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The Biota Computer

by Ward Cunningham github

Biota is a simulation of an imaginary computer with some unusual properties. Its memory is addressed by points held in registers that can be incremented in any of eight possible directions. Programs are interpreted by following strings of non-blank instructions as they wind through memory. Loops and branches appear as exactly that. The program counter turns to avoid blanks and failing instructions. smalltalk, javascript

Installation

  1. Launch Glamorous Toolkit and open a Playground.
  2. Paste the following lines into the playground and run them (Evalute):
Metacello new
    baseline: 'Biota';
    repository: 'github://RalfBarkow/biota:main/src';
    load.

And then load the documentation in Glamorous Toolkit:

BaselineOfBiota loadLepiter

Classes

Biota -- A two dimensional space, addressed by points, which stores the characters that are biota programs and data. Class methods define the size of the space and a single character, called empty, that marks unused cells.

DisplayBiota -- A kind of biota that echos it's modifications the computer display.

BiotaIndex -- A kind of point that includes a direction and responds to turtle style protocol (go, turn).

BiotaEngine -- A processor that can interpret programs stored in a biota. Includes a loader and debugger. A class method constructs an instruction dispatch table from a method dictionary.

The loader expects data in odd numbered columns and control characters in the others. '$' marks the initial program counter; '#' the initial data pointer. (Use cut and paste to type these characters.)

The debugger will single step with each press of the space bar. Press and hold 'r' to run at high speed. 'q' will quit. (Collapse or frame all windows to the bottom inch of the display before running. Redraw screen when finished.)

TestEngine -- An experimental biota engine with twelve instructions. Class methods answer sample programs written for this engine.

The instructions 't' and 'u' turn right and left. 's' and 'b' step forward and backward. 'd' and 'r' duplicate data, 'r' more aggressively. 'c' clears data to blank. 'f' faces the data pointer at the nearest data while 'h' alignes it with the program counter. 'g' combines 'f' and 's'. 'a' and 'q' are obsolete and should be avoided.