[scordova]

A guided tour of an ancestor and its hardware







The virtual CPU, which is the default "body" or "hardware" of the organisms, contains the following set of components.

A memory that consists of a sequence of instructions, each associated with a set of flags to denote if the instruction has been executed, copied, mutated, etc.

An instruction pointer (IP) that indicates the next site in the memory to be executed.

Three registers that can be used by the organism to hold data currently being manipulated. These are often operated upon by the various instructions, and can contain arbitrary 32-bit integers.

Two stacks that are used for storage. The organism can theoretical store an arbitrary amount of data in the stacks, but for practical purposes we currently limit the maximum stack depth to ten.

An input buffer and an output buffer that the organism uses to receive information, and return the processed results.

A Read-Head, a Write-Head, and a Flow-Head which are used to specify positions in the CPU's memory. A copy command reads from the Read-Head and writes to the Write-Head. Jump-type statements move the IP to the Flow-Head.



One major concept that differentiates this virtual assembly language from its real-world counterparts is in the additional uses of nop instructions (no-operation commands). These have no direct effect on the virtual CPU when executed, but often modify the effect of any instruction that precedes them. In a sense, you can think of them as purely regulatory genes. The default instruction set has three such nop instructions: nop-A, nop-B, and nop-C.