Data Storage(I)-計算機概論筆記

一定愛配于天立教授開放課程食用:課程連結

Data Storage(I)

Binary world

• Simple, logical and unambiguous
• Boolen operation and gates
  1. AND:
  2. OR:
  3. Exclusive OR(XOR):
  4. NOT:

Flip-Flop(正反器)

• Purpose -> To store 0/1
• 2 inputs
• One -> set 0
• The other -> set 1
• It will preserve 0/1 if there is no inputs
• 

  • Simple SR Flip-Flop Circuit

  • Another Simple SR Flip-Flop Circuit

Hexadecimal(Hex，十六進位)

• Reason of using Hex
  1. Binary is too long for human to remember
  2. Binary to Hex is straightforward
• 

Main memory cell

• 8 bits -> 1 cell -> 1 byte
• 

Memory

• One dimensional
• Random accessible
• Access the content via the address
• 

Memory techniques

• Random access memory (Ram): Memory in which individual cells can be easily randomly accessed.
  1. Type: Static Memory(SRAM), Dynamic Memory(DRAM), Synchronous DRAM(SDRAM)
  2. Double Date Rate(DDR)->Faster when reading data
  3. Dual/Triple channel
• 1. Kilobyte: = 1024 bytes bytes
  2. Megabyte: = 1038576 bytes bytes
  3. Gigabyte: = 1073741824 bytes bytes
  4. Gigabyte: = 1073741824 bytes bytes

Mass Storage

• Properties:
  1. Larger capacity
  2. Less volatility
  3. Slower
  4. On-line or off-line
• Types:
  1. Magnetic systems(HDD，Floppy Disk)
  2. Optical systems(CD，DVD)
  3. Flash drives(SSD)
• Magnetic storage:
  1. 
  2. 
  3. Access time = seek time(To reach the right track) + rotation delay(latency time，To reahc the right sector)
  4. Transfer rate(SATA)
• Optical storage
  1. 
• Physical and logical records
  1. 
• Buffer(緩衝區)
  1. Purpose: To synchronize different read/write mechanisms and rates
  2. An area used to temporarily store data

Representing text

• ASCII: 7 bits (or 8 bits starts with 0)
• Unicode: 16 bits
• ISO: 32 bits

Representing numbers

• 901 (decimal):

• 11 (binary):

• From binary to decimal

• From decimal to binary

Representing img

• Bit map techniques:
  1. Pixel: the element of a picture
  2. Colors: RGB，HSV，etc.
• Vector techniques:
  1. Properties: Scalable
  2. Truetype，Postscript，SVG(scalable vector graphic)

Representing sound

• Sampling
  1. Sample rate and bit resolution
  2. Bit rate(sampling rate bit resolution)
• MIDI(synthesis)
  1. A protocol designed for recording and playing back music on digital synthesizers that is supported by many makes of personal computer sound cards

Binary system revisited

• Addition
  1. 0+0=0
  2. 1+0=1，0+1=1
  3. 1+1=10
• Subtraction
  1. Define negative numbers first(Two's Complement Notation)

Two's complement notation and encoding

• 
• Encoding(method 1): After finishing the process，you can directly do the addition and get the right answer
• Encoding(method 2): Do it as usual binary way
• Encoding(method 3):

Excess notation

• 
• Addition: After the calculation, u have to add 4 to get the right answer ## Overflow Using the table from Two's complement:
• Occurs when the result is out of range(not in table)
• Addition of two positive numbers -> 2+3=5 -3(mod 8)
• Addition of two negative numbers -> (-2)+(-3)=-5 -3(mod 8)