APPLYING THE UCSD UNIT CONCEPT.

The concept of UNIT is a UCSD process by which procedures can be collected for use as if they were a fundamental part of Pascal. Unlike INCLUDE files, UNIT's are previously compiled and tested, they need only to be linked to user programs. Unlike SEGMENT PROCEDUREs (overlays), they may define global CONSTants, TYPES, or VARiables and may contain any number of individually referenced PROCEDURES or FUNCTIONS. When a UNIT is compiled, the INTERFACE part is copied in TEXT format and the IMPLEMENTATION part is converted to object code. Later, when a program is compiled, the INTERFACE part is referenced. The definitions listed in the UNIT are then included in the outer block of the program. After a successful compilation, the linker copies the IMPLEMENTATION part along with the program code to a new. CODE file ready for use. Subsequent revisions to the UNIT will not affect the program unless it is recompiled or relinked.