CHAPTER 6: The Little Man Computer

1. CHAPTER 6:The Little Man Computer The Architecture of Computer Hardware and Systems Software: An Information Technology Approach 3rd Edition, Irv Englander John Wiley and Sons ?2003 Linda Senne, Bentley College Wilson Wong, Bentley College

2. Chapter 6 Little Man Computer 6-2 Introduction The power of the computer does not arise from complexity. Instead, the computer has the ability to perform simple operations at an extremely high rate of speed. These operations can be combined to provide the computer capabilities that you are familiar with.

3. Chapter 6 Little Man Computer 6-3 LMC – Little Man Computer Original was created by Dr. Stuart Madnick at MIT in 1965. He produced a newer version in 1979. The newer version has a slightly modified instruction set. We will use the modified version.

4. Chapter 6 Little Man Computer 6-4 The Little Man Computer

5. Chapter 6 Little Man Computer 6-5 Mailboxes: Address vs. Content Addresses are consecutive Content may be Data or Instructions

6. Chapter 6 Little Man Computer 6-6 Content: Instructions Op code Operation code Arbitrary mnemonic Operand Object to be manipulated Data or Address of data

7. Chapter 6 Little Man Computer 6-7 Magic! Load program into memory Put data into In Basket

8. Chapter 6 Little Man Computer 6-8 Assembly Language Specific to a CPU 1 to 1 correspondence between assembly language instruction and binary (machine) language instruction Mnemonics (short character sequence) represent instructions Used when programmer needs precise control over hardware, e.g., device drivers

9. Chapter 6 Little Man Computer 6-9 Instruction Set –Direct Addressing

10. Chapter 6 Little Man Computer 6-10 Instruction Set –LOAD (Direct)

11. Chapter 6 Little Man Computer 6-11 Instruction Set –STORE (Direct)

12. Chapter 6 Little Man Computer 6-12 Instruction Set –ADD (Direct)

13. Chapter 6 Little Man Computer 6-13 Instruction Set –SUB (Direct)

14. Chapter 6 Little Man Computer 6-14 Instruction Set –INPUT

15. Chapter 6 Little Man Computer 6-15 Instruction Set –OUTPUT

16. Chapter 6 Little Man Computer 6-16 Instruction Set –HALT

17. Chapter 6 Little Man Computer 6-17 Instruction Set –SKIP

18. Chapter 6 Little Man Computer 6-18 Instruction Set –JUMP (Direct)

19. Chapter 6 Little Man Computer 6-19 What does this program do? 00 IN; 01 STA 99; 02 IN; 03 ADD 99; 04 OUT; 05 HLT; Write the opcode.

20. Chapter 6 Little Man Computer 6-20 What does this program do? 00 IN; 01 STA 99; 02 IN; 03 STA 98; 04 ADD 99; 05 STA 97; 06 LDA 99; 07 OUT; 08 LDA 98; 09 OUT; 10 LDA 97; 11 OUT; 12 HLT;

21. Chapter 6 Little Man Computer 6-21 Write a program to… Enter two number. Find (and output) the sum of twice the first number plus the second number. Enter two number. Compute the sum of twice the first number and three times the second number. Output the first number, then the second number, then the result.

22. Chapter 6 Little Man Computer 6-22 INDIRECT ADDRESSING

23. Chapter 6 Little Man Computer 6-23 Instruction Set –LOAD (Indirect)

24. Chapter 6 Little Man Computer 6-24 Instruction Set –STORE (Indirect)

25. Chapter 6 Little Man Computer 6-25 Instruction Set –ADD (Indirect)

26. Chapter 6 Little Man Computer 6-26 Instruction Set –SUB (Indirect)

27. Chapter 6 Little Man Computer 6-27 Instruction Set –JUMP (Indirect)

28. Chapter 6 Little Man Computer 6-28 Immediate Addressing

29. Chapter 6 Little Man Computer 6-29 Instruction Set –LOAD (Immediate)

30. Chapter 6 Little Man Computer 6-30 Instruction Set –ADD (Immediate)

31. Chapter 6 Little Man Computer 6-31 Instruction Set –SUB (Immediate)

32. Chapter 6 Little Man Computer 6-32 Indirect, Immediate, Direct 00 IN; 01 STA 99; 02 ADD #05; 03 STA *99; 04 ADD *99; 05 OUT; 06 SUB *99; 07 OUT; 08 HLT;

33. Chapter 6 Little Man Computer 6-33 Indirect, Immediate, Direct 00 IN; Input a number > 10 to the calculator 01 STA 99; Direct Addressing--Store data in calc to mailbox 99 02 ADD #05; Add the number five to the calculator 03 STA *99; Indirect addressing- Store contents of calculator ; to the mailbox pointed to by the contents ; of mailbox 99 04 ADD *99; Indirect addressing; Add contents of mailbox pointed by 99 to contents of the calculator 05 OUT; 06 SUB *99; Indirect addressing-- Subtract contents of mailbox ;pointed to by the contents of mailbox 99 07 OUT; Print out result in calculator to output basket 08 HLT; End program

34. Chapter 6 Little Man Computer 6-34 Counting Forward INFINITE 00 LDA 90; 01 OUT; 02 ADD #01; 03 STA 90; 04 JMP 01; 05 HLT; 90 DAT 00;

35. Chapter 6 Little Man Computer 6-35 Counting up to an enter num 00 IN; 01 STA 99; 02 LDA 90; 03 OUT; 04 ADD #01; 05 STA 90; 06 LDA 99; 07 SUB #01; 08 SKN; 09 JMP 01; 10 HLT; 90 DAT 00;

36. Chapter 6 Little Man Computer 6-36 LMC Input/Output

37. Chapter 6 Little Man Computer 6-37 LMC Internal Data

38. Chapter 6 Little Man Computer 6-38 Data storage location Physically identical to instruction mailbox Not located in instruction sequence Identified by DAT mnemonic

39. Chapter 6 Little Man Computer 6-39 LMC Arithmetic Instructions

40. Chapter 6 Little Man Computer 6-40 Instruction Cycle Fetch: Little Man finds out what instruction he is to execute Execute: Little Man performs the work.

41. Chapter 6 Little Man Computer 6-41 Fetch Portion ofFetch and Execute Cycle

42. Chapter 6 Little Man Computer 6-42 Fetch, cont.

43. Chapter 6 Little Man Computer 6-43 Execute Portion

44. Chapter 6 Little Man Computer 6-44 Execute, cont.

45. Chapter 6 Little Man Computer 6-45 von Neumann Architecture (1945) Stored program concept Memory is addressed linearly Memory is addressed without regard to content