Data Dictionary - S (continued)


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  • Satallite Computer
  • Scrap
  • Scratchpad
  • Secondary Storage
  • Security Kernel
  • Serial Communications
  • Settling Time
  • Sign Bit
  • SIMM
  • Single-Board Computer
  • Small Model
  • Smart Terminal


Satellite Computer
A computer that is connected to another computer, with which it interacts over a communications link. As its name indicates, a satellite computer is of lesser “stature” than the main, or host computer; the host controls either the satellite itself or the tasks the satellite performs.

An application or system file maintained for storage of document data that has been marked for movement, copying, or excision.

A temporary storage area used for calculations, data, and other work in progress. In reference to a microprocessor, scratchpad refers to a special high-speed memory circuit used to hold small items of data for rapid retrieval.

Secondary Storage
Any data storage medium other than a computer’s random access memory – typically, tapes or disk.

Security Kernel
An operating-system kernel that is protected from unauthorized use.

Serial Communications
The transmission of information between computers or between computers and peripheral devices one bit at a time over a single line. Serial communications can be synchronous (controlled by some time standard such as a clock) or asynchronous (managed by the exchange of control signals that govern the flow of information). An important aspect of serial communications – and a potential source of difficulty – is that both sender and receiver must use the same baud rate, parity, and control information.

Settling Time
The time required for a disk drive’s read/write head to stabilize over a new site after being moved from another position over the disk.

Sign Bit
The most significant (leftmost) bit of a number field, usually set to 1 if the number is negative. When an 8-bit value is added to a 16-bit value using signed arithmetic, the microprocessor propagates the sign bit through the high order half of the 16-bit register holding the 8-bit value in a process called sign extension or sign propagation.

Abbreviation for single in-line memory module, a small circuit board designed to accommodate surface-mount memory chips. See the illustration. SIMMs use less board space and are more compact than more conventional memory-mounting hardware.

Single-Board Computer
A computer that occupies single circuit board, usually with no facility for installing additional circuit boards. Industrial machinery often uses an on-board computer to control its operation; this computer is usually a single-board computer.

Small Model
A memory model of the Intel 80*86 processor family. The small model allows only 64 kilobytes (KB) for code and only 64 KB for data.

Smart Terminal
A terminal that contains a microprocessor and random access memory (RAM) and that does some rudimentary processing without intervention from the host computer. Generally, a smart terminal can limit keyboard input to particular fields of the display and can perform some input validation (such as restricting input to numbers).

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