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Please fill out the 3x5 card
- Prior math/stats/comp sc coursework
- Any computer expertise
- Planned post-grad plans
- Hopes/fears about this class!
- Something I should know about you or might find interesting (helps me remember)
- A Password (make it one you will remember, but not one you also use for anything important. This is for web page access)
Computers - Basic Architecture
- Computers have:
- Storage (Memory)
- Connectivity (can be seen as an IO channel)
Using the Computer
Some simple binary arithmetic
- Why Binary?
- Why Decimal?
- People count by 10s
- Because we have ten fingers
- Computers count by ones
- Because magnetic storage media can electricity can be easily set to “on” and “off”
- Or 0 and 1
Bits and Bytes
- All of the data, programs, and circuitry are digital or binary in nature, meaning that they are comprised of the elements 0 and 1.
- This is somewhat different than standard (not digital or HD) radio, television, and vinyl or LP records, which operate on analog methods.
- Analog electronics means that devices use an electrical signal that has amplitude or magnitude instead of a stream of 0's and 1's.
- Why binary? Because the storage of information on magnetic media is accomplished by arranging bits of metallic oxide in one of two alignments, corresponding to 0 or 1.
- This allows for massive numbers of 0s and 1s to be stored in a very small space. This smallest unit of information (a 0 or a 1) is called a bit.
- Collections of bits can be organized into larger chunks.
- 4 bits = 1 nibble
- 8 bits = 2 nibbles = 1 byte
Counting in Base 2 (Binary)
Other Bases are useful as well
- A single byte, consisting of 8 bits can represent 256 different numbers
- The largest number represented by n bits is 2n-1
- Hence 28-1 = 255
- Including 0, that makes 256 different numbers
- These 256 numbers have been standardized to the ASCII character set. All PCs use the same number to represent the same character.
- This will expand with Unicode
What Do Computers Do?
- Computers add
- Computers Subtract
- Which is negative addition
- Computers multiply
- Which is adding multiple times
- Computers Divide
- Which is negative adding a bunch of times
- Computers do more complicated things –
- Square roots, power functions, exponentiation, logarithms
- All by numeric approximation – which is addition
- They move around the data that they add.
- That’s all…
- Functions as the arithmetic unit of the computer
- It operates according to it’s clock cycle
- A 1.8 GHz computer has a clock that cycles 1.8 billion times per second
- Adding Binary Numbers is Simple
- 3 Rules
- 0 + 0 = 0
- 1 + 0 = 1
- 1 + 1 = 10 ( = 0 and carry the 1 to the next higher column)
Graphic Representation of Addition
Does this look familiar
- Binary Addition is the electrical/electronic application of the “exclusive or” from logic
- Many numbers that are encountered frequently in computers arise from binary arithmetic
Get on the Bus
- Computers read data on the “buses” that the CPU has
- Two Buses of note
- Data Bus
- The data read into (or written from) the CPU or memory
- Address Bus
- The spot in memory to read from or write to
The Power of 2
More Powers of 2
And Even More Powers of 2
- So, in the end, we can see that computers simply move ad add 0’s and 1’s.
- And out of this, we can build incredibly rich and complex experiences
- Such as