1. UMBC CMSC 104 – Section 01, Fall 2016 1

2. UMBC CMSC 104, Section 01 - Fall 2016  Don’t see a Linux VM in VMWare on your lab machine? Try a different computer!  If you plan to come to my office during office hours, please e-mail me first and let me know.  Need a volunteer to stay 5-10 minutes after class – need to verify project submission system is working.  Grades list on website updated Saturday with latest class roster. 2

3. UMBC CMSC 104, Section 01 - Fall 2016  A programmable machine  Characteristics:  Responds to a specific set of instructions in a well- defined manner  Can execute a pre-recorded list of instructions (a program)  Modern computers are electronic and digital 3

4. UMBC CMSC 104, Section 01 - Fall 2016  Mainframes  Servers  Personal Computers  Desktop  Laptop  Tablets & Smartphones & Smart Watches  Lots of other stuff!  Modern Televisions  Game Systems  Printers  Really, any kind of modern programmable machine 4

5. UMBC CMSC 104, Section 01 - Fall 2016  1960s: The Mainframe Era  One “big, powerful” computer  1970s: Rise of the Microprocessor  Mainframe still center stage, but…  First personal computers begin to appear  1980s & 1990s: PC is king  “A PC on every desk”  2000s & 2010s: Rise of Mobile & The Web  Phones & Tablets > PCs  “The Cloud” 5 BIG SMALL

6. UMBC CMSC 104, Section 01 - Fall 2016  We tend to use modern computers for information & content creation and consumption  Content consumption is easy on mobile devices  Content creation on mobile devices is more difficult ▪ PCs still king of creation; information input is generally easier  In this class, we will primarily focus on PCs  But C code runs on devices of all shapes and sizes! 6

7. UMBC CMSC 104, Section 01 - Fall 2016  Central Processing Unit (CPU)  Arithmetic Logic Unit (ALU)  Graphics Processing Unit (GPU)  Main Memory (RAM)  Secondary Storage Media (hard disk)  Input devices (mouse, keyboard)  Output devices (monitor, speakers) 7

8. UMBC CMSC 104, Section 01 - Fall 2016  Central Processing Unit  The “brain” of the computer  Controls all other computer functions  In PCs (personal computers) also called the microprocessor or simply processor. 8

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11. UMBC CMSC 104, Section 01 - Fall 2016  Some computers (especially servers) can have multiple CPUs  Many modern computers have CPUs with multiple cores. This is essentially multiple CPUs on a single chip.  Makes & Models  Intel ▪ Desktop: Core i7, i5, i3, Celeron, Pentium ▪ Server: Xeon, Itanium  AMD (Advanced Micro Devices) ▪ Desktop: FX, Athlon, A-Series, Sempron ▪ Server: Opteron  Many more… 11

12. UMBC CMSC 104, Section 01 - Fall 2016  Speeds measured in Hertz (Hz)  Hz = Cycle Per Second  1 Megahertz (MHz) = 1 Million Hz  1 Gigahertz (GHz) = 1 Billion Hz  A typical modern desktop CPU is 2.5- 4GHz  A quad-core 4 GHz CPU can do 4x 4GHz simultaneous operations  This is NOT the same thing as a 16 GHz CPU. 12

13. UMBC CMSC 104, Section 01 - Fall 2016  Arithmetic Logic Unit  Generally incorporated into the CPU in modern PCs  Responsible for arithmetic calculations  Addition (subtraction)  Multiplication (division)  Contains decision mechanisms, such as comparison of two memory units 13

14. UMBC CMSC 104, Section 01 - Fall 2016  Graphics Processing Unit  Separate processor specially optimized for graphic operations  Typically tons of cores  Allows CPU to offload some graphics processing routines so it can focus on other things  May be integrated into a modern CPU, or entirely separate 14

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16. UMBC CMSC 104, Section 01 - Fall 2016 16 Main memory holds information such as computer programs or numeric data. Also known as RAM (Random Access Memory) More in this shortly… Made up of capacitors. Capacitors have two states: Charged (or on or 1 or set) Not charged (or off or 0 or reset or cleared)

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18. UMBC CMSC 104, Section 01 - Fall 2016 18 Memory is divided into cells, where each cell contains 8 bits (a 1 or a 0). Eight bits is called a byte. Each of these cells is uniquely numbered. The number associated with a cell is known as its address. Main memory is volatile storage. That is, if power is lost, the information in main memory is lost.

19. UMBC CMSC 104, Section 01 - Fall 2016 19 Other computer components can o get the information held at a particular address in memory, known as a READ, o store information at a particular address in memory, known as a WRITE. Writing to a memory location alters its contents. Reading from a memory location does not alter its contents.

20. UMBC CMSC 104, Section 01 - Fall 2016 20 All addresses in memory can be accessed in the same amount of time. We do not have to start at address 0 and read everything until we get to the address we really want (sequential access). We can go directly to the address we want and access the data (direct or random access). That is why we call main memory RAM (Random Access Memory).

21. UMBC CMSC 104, Section 01 - Fall 2016  Sizes measured in bytes  1 Megabyte (MB) is approximately 1 million bytes  1 Gigabyte (GB) is approximately 1 billion bytes  A typical modern desktop PC has 4-16GB of RAM  Servers typically have more: 32-256GB of RAM  RAM is also has speed ratings  Beyond the scope of this course 21

22. UMBC CMSC 104, Section 01 - Fall 2016  Disks -- floppy, hard, removable (random access)  Tapes (sequential access)  CDs/DVDs/Blu-Ray (random access)  Secondary storage media store files that contain  computer programs  data  other types of information  This type of storage is called persistent (permanent) storage because it is non-volatile. 22

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28. UMBC CMSC 104, Section 01 - Fall 2016  Like RAM, secondary storage is typically measured in bytes  A terabyte (TB) is approximately 1000 GB  A typical desktop PC sizes  Hard Disk (traditional magnetic): 1-4 TB  Solid State Drive: 256GB – 1TB  DVD: 4.7 or 8.5 GB  Blu Ray: 25GB or 50GB 28

29. UMBC CMSC 104, Section 01 - Fall 2016  In the classic sense, the term “memory” refers to “main memory”, or RAM  In the modern sense, the term “memory” sometimes refers to secondary storage  e.g. some people say their phone has “64 GB memory”  To avoid confusion, it’s best to be specific  Say “RAM” or “main memory” when referring to RAM  Say “storage” when referring to secondary storage 29

30. UMBC CMSC 104, Section 01 - Fall 2016  Information input and output is handled by I/O (input/output) devices.  More generally, these devices are known as peripheral devices.  Examples:  monitor  keyboard  mouse  CD or DVD drive  printer  scanner 30

31. UMBC CMSC 104, Section 01 - Fall 2016  Computer components are connected by a bus.  A bus is a wire or a group of wires that carry control signals and data between components.  A bus can be parallel or serial  A parallel bus contains a separate wire per bit transferred  A serial bus has a single wire where bits are sent in sequence 31

32. UMBC CMSC 104, Section 01 - Fall 2016 32 CPU RAM HDD/SSD/BD GPU I/O Devices

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34. UMBC CMSC 104, Section 01 - Fall 2016  Discussed briefly earlier  Smallest data item in a computer  Short for Binary Digit  Is either “on” or “off”  Represented as 1 or 0, respectively  Abbreviated with a lowercase b  “It’s all zeros and ones” 34

35. UMBC CMSC 104, Section 01 - Fall 2016  Discussed briefly earlier  Consists of 8 bits  Historically, this was machine-dependent, however the de-facto standard became 8 bits  Smallest addressable unit of memory in a modern computer  You can’t request the value of a single bit in memory. The smallest you can get is a byte.  Term coined in 1956 during the design phase for the IBM 7030  Abbreviated with an uppercase B 35

36. UMBC CMSC 104, Section 01 - Fall 2016  Under the International System of Units (SI), the prefix kilo means 1000 (10 3 )  In computer storage terms, a kilobyte (KB) typically refers to 1024 bytes (2 10 ) as an approximation.  To address this ambiguity, the new prefix kibi was created in 1998 to refer to 2 10. Thus a Kibibyte (KiB) represents 1024 bytes.  In practice, nothing has changed, and KB is still widely used to represent 1024 bytes  Notable exception: macOS since 10.6 uses KB as 1000 bytes. 36

37. UMBC CMSC 104, Section 01 - Fall 2016 37 UnitBytesWhich is about… 1 kilobyte (KB)1024 bytes10 3 bytes (exactly) 1 megabyte (MB)1024 kilobytes10 6 bytes 1 gigabyte (GB)1024 megabytes10 9 bytes 1 terabyte (TB)1024 gigabytes10 12 bytes 1 petabyte (PB)1024 terabytes10 15 bytes 1 exabyte (EB)1024 petabytes10 18 bytes 1 zettabyte (ZB)1024 exabytes10 21 bytes

38. UMBC CMSC 104, Section 01 - Fall 2016  Consist of  Numbers (0-9)  Letters (a-z, A-Z)  Symbols (!, @, #, $, etc.)  Much easier to deal with than bits & bytes  Easily mapped to 8-, 16-, or 32-bits using a character set  Common simple 8-bit standard character set is ASCII (American Standard Code for Information Interchange) 38

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40. UMBC CMSC 104, Section 01 - Fall 2016  A persisted sequence of bytes  …that’s pretty much it.  More later. 40

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