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compiler and interpreter: A compact portable system for MSDOS and CP/M permission is granted free for personal use
An economic use of resources is achieved by compiling the Algol source into code for a virtual machine, which is implemented in assembly language. The complete system has two compilers and two virtual machines, an integer only subset and the full version. Both compilers are written in the Algol subset, the subset compiler is self compiling. In order to make it as small and fast as possible, the subset virtual machine interpreter has very little error checking. Devoid of floating point, nested procedure declarations, stack checking and a few other things, the subset compiler is ultra lean. The full compiler at 17K bytes is only just larger than the full virtual machine interpreter. The output of the subset compiler is code for the subset virtual machine, but expressed in assembly language. The compilers are one pass and very fast. They use the method of recursive descent.
In education, the Algol-60 system can be used as an example of a compiler and how the best use was made of very limited resources. It is a real world compiler which was a commercial success, now available in source code form.
The download includes the full user manual, which contains a description of the generated code and details of the stack layout.
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