ENGR 330: Todays Class

1
ENGR 330 Todays Class

• Class status
• Review program translation
• How subroutines work
• Final programming assignment
• Review Operating Systems hardware
• Application requirements and microprocessors

2
Class Status

• Program assignment 12/13
• Overall fine issues with format and commenting
• Full credit if it compiled and ran
• How did the overflow test work? / not work?
• Next couple of weeks
• Spot reviews on important topics
• C Programming
• Arrays, address calculations, structures
• Subroutines and recursion
• Problem solving with processors
• Establishing requirements
• Data representations
• Matching processors to requirements

3
Program Translation

• How does it really work?
• Translating common C elements
• Assignment statement
• Arithmetic calculation
• If statement
• While statement
• What about procedure/function calls?

4
How functions/procedures work

• The Stack
• Saved registers
• Return value, if any
• Arguments passed to the procedure
• Local variables
• What does this mean for compiling one?

5
Last Programming Assignment

• Read in a bunch of multi-digit numbers
• Store them in an array
• Print them out in the order they arrived
• Print them out again in the opposite order
• Use recursion
• Also, meet industry standards for code
  formatting

6
Program Formatting

• A REQUIREMENT for the last program
• Start with everything on the leftmost column
• Indent everything (statements and comments)
  inside a pair
• Statements that take more than one line
• Start the second line indented relative to the
  first
• IF statements and loops containing one statement
• Indent the statement covered by the IF or loop
• Commenting
• Start every function/procedure with a comment
• Comment every variable declaration
• Comment every major loop or IF
• Otherwise include a comment every 2 to 5
  statements

7
Looping with while

• printrest procedure, takes pointer at array
• While pointer gt 0
• Printf(d\n, pointer)
• pointer
• Return

8
Looping with Recursion

• printback procedure, takes pointer at array
• If pointer gt 0 Then
• Call printback(pointer 1)
• Printf(d\n, pointer)
• End If
• Return

9
What do Operating Systems do?

• The fundamental tasks
• P, M, I
• How has that affected processor design?

10
The Litany

• Process Management
• Need control user programs
• Feature Kernel mode/user mode
• Need let user programs run privileged software
• Feature TRAP programs that cause
  interrupt/exception
• I/O management
• Need let CPU get work done while waiting for I/O
• Feature Interrupts
• Feature DMA
• Need Block users from I/O
• Feature Kernel mode I/O access

• Memory Management
• Need keep programs from smashing each others
  RAM
• Feature access restrictions by different
  processes
• Feature memory mgmt can only be changed by the
  kernel
• Need efficient RAM allocation minimize
  fragmentation
• Feature Paging
• Need share limited RAM among numerous processes
• Feature virtual memory through page fault
  handling

11
Microprocessor Requirements, p. 1

• A. Large addressable RAM
• 1. Important video, scientific research, large
  scale simulations
• 2. Unimportant most other things
• B. Power consumption
• 1. Important portable devices, devices in
  confined spaces
• 2. Unimportant devices in open, climate
  controlled spaces
• C. Processor Speed
• 1. Important video, real time interactive
  systems, signal processing
• 2. Unimportant home appliances

12
Microprocessor Requirements, p. 2

• D. Cost per unit
• 1. Important commodity products USB hubs,
  singing greeting cards, etc.
• 2. Less important desktop computers,
  automobiles, fighter planes
• E. Scalability for growing calculation sizes
• 1. Same as for large RAM list above
• 2. Memory and processing power can usually trade
  off with one another
• a) You get by with less RAM with a faster
  processor (in theory at least)
• 3. Scalability in processors assumes
  multiprocessor support

13
Microprocessor Requirements, p. 3

• F. Software compatibility with (x) software
• 1. Important application depends on software
  that only runs on Windows, or Solaris/SPARC, or
  something
• 2. Unimportant application will be built to
  match the best CPU for the problem
• G. Signal processing performance
• 1. Important cell phones, radars, software
  radios, MP3 players
• 2. Unimportant applications without real time
  data streams to process
• H. Graphics processing performance
• 1. Important video playback, video editing,
  image editing
• 2. Unimportant applications without large
  shallow matrices to process

14
Thats it.

• Questions?
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