Kernels and Routines

1. Kernels and Routines Dr. Harold D. Camp IT 212 002 29 March 2007

2. Homework 6 • For an application that maintains your checkbook, build three flow charts • Kernel flow chart showing the process of balancing a check book • Routine flow chart showing the accessing of data from a hard drive (that is called from the Kernel)

3. Flow Charting Call Routine Function Decision Start/Stop Input or Output

4. Sample Flow Diagram Start/Stop OS Supplied Routines Read Balance, Type, Amount If Type Is Debit Kernel Call Debit Call Credit Kernel Specific Routines Stop

5. Sample Flow Diagram Debit Start/Stop NBal = Bal - Amt Read Balance, Type, Amount If NBal > 0 Call Dispense If Type Is Debit Call Debit Write NBal Call Reject Call Credit Return Stop

6. So, Check Book Kernel • Checkbook Activities • Debit • Credit • Balance • Does my balance agree with Bank’s balance? • Routines (One Kernel Specific and One OS Required) • DLL • API • Registry

7. Dynamic Link Library (DLL) • A library of executable functions or data that can be used by a Windows application • A DLL provides one or more functions • A program accesses the functions by creating a static or a dynamic link to the DLL • A static link remains constant during program execution • A dynamic link is created by the program as needed • A DLL can be used by several applications at the same time • Some DLLs are provided with the Windows operating system and available for any Windows application • Other DLLs are written for a particular application and are loaded with the application

8. Dynamic Link Library (DLL) • DLL is Microsoft's implementation of the shared library concept in the Microsoft Windows and OS/2 operating systems • Usually have the file extension DLL, OCX (for libraries containing ActiveX controls), or DRV (for legacy system drivers) • DLL file formats are the same as for Windows EXE files • Portable Executable (PE) for 32-bit Windows • New Executable (NE) for 16-bit Windows • DLLs can contain code, data, and resources, in any combination.

9. Dynamic Link Library (DLL) http://www.eldos.com/documentation/solfs/dll_functions_list.html

10. Application Program Interface (API) • A set of routines, protocols, and tools for building software applications • A good API makes it easier to develop a program by providing all the building blocks • A programmer puts the blocks together • Most operating environments, such as MS-Windows, provide an API • Programmers can write applications consistent with the operating environment • Guarantee that all programs using a common API will have similar interfaces • Examples?

11. Registry • A database used by the Windows operating system to store configuration information • The Registry consists of the following major sections: • Roots - file associations and OLE information • Users Preferences - all preferences set for current user • User Information - all the current user information for each user of the system • Local Machine Settings - settings for hardware, operating system, and installed applications • Current Configuration - settings for the display and printers and other devices • Dynamic Data - performance data • Most Windows applications write data to the Registry • You can edit the Registry directly by using the Registry Editor • regedit.exe provided with the operating system • Errors in the Registry could disable your computer.

12. In Class Example • Digital Clock Kernel • Kernel Specific Routines • OS Specific Routines • Be careful here • Must use API, DLL, Registry

13. Bandwidth and Moving Data,A/D Converters, UPS, Ports, SATA, USB

14. How Bandwidth Moves Data • In Class Discussion

15. Analog to Digital Converters • Signals in the real world are analog • Light, sound, you name it • Must be converted into digital, using a circuit called ADC (Analog-to-Digital Converter), before they can be manipulated by digital equipment

16. Analog to Digital Converters • Signals in the real world are analog • Light, sound, you name it • Must be converted into digital, using a circuit called ADC (Analog-to-Digital Converter), before they can be manipulated by digital equipment

17. Digital to Analog Conversion

18. Analog to Digital Converters • In Class Discussion • http://electronics.howstuffworks.com/analog-digital4.htm

19. Uninterruptable Power Supplies • http://www.aeceuro.co.uk/upsAnimation.asp • Voltage surges and spikes - Times when the voltage on the line is greater than it should be • Voltage sags - Times when the voltage on the line is less than it should be • Total power failure - Times when a line goes down or a fuse blows somewhere on the grid or in the building • Frequency differences - Times when the power is oscillating at something other than 60 Hertz

20. Ports • A port serves as an interface between the computer and other computers or devices • Physically, a port is a specialized outlet to which a plug or cable connects • Serial ports send and receive one bit at a time via a single wire pair (Ground and +/-) • Parallel ports send multiple bits at the same time over several sets of wires

21. Ports • After ports are connected, they typically require "handshaking," • similar to negotiation, where transfer type, transfer rate, and other necessary information is shared before data are sent • Hot-pluggable ports can be connected while equipment is running • Hot-plugging a keyboard on many computer models can cause permanent damage to the motherboard • Plug-and-play ports are designed so that the connected devices automatically start handshaking as soon as the hot-plugging is done • USB ports and FireWire ports are plug-and-play • At times, special software (driver) must be loaded to allow communication (correct signals) for certain devices • A driver doesn't change the port, • Rather a driver uses the port signal to control the attached device

22. Ports • Currently (2006) manufacturers have nearly standardized on colors associated with ports on personal computers, although there are no guarantees. The following is a short list: • Orange, purple, or Grey: Keyboard PS/2 • Green: Mouse PS/2 • Blue or magenta: Parallel Printer DB-25 • Amber: Serial DB-25 or DB-9 • Pastel pink: Microphone 1/4" stereo (TSR) Minijack • Pastel green: Speaker 1/4" stereo (TSR) Minijack

23. Ports http://www.cyberwalker.net/connectors

24. Serial Advanced Technology Attachment (SATA) • SATA • A computer bus technology primarily designed for transfer of data to and from hard disks and optical drives • Designed as a successor to the legacy Advanced Technology Attachment standard (ATA) • Expected to replace the older Parallel ATA technology • Serial ATA adapters and devices communicate over a high-speed serial link • Architecture • Two pairs of (unidirectional) signal wires • Low Voltage Differential Signaling (LVDS) • 1.5 Gbit/s and up • Above the SATA physical level are the link level and transport level • Convert data into discrete ordered packets • The application level generates read/write PIO and DMA requests • Each SATA/device has a link to a SATA host-port, with no sharing of cable or bandwidth between devices

25. Serial Advanced Technology Attachment (SATA)

26. Universal Serial Bus • A serial bus standard to interface devices • Designed for personal computers • Has become commonplace on handheld devices • Devised to help retire all serial and parallel ports on personal computers • A USB system has an asymmetric design • Host controller • Multiple daisy-chained peripheral devices • Additional USB hubs may be included in the chain • Allows branching into a tree structure, subject to a limit of 5 levels of branching per controller • No more than 127 devices • USB's ability to daisy-chain devices • Led to computers shipped only two USB ports • To reduce the need for USB hubs, desktop computers now come with more USB ports • Up to half of them on the front panel to facilitate temporary connection of portable devices

27. Universal Serial Bus • USB designed to allow peripherals to be connected without expansion cards • And to improve plug-and-play capabilities by allowing devices to be hot-swapped • Connected or disconnected without powering down or rebooting the computer • When a device is first connected, the host enumerates and recognizes it, and loads the device driver it needs • USB can connect peripherals • Such as mouse devices, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, external storage, networking components, etc. • For many devices such as scanners and digital cameras, USB has become the standard connection method • USB is also used extensively to connect non-networked printers, replacing the parallel ports that had previously been in wide use

28. Universal Serial Bus Features • The computer acts as the host. • Up to 127 devices can connect to the host, either directly or by way of USB hubs. • Individual USB cables can run as long as 5 meters; with hubs, devices can be up to 30 meters (six cables' worth) away from the host. • With USB 2.,the bus has a maximum data rate of 480 megabits per second. • A USB cable has two wires for power (+5 volts and ground) and a twisted pair of wires to carry the data. • On the power wires, the computer can supply up to 500 milliamps of power at 5 volts. • Low-power devices (such as mice) can draw their power directly from the bus. High-power devices (such as printers) have their own power supplies and draw minimal power from the bus. Hubs can have their own power supplies to provide power to devices connected to the hub. • USB devices are hot-swappable, meaning you can plug them into the bus and unplug them any time. • Many USB devices can be put to sleep by the host computer when the computer enters a power-saving mode. • http://computer.howstuffworks.com/usb.htm