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Technical pages
The FORTH kernel

The FORTH kernel equipping this system is based on the standard FORTH-79 with the following differences:

  • The data stack is size 32 bits size ( long word) instead of 16 bits (word). This allows to exploi all the resources of the microprocessor MC68030 (68000 for the mini system). On the other hand, it is always possible to manipulate words of 16 bits or bytes (8 bits). During a reading information of this width, all the most significant bits take the value of the 15-th bit for a word or of the 7-th bit for a byte. With this sign extension, all the arithmetic operations are valid from a word or from a byte.
  • The notion of vocabulary is no administered. It allows normally to optimize the durations of interpretation / compilation by minimizing the number of comparisons during the search for an instruction. My interpreter / compiler administers a table of indirection allowing the in order alphabetical classification of all the instructions what allows to have a maximum number of comparisons equal to the logarithm in base 2 of the total number of instructions: for 1000 instructions, the interpreter / compiler will have as well as 10 comparisons to be made at most to find an instruction either to decide tha it does not exist.

Instructions are presented in the following way:

  • Entry parameters taken in the data stack are in green color (an absence of parameter is indicated by the character "-"),
  • The instruction name is in red color,
  • The exit parameters placed in the data stack are in blue color (an absence of parameter is indicated by the character "-"),
  • The instruction description is in black color and in italic.

All the parameters are 32 bits numbers. When several parameters are indicated, they are separated with a comma. Parameter most to the left is the first deposited in the stack and that it more to the right constitutes the top of the stack.

All the instructions of the FORTH core are displayed in this page.

All the instructions of the FORTH mini system are displayed in this page.