Where Have We Been Where Are We Going

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Where Have We Been?Where Are We Going?

• CPSC 120
• Principles of Computer Science
• October 23, 2007

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Programming is

• About details, details, details
• Tedious, frustrating when it is not working
• Addictive, it gives immediate feedback
• Fun, if you are organized
• Coding/Decoding
• Algorithms - PBASIC - BS2 Codes - Movement
• Where hardware meets software
• Learning another language
• An art form at the higher levels

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Our Course Themes

• Complexity and Structure Transistors to CPU,
  PBASIC subroutines, mental images of a program
  execution sequence
• Encoding and Decoding PBASIC, ASCII,
  if ( irDetectLeft 0 ) THEN GOSUB Veer_Right
• Hardware and Software Robots involve both these
  in large measure. Both are necessary.
• Theory and Application IR detection,
  Electronics, LEDs, DOLOOP UNTIL (qti 0110)
• Local versus Global New Theme! Computation
  taking place at my PC, IPod, etc versus on a
  remote machine.

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Our BS2 was about as simple a CPU as we could
hope to program. It did allow direct control of
digital values on I/O pins. It is very limited
in terms of storage (none), Internet access
(none), human interface (only via Basic Editor),
etc.
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Compare to this Computer Motherboard
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A Diagram for a Laptop Computer
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Some History Back to the Future

• Very early computer systems had one shared CPU
  with (dumb) ASCII terminals
• Low cost microcomputers allowed a single personal
  computer for single user, a PC.
• Most PC computer programs used only local data on
  a hard disk, connected to a printer.
• Programs were about mundane computations
  financials, paychecks, inventory, etc.
• Sharing data was necessary so servers were
  connected via networks to many PCs.
• The Internet allowed a world-wide integrated
  system of sharing data and communications.

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Local PC applications

• Early use for PCs concentrated on financial,
  business, and science applications.
• Text editors such as Write, WordPerfect, Word,
  etc came to be a standard office feature.
• Another application was the spreadsheet, a visual
  way to do numerical computations based on an
  array of data cells.
• Spreadsheets allow us to control complexity
  through traditional row and column structure,
  (ledgers) encode both data and programs into a
  single document, but requires us to understand
  the basic math involved, at least.

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View of a Spreadsheet (partial)
Notice we have a 2-D collection of cells
containing both numbers and text. We might want
to calculate the total number of students
enrolled by adding the right column. Later, if
we find some students added or dropped courses,
we have to do the additions again. A spreadsheet
allows almost instantaneous updates of sums,
averages, etc when data is changed.
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Coming attractions

• Collect some data so we have something to enter
  into a spreadsheet.
• Learn the basics of a spreadsheet program to
  organize, manipulate, and make charts from our
  data.
• Understand how to integrate our charts into other
  office tools, such as MS Word or Open Office.
• Move on to more global ways to present ourselves
  and our work on the Internet.