Pressure measurement because atmospheric pressure is always changing and the reference in this case is fixed at 1 bar. To produce an absolute pressure sensor, the manufacturer seals a high vacuum behind the sensing diaphragm. If the process-pressure connection of an absolute-pressure transmitter is open to the air, it will read the actual barometric pressure. The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N·m or kg·m·s). This special name for the unit was added in 1971; before that, pressure in SI was expressed in units such as N·m. When indicated, the zero reference is
Free Pascal one dialect can be used per program. It follows a "write once, compile anywhere" philosophy, and is available for many CPU architectures and operating systems (see Targets). It supports inline assembly language and includes an internal assembler capable of parsing several dialects such as AT&T and Intel style. Separate projects exist to facilitate developing cross-platform graphical user interface (GUI) applications, the most prominent one being the Lazarus integrated development environment (IDE). Initially, Free Pascal adopted the "de facto" standard dialect of Pascal programmers, Borland Pascal but later on adopted Delphi. From version 2.0 on, Delphi compatibility has been continuously implemented