History of Computer Software

1
History of Computer Software

• Programming Languages
• Program Translation (Assemblers/Compilers)
• Interpreters

2
History of Programming Languages

• Machine Language
• Instructions use binary digits (ones and zeros)
• Used for the Jacquard Loom and Analytical Engine
• Need intimate knowledge of hardware design
• Difficult to write program / Worse to debug/fix
  program
• Example (Add 1 to memory at address 1000)
• 1000 1010 1001 1110 gt 8A9E (Load Register
  A from)
• 0001 0000 0000 0000 gt 1000 (Memory
  Location 1000)
• 1101 0101 0000 0001 gt B501 (Add 1 to
  Register A)
• 0000 1010 1001 1110 gt 0A9E (Store Register
  A in)
• 0001 0000 0000 0000 gt 1000 (Memory
  Location 1000)

3
History of Programming Languages

• Assembly Language
• Symbolic representation of binary instructions
• Need intimate knowledge of hardware design
• Easier to program than machine language
• Easier to debug/fix than machine language
• Still used today when high efficiency/speed are
  needed
• Example (Add 1 to memory at address 1000)
• START LDA 1000
• ADD 1
• STA 1000

4
History of Programming Languages

• High Level Languages
• Formula Translation (FORTRAN)
• Beginners All-purpose Symbolic Instruction Code
  (BASIC)
• Common Business-oriented Language (COBOL)
• Example (BASIC)
• 100 IF (ANGLE ! 90) GO TO 300
• 200 LET C SQRT(A2 B2)
• 300 CONTINUE

5
History of Programming Languages

• Block Structured Languages
• PASCAL
• C
• Ada
• Example (C)
• if (angle 90)
• c sqrt(aa bb)

6
History of Programming Languages

• Object-Oriented Languages
• C
• Java
• An Extension to Block Structured Languages
• Example of Object-Oriented Operation (Java)
• Dog rover new Dog(Rover, Poodle)
• String yip rover.speak()

7
Program Translation

• Conversion of Source to Machine Language
• The Rosetta Stone
• Human readable Source
• Intermediate Files
• Object File(s)
• Java Bytecode File(s)
• Machine Readable Binary

8
Bits and Bytes

• One binary digit a 1 or a 0 (e.g. on or off)
• A binary digit is called a bit
• One hexadecimal digit 4 bits
• One byte 8 bits
• A single character, e.g. A may 1 byte
• An integer may 4 bytes
• A floating point value, e.g. 4.1x104 8 bytes

9
Binary and Hexadecimal Bytes

• Counting in binary Counting in Hex
• 0000 0000 0x00
• 0000 0001 0x01
• 0000 0010 0x02
• 0000 1001 0x09
• 0000 1010 0x0a
• 0000 1111 0x0f
• 0001 0000 0x10

10
ASCII Codes for Characters

• There is an American National Standard for
  Information Interchange (ASCII) code chart for
  representing characters as binary values
• Table 6.1 in the text is not the normal way to
  represent the ASCII character values
• See ASCII code chart in Syllabus

11
Computer Architecture

• Processor Components

Data Bus
Instruction Register
Address
2
Mux
Decode
Program Counter
Arith Logic Unit
Accumulator
Memory Data and Instructions
12
Pippin Assembly Language

• Op Code Operand Action
• LOD W Load acc. from mem. loc. W
• ADD X Add mem. loc. X to acc.
• STO W Store acc. into mem. loc. W
• HLT None Halt

13
Pippin Machine Language

• Op Code Operand Action
• 00000100 10000000 Load acc. from mem. loc. 0
• 00000000 10000001 Add mem. loc. to acc. 1
• 00000101 10000000 Store acc. into mem. loc. 0
• 00001111 None Halt

14
Lets Go Try It on the Web Site

• Go to AE Online Web Site, Lab 6.1
• Enter instructions starting at 00000000
• LOD W
• ADD X
• STO W
• HLT ---
• Enter binary values in 10000000 10000001

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Lets Go Try It on the Web Site

• Change from Symbolic to Binary
• See the difference between
• assembly language for humans
• binary instructions for the computer
• Step or run through the program
• Reset the PC to 0 and step or run again
• What happened differently second time?

16
Homework

• Do Lab 6.1 for your study/practice
• Send me the answer to Part 4 Only!