönüşümler • Sağdan sola doğru taban değerini hesapla • ..., Taban3, Taban2, Taban1, Taban0 • Basamak değeri ile taban değerini çarp • Çarpımları topla • Örnekler: • (1984)10= (?)10 • (10011)2= (?)10 • (1A2)16= (?)10

  14. Onluk Sistemden Dönüşümler • Dönüştürülecek tabana bölüm • Örnekler: • (1984)10= (?)10 • (19)10= (?)2 • (418)10= (?)16

  15. İkilik sayı sisteminde terimler • Bit - 0,1 • Nybble – 4 bit • Örnek: 1010 • Byte – 8 bit • Örnek: 10101010 • Halfword – 16 bit • Örnek: 1010101010101010 • Word – 32 bit • Örnek: 10101010101010101010101010101010 • Doubleword – 64 bit • Örnek: 1010101010101010101010101010101010101010101010101010101010101010

  16. Binary ve Hexadecimal arasında dönüşümler • 0x3F7D (3F7D)16=(?)2 3 F 7 D 0010 1111 0111 1101 10111101111101 (101111)2=(?)16 0010 1111 2 F 2F

  17. Binary ve Hexadecimal arasında dönüşümler

  18. Sayı sistemlerinde matematik işlemleri • Başlat – Programlar – Donatılar – Hesap Makinesi

  19. Bu sinyal ne anlama geliyor? • ...---…

  20. Bilgisayarda Alfasayısal Bilginin Temsil Edilmesi • ASCII (American Standard Code for Information Interchange) • Bilgi Değişimi için Amerikan Standart Kodu

  21. Programming is great! • 010100000111001001101111011001110111001001100001011011010110110101101001011011100110011100100000011010010111001100100000011001110111001001100101011000010111010000100001

  22. Why Binary? • Tartışma Sorusu: Bilgi işleme sistemlerinde neden ikilik sistemi kullanıyoruz? Neden Onluk sistemi ya da diğer bir sayı sistemini kullanmıyoruz? • İki kişilik gruplar halinde tartışınız.

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