Monday, July 15, 2002		ITerminology

SP

Short for stack page, a reserved space in Windows of 4K of memory that a 32-bit device driver uses to hold data and instructions as it works. The default setting in Windows sets one stack page for device drivers and two spare pages for temporary allocations. The spare pages are called MinSPs, short for minimum stack pages.

SPI

Short for serial peripheral interface, a full-duplex synchronous serial interface for connecting low to medium-bandwidth external devices using four wires. SPI devices communicate using a master/slave relationship over two data lines and two control lines:

· Master Out Slave In (MOSI) - supplies the output data from the master to the inputs of the slaves.

· Master In Slave Out (MISO) - supplies the output data from a slave to the input of the master. It is important to note that there can be no more than one slave that is transmitting data during any particular transfer.

· Serial Clock (SCLK) - a control line driven by the master, regulating the flow of data bits.

· Slave Select (SS) - a control line that allows slaves to be turned on and off with hardware control.

Dynamic DNS

Short for dynamic Domain Name System, a method of keeping a domain name linked to a changing IP address as not all computers use static IP addresses. Typically, when a user connects to the Internet, the user's ISP assigns an unused IP address from a pool of IP addresses, and this address is used only for the duration of that specific connection. This method of dynamically assigning addresses extends the usable pool of available IP addresses. A dynamic DNS service provider uses a special program that runs on the user's computer, contacting the DNS service each time the IP address provided by the ISP changes and subsequently updating the DNS database to reflect the change in IP address. In this way, even though a domain name's IP address will change often, other users do not have to know the changed IP address in order to connect with the other computer.