OO software systems are systems of interacting objects.

Transcription

1 OO software systems are systems of interacting objects. Objects have Objects properties: these are things that objects know e.g. what you had for breakfast behaviors: these are things objects do e.g. being able to reply to the question What did you have for breakfast?

2 CSE115 / CSE503 Introduction to Computer Science I Dr. Carl Alphonce 343 Davis Hall alphonce@buffalo.edu Office hours: Tuesday 10:00 AM 12:00 PM * Wednesday 4:00 PM 5:00 PM Friday 11:00 AM 12:00 PM OR request appointment via * Tuesday adjustments: 11:00 AM 1:00 PM on 10/11, 11/1 and 12/6

3 Dr. Carl Alphonce Sapphire project Dr. Bina Ramamurthy

4 ANNOUNCEMENTS Dr. Carl Alphonce

5 Robotics Club

6 Dr. Carl Alphonce Class today ROADMAP Announcements (Robotics BBQ, Sapphire project) Instruction decoding Fetch/Decode/Execute cycle Low-level and high-level languages Coming up Expressions and objects

7 Dr. Carl Alphonce Please turn off and put away electronics: PROFESSIONALISM cell phones pagers laptops tablets etc.

8 REVIEW Dr. Carl Alphonce

9 AND gate inputs are on left output is on right 0 or 1 For which input values is output 1? For which input values is output 0?

10 Truth table for AND Input 1 Input 2 Output

11 OR gate inputs are on left output is on right For which input values is output 1? For which input values is output 0?

12 Truth table for OR Input 1 Input 2 Output

13 NOT gate input is on left output is on right For which input value is output 1? For which input value is output 0?

14 Truth table for NOT Input Output

15 MEMORY Dr. Carl Alphonce

16 Flip-flop (a bit of memory!) R (reset) S (set) remembered value

17 Computer Organization Memory (RAM) Processor (CPU) R1 R2... R16 PC IR ALU

18 MOVING ON Dr. Carl Alphonce

19 Dr. Carl Alphonce INSTRUCTION DECODING

20 Example: Digital Equipment Corp PDP 11 Encoding instructions photo credit: by Dave Fischer

21 Encoding instructions (PDP 11)

22 Encoding instructions (PDP 11) a sequence of 0s and 1s bit groupings

23 Encoding instructions (PDP 11) a sequence of 0s and 1s bit groupings OpCode Arg1 Arg2 general pattern

24 Encoding instructions (PDP 11) a sequence of 0s and 1s bit groupings OpCode Arg1 Arg2 general pattern ADD Reg1 Reg2 specific instruction

25 ADD OP CODE R1 R2 Instruction decoding Circuitry to decode rest of instruction and carry it out ( execute the instruction) This wire will carry a 1 only if the op code of the instruction is 0110.

26 Instruction decoding OP CODE R1 R2 t t t t t t t t t t t t t t t t This wire will carry a 1 only if the op code of the instruction is This wire will carry a 1 only if the op code of the instruction is This wire will carry a 1 only if the op code of the instruction is 1110.

27 Controlling information flow Data from a register Data to ALU

28 Dr. Carl Alphonce FETCH DECODE EXECUTE cycle

29 Fetch-Decode-Execute cycle Fetch an instruction (& update PC) Decode instruction Execute instruction Execute Fetch (load instruction into IR from location in PC) Decode Update PC

30 Language levels 1940s HARDWARE

31 1940s Language levels MACHINE LANGUAGE ( ) HARDWARE

32 1940s Language levels ASSEMBLY LANGUAGE (ADD R1 R2) MACHINE LANGUAGE ( ) HARDWARE

33 1940s Language levels ASSEMBLY LANGUAGE (ADD R1 R2) MACHINE LANGUAGE ( ) ASSEMBLY HARDWARE

34 1950s Language levels HIGH LEVEL LANGUAGE (e.g. Java) x + y ASSEMBLY LANGUAGE (ADD R1 R2) MACHINE LANGUAGE ( ) ASSEMBLY HARDWARE

35 1950s Language levels HIGH LEVEL LANGUAGES x + y ASSEMBLY LANGUAGE (ADD R1 R2) MACHINE LANGUAGE ( ) COMPILATION ASSEMBLY HARDWARE

36 Language levels HIGH LEVEL LANGUAGES x + y ASSEMBLY LANGUAGE (ADD R1 R2) MACHINE LANGUAGE ( ) }LOW LEVEL LANGUAGES HARDWARE

37 High level languages Java We can write, z = x + y instead of something like this, MOV (R3) R1 MOV (R4) R2 ADD R1 R2 MOV R2 (R5) Others: C#, Erlang, Python, ML, Prolog, Lisp, etc.

38 Dr. Carl Alphonce NOTE Differences between book s & lecture s presentation of code

39 Dr. Carl Alphonce I pointed out that the text s early code examples are quite involved. We will discuss the details in lecture over the next several days. The following slides give a sense of the order in which we will have our discussion. DO NOT PANIC if you do not yet understand the book s code examples at this point we don t expect you to.

40 Dr. Carl Alphonce [zybook] Figure 2.1.1: Using objects public class AttendanceExample { } public static void main(string[] args) { } PeopleCounter attendeecounter = new PeopleCounter(); attendeecounter.incrementcount(); attendeecounter.incrementcount(); attendeecounter.incrementcount(); System.out.print("Attendee count: "); attendeecounter.printcount(); return; This is a code example from chapter 2 of the zybook.

41 Dr. Carl Alphonce public class AttendanceExample { public static void main(string[] args) { PeopleCounter attendeecounter = new PeopleCounter(); attendeecounter.incrementcount(); attendeecounter.incrementcount(); attendeecounter.incrementcount(); Expression } } System.out.print("Attendee count: "); attendeecounter.printcount(); return; We will start by discussing this bit of code: an expression.

42 Dr. Carl Alphonce public class AttendanceExample { public static void main(string[] args) { PeopleCounter attendeecounter = new PeopleCounter(); attendeecounter.incrementcount(); Variable declaration } } attendeecounter.incrementcount(); attendeecounter.incrementcount(); System.out.print("Attendee count: "); attendeecounter.printcount(); return; Next we will discuss variable declarations.

43 Dr. Carl Alphonce public class AttendanceExample { public static void main(string[] args) { PeopleCounter attendeecounter = new PeopleCounter(); Assignment statement } } attendeecounter.incrementcount(); attendeecounter.incrementcount(); attendeecounter.incrementcount(); System.out.print("Attendee count: "); attendeecounter.printcount(); return; And then assignment statements.

44 Dr. Carl Alphonce public class AttendanceExample { public static void main(string[] args) { PeopleCounter attendeecounter = new PeopleCounter(); attendeecounter.incrementcount(); attendeecounter.incrementcount(); attendeecounter.incrementcount(); Method call } } System.out.print("Attendee count: "); attendeecounter.printcount(); return; Method calls will also be discussed, in their various forms.

45 Dr. Carl Alphonce public class AttendanceExample { public static void main(string[] args) { PeopleCounter attendeecounter = new PeopleCounter(); attendeecounter.incrementcount(); attendeecounter.incrementcount(); Method definition } } attendeecounter.incrementcount(); System.out.print("Attendee count: "); attendeecounter.printcount(); return; As well as method definitions.

46 Dr. Carl Alphonce public class AttendanceExample { public static void main(string[] args) { PeopleCounter attendeecounter = new PeopleCounter(); attendeecounter.incrementcount(); attendeecounter.incrementcount(); Class definition } } attendeecounter.incrementcount(); System.out.print("Attendee count: "); attendeecounter.printcount(); return; And eventually class definitions.