Online Computer Terms Dictionary - S

Serial Communications Interface

UART

Serial Interface Adaptor

(SIA) The Ethernet driver chip used on a Filtabyte Ethernet card.

serial IO chip

UART

serialise

<programming> To represent an arbitrarily complex data structure in a location-independent way so that it can be communicated or stored elsewhere.

For example, an object representing a time, with attributes for year, month, timezone, etc., could be serialised as the string "2002-02-24T14:33:52-0800", or an XML element "<dateobj year='2002' month='02' day='24' hour='14' minute='33' second='52' timezone='-0800' />", or as a binary string.

As well as providing an external data representation (e.g. representing an integer as a string of ASCII digits) and marshalling components into a single block of data, a serialisation algorithm needs to follow pointers to include objects referred to by the initial object. This is further complicated by the possible presence of cycles in the object graph.

It should be possible to store the serialised representation on disk, or transmit it across a network, and then restore it as an object (graph) that is the same as the original.

(2001-09-28)

serialize

serialise

serial line

Wires which connect two serial ports carrying serial data consisting of sequential bits represented by one of two voltages.

A common electrical specification for the signals on a serial line is RS-423.

ftp://ftp.acorn.co.uk/pub/documents/appnotes/231-245/234.ps.

(1995-02-02)

Serial Line Internet Protocol

<communications, protocol> (SLIP) Software allowing the Internet Protocol (IP), normally used on Ethernet, to be used over a serial line, e.g. an EIA-232 serial port connected to a modem. It is defined in RFC 1055.

SLIP modifies a standard Internet datagram by appending a special SLIP END character to it, which allows datagrams to be distinguished as separate. SLIP requires a port configuration of 8 data bits, no parity, and EIA or hardware flow control. SLIP does not provide error detection, being reliant on other high-layer protocols for this. Over a particularly error-prone dial-up link therefore, SLIP on its own would not be satisfactory.

A SLIP connection needs to have its IP address configuration set each time before it is established whereas Point-to-Point Protocol (PPP) can determine it automatically once it has started.

See also SLiRP.

(1995-04-30)

Serial Line IP

(SLIP) Serial Line Internet Protocol.

Serial Peripheral Interface

<communications, hardware> (SPI) A serial interface in which a master device supplies clock pulses to exchanges data serially with a slave over two data wires (Master-Slave and Slave-Master). This term probably originated with Motorola in about 1979 with their first all-in-one microcontroller.

(2003-07-13)

serial port

<hardware, communications> (Or "com port") A connector on a computer to which you can attach a serial line connected to peripherals which communicate using a serial (bit-stream) protocol. The most common type of serial port is a 25-pin D-type connector carrying EIA-232 signals. Smaller connectors (e.g. 9-pin D-type) carrying a subset of EIA-232 are often used on personal computers. The serial port is usually connected to an integrated circuit called a UART which handles the conversion between serial and parallel data.

In the days before bit-mapped displays, and today on multi-user systems, the serial port was used to connect one or more terminals (teletypewriters or VDUs), printers, modems and other serial peripherals. Two computers connected together via their serial ports, possibly via modems, can communicate using a protocol such as UUCP or CU or SLIP.

(1995-01-12)

Serial Presence Detect

presence detect

serial processing

sequential processing

Serial Storage Architecture

(SSA) IBM's proposed ANSI standard for a standard high-speed interface to disk clusters and arrays. SSA allows full-duplex packet multiplexed serial data transfers at rates of 20Mb/sec in each direction.

According to John Taylor, programme manager at IBM's Storage Division at Havant, SSA will be used in arrays of discs working with high-end computers ranging from mainframes down to LAN servers. Taylor said that SSA differs from the IEEE proposed P1394 serial interface specification in its ability to offer simultaneous multiplexed transfers from more than one disk or array. IBM also supports the P1394 standard which will be used primarily by desktop PCs for multimedia applications.

SSA has received backing from a number of companies including connector makers Molex, ITT Cannon and AMP, disk drive makers Conner and Western Digital and RAID array suppliers like Dynatech and NCR. IBM expects to see the first SSA products released at Comdex in Autumn 1994 but it will be 1995 before the products ship in volume.

Under an agreement signed with ASIC maker and ARM licencee VLSI Technology, IBM will use ARM-based chips made by VLSI to implement the SSA interface and VLSI will make these cores available to third parties as one of its Functional System Blocks.