III. Modes of Operation of the Compiler

There are two distinct modes of operation: ALGO and ALDAP.

ALGO is a compile-and-execute mode in which the two phases cannot be separated. The Algol program is translated into a machine language program in core memory, and execution of the program immediately and automatically follows. There is no assembly program phase.

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ALDAP makes use of the CODAP assembly program facilities. It is possible to compile procedures separately and reference them from an Algol program. The procedures may be written in Algol, CODAP or Fortran. This provision is made possible with the aid of the external declaration discussed in section V.

The ALGO mode provides significantly faster compilation than the ALDAP mode for most programs. The target programs produced in the two modes are essentially the same. In the ALGO mode, program checkout may be done at the Algol language level. In the ALDAP mode, checkout may also be done at the machine and assembly language levels, and modifications may be made at these levels.