Notes

CMPSC
OUR NUMBER SYSTEM:
- Our number system is called the DECIMAL system (base 10, 0-9)
- Multiplier base is 10 (DECimal)
- Each number is a digit position (553, each number is a digit position)
- Each position has its own exponent
- Right-most digit is the LSD (least significant digit)
- Left-most is the MSD (most significant digit)
- LSD always starts with an exponent of 0
- Add 1 to exponent for every number you move to the left (553 = 5 x 10^2 + 5 x 10^1 + 3 x 10^0)
COMPUTER BINARY:
- Detects if electricity is present on a wire
- Two symbols: 0 and 1 (binary)
- 0: Current present
-1: Current absent
- Multiplier base is 2 (BInary)
- Each position in a binary number is called a bit
- LSB (least significant bit) is raised to the exponent of 0
- Each position moved left, the exponent is raised by 1
- 1011 = 1 x 2^3 + 0 x 2^2 + 1 x 2^1 + 1 x 2^0 (8 + 0 + 2 + 1 = 11)
- Binary 1011 = Decimal 11
- When adding in binary, you carry the number over when you reach over the value of 1 instead of 10 for decimal
CONVERTING SYSTEMS (DECIMAL VS BINARY):
- 0 = 0
- 1 = 1
- 2 = 1 0 (carry the one)
- 3 = 1 1
- 4 = 1 0 0
- 5 = 1 0 1
- Keep adding one to count up (carry over when value equals 2 or higher) (11 + 1 = 1 2, carry the two, 2 0, carry the two, 1 0 0)
- When converting a binary number to a decimal number, multiply numbers starting from the right and going left by a multiple of two
BYTES:
- One unit of memory contains 8 bits
- 8 bits = 1 byte (can represent a number or letter)
- One unit can represent the number two by showing the number two (1 0 ) and putting before it 6 leading zeroes to fill the unit
- 255 is the largest number a computer can represent in one byte (relative value is 256)
LETTERS:
- Letters are also known as 'glyphs'
- Use symbols to represent sounds and shapes which form letters
- 65 in a memory cell is equivalent to the letter A
- Lowercase a is 97 bc it's a different shape than capitol A, so it gets its own number
ASCII:
- American Standard Code for Information Interchange