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
Turbo Pascal supported remote debugging via an RS232 communication cable. Over the years, Borland enhanced not only the IDE, but also extended the programming language. A development system based on ISO standard Pascal requires implementation-specific extensions for the development of real-world applications on the platforms they target. Standard Pascal is designed to be platform-independent, so prescribes no low-level access to hardware- or operating system-dependent facilities. Standard Pascal also does not prescribe how a large program should be split into separate compilation units. From version 4, Turbo Pascal adopted the concept of "units" from UCSD Pascal. Units were used as external function libraries,