1. Lecture on Central Process Unit (CPU)

2. Central Processing Unit
Brain of any “processing” device
What are the processing devices?
Computers, cell phones, game consoles, TVs, refrigerators, … just about any electronics
CPU is a conceptually simple, but a highly complex circuitry that responds to executable inputs (i.e., program instructions).

4. Intel Pentium 4 CPU

5. Main Components of CPU
Control unit: Directs all program instructions. It does not actually execute instructions, but makes other parts to do so.
Arithmetic logic unit: It executes all arithmetic and logical operations. Commonly known as ALU.
Registers: Small memory blocks (a few kilo bytes) inside CPU to store intermediate computation results or addresses during processing
Caches: Larger memory blocks (a few mega bytes) inside CPU to store data during processing

6. (Outlook, Safari, iTune)
How Does Computer Work?
Application software is written in a human readable form, normally stored in hard disk.
To run application software, OS retrieves it first from hard disk, and translates it to a machine readable form. Then, OS instructs CPU how to run it.
CPU interfaces with rest of computing hardware and together executes the machine readable code from OS.
Computing hardware is controlled by CPU.
Application Software
(Outlook, Safari, iTune)
Operating System
(Windows, MacOS)
CPU
(Intel, AMD)
Computing Hardware
(Dell, IBM, Apple)

7. Computing Hardware CPU: Main controller
INPUT
DEVICE
OUTPUT
DEVICE
CPU
HARD DISK
MEMORY
MOTHERBOARD
CPU: Main controller
Memory: All instructions and data are entered into CPU through memory
Input device: Keyboard, mouse, touch screen, etc.
Output device: Display terminal, printer, speaker etc.
Hard disk: Mass storage for all data, program, and information

8. Mother of All Boards = “Motherboard”
CPU

9. Addressing
In computer, all storage devices (memories and hard disk) are given unique addresses.
Main memory is fast and can interact with CPU directly. But its size is limited (a few giga bytes) and cannot store all of the data or programs.
Data or program is loaded into main memory when needed by CPU. Otherwise, it is stored in hard disk. This process is called “swapping.”

10. What Happens When You Turn on Computer?
When you turn on the computer, the hardware starts.
With the power on, the CPU starts executing instruction at certain memory location. This is the “BIOS.”
The BIOS contains the start-up programs such as device detection, initialize background programs (demons), and the start of OS.
Critical part of OS (i.e., part needed by all programs) is permanently loaded into the main memory. This part is called the kernel.
Now the computer is ready to accept any command that the user enters.

11. Scheduling Queues Scheduling queues is a main functions of OS.
Job queue: Set of all processes
Ready queue: Set of all processes residing in main memory, ready and waiting to execute
Device queue: Set of processes waiting for I/O device

12. Interactions with Memory
CPU
Memory
Address Lines
Data Lines
Read Line
Write Line

13. CPU Execution Cycle Obtain instruction from program storage
Fetch
Decode
Operand
Execute
Result
Store
Next
Obtain instruction from program storage
Determine required actions and instruction size
Locate and obtain operand data
Compute result value or status
Deposit results in storage for later use
Determine successor instruction; can generally be combined w/ Decode

14. Thread Thread: Schedulable stream of controls
Defined by CPU
Suspend: Save register values in memory
Resume: Restore registers from memory
Multiple threads can execute independently
They can run in parallel on multiple CPUs...
Or interleaved on a single CPU
Each thread must have its own control stack.

15. Single and Multithreaded Processes

16. Two Threads Sharing a CPU
concept
reality
context switch

17. Speed How fast the CPU can execute instructions
Limited by many factors
Speed of electronic circuits in CPU
Speed of memory access
Speed of hard disk
Efficiency of OS
Efficiency of application software

18. Processor Speed

19. CPU
high speed
slower I/O devices

20. PCI Bus Peripheral Connection Interface South Bridge architecture
66 MHz, 64-bit, 512 MB/second
Shared bus with arbitration

21. PCI Express North Bridge architecture
Switched, point- to-point connection
Data rate up to 4 GB/second