1. More on data storage and representation CSC 2001

2. Overview  Memory  Gates  Storage methods  Memory organization  Basic architecture  Long bit streams  Memory  Gates  Storage methods  Memory organization  Basic architecture  Long bit streams

3. Gates  … a device that produces the output of a Boolean operation when given the operation’s input values

4. AND, OR, XOR, & NOT gates

5. A simple flip-flop circuit

6. Setting the output of flip-flop

7. Storage techniques  core (direction of magnetic field)  capacitors (charged or discharged)  flash memory (trapped electrons in silicon dioxide) (full or empty)  core (direction of magnetic field)  capacitors (charged or discharged)  flash memory (trapped electrons in silicon dioxide) (full or empty)

8. Bits, bytes, and beyond 1 byte = 8 bits 1KB = 1024 (2 10 ) bytes 1MB = 1048576 (2 20 ) bytes 1GB = 1073741824 (2 30 ) bytes

9. Anatomy of a byte 0 1 0 1 1 0 1 0 high-order end low-order end most significant bitleast significant bit

10. Memory organization  memory cells  cells contain chunks of memory (often 1 byte)  have addresses (sequentially numbered)  information can span multiple cells  memory cells  cells contain chunks of memory (often 1 byte)  have addresses (sequentially numbered)  information can span multiple cells

11. Memory organization 10101010 11100011 11000011 00101010 01111011 00001101 01001101 01111011 11011101 10110110 00100100 00000000

12. ROM vs. RAM  Read Only Memory  Random Access Memory  Read Only Memory  Random Access Memory

13. Mass storage  Auxiliary storage devices  magnetic disks  hard drives, Zip disks  single vs. multiple disks  read/write head  tracks/cylinders/sectors  formatting  performance  seek time, latency, access time, transfer rate  Auxiliary storage devices  magnetic disks  hard drives, Zip disks  single vs. multiple disks  read/write head  tracks/cylinders/sectors  formatting  performance  seek time, latency, access time, transfer rate

14. Hard disks

15. More mass storage  Compact disks (CD-ROMs)  single spiral-shaped track  DVD-ROMs  multiple, semitransparent layers  Magnetic tape  high capacity, cheap, reliable  slow access time  Compact disks (CD-ROMs)  single spiral-shaped track  DVD-ROMs  multiple, semitransparent layers  Magnetic tape  high capacity, cheap, reliable  slow access time

16. File storage and retrieval  physical vs. logical records  knowing where to look  defragmentation  physical vs. logical records  knowing where to look  defragmentation

17. Basic architecture Input device Output device Auxiliary storage device Central Processing Unit Control Unit Arithmetic/logic unit Memory unit

18. Basic architecture Input device Output device Auxiliary storage device Central Processing Unit Control Unit Arithmetic/logic unit Memory unit Input device mouse, keyboard, modem

19. Basic architecture Input device Output device Auxiliary storage device Central Processing Unit Control Unit Arithmetic/logic unit Memory unit Output device screen, printer, modem

20. Basic architecture Input device Output device Auxiliary storage device Central Processing Unit Control Unit Arithmetic/logic unit Memory unit CPU Control Unit, ALU MHz (10 6 ), GHz (10 9 ) 32-bit, 64-bit

21. Basic architecture Input device Output device Auxiliary storage device Central Processing Unit Control Unit Arithmetic/logic unit Memory unit RAM bits, bytes (8 bits), MB (2 20 bytes), GB (2 30 bytes)

22. Basic architecture Input device Output device Auxiliary storage device Central Processing Unit Control Unit Arithmetic/logic unit Memory unit Aux storage unit MB, GB Zip disks, CD-ROM, DVD-ROM, tapes, hard drives

23. Basic architecture  We’ll return to this in chapter 2  For now, understand that the computer has to be able to store bits, that there are different kinds of memory, and different purposes for these different kinds of memory.  We’ll return to this in chapter 2  For now, understand that the computer has to be able to store bits, that there are different kinds of memory, and different purposes for these different kinds of memory.

24. Data representation  Translating data into bits  Characters and numbers  Large amount of data imply lots of bits.  Working with long strings of 0s and 1s quickly becomes cumbersome.  Translating data into bits  Characters and numbers  Large amount of data imply lots of bits.  Working with long strings of 0s and 1s quickly becomes cumbersome.

25. Dealing with long bit streams  Other (more concise) notation is useful  hexadecimal  base 16  need symbols for numbers 10-15 (because 10 16 = 16 10 )  Other (more concise) notation is useful  hexadecimal  base 16  need symbols for numbers 10-15 (because 10 16 = 16 10 )

26. Hexadecimal (0-7) base 2base 10base 16 000000 000111 001022 001133 010044 010155 011066 011177 base 2base 10base 16 000000 000111 001022 001133 010044 010155 011066 011177

27. Hexadecimal (8-15) base 2base 10base 16 100088 100199 101010A 101111B 110012C 110113D 111014E 111115F base 2base 10base 16 100088 100199 101010A 101111B 110012C 110113D 111014E 111115F

28. binary hex conversion Think in groups of four bits (start from right) Pad with 0 on left if needed 01001000 = 0100 1000 = 48 11011011 = 1101 1011 = DB AF = 1010 1111 = 10101111 E7 = 1110 0111 = 11100111 Think in groups of four bits (start from right) Pad with 0 on left if needed 01001000 = 0100 1000 = 48 11011011 = 1101 1011 = DB AF = 1010 1111 = 10101111 E7 = 1110 0111 = 11100111

29. practice problems 101101101101 A7D31C 101101101101 A7D31C