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The Bitscope PIC is a programmable virtual machine.
- RISC style instruction set of 42 single byte instructions.
- Instructions operate on a set of 46 single byte registers.
- Execution is "live" via the serial port.
- No programs are stored in Bitscope memory.
- Programs called scripts define the operation of Bitscope.
- All instruction execution is atomic which is very important.
A virtual machine design has a number of advantages.
-
Efficiency: each instruction may be highly optimized for performance.
A general interpreter like BASIC can do anything - but in a very inefficient
way. A virtual machine instruction is compact like assembly code, but may
perform an extremely complex task.
-
Modularity: once a register set and basic command set are devised,
extensions may be made by adding new instructions to enhance the machine.
The original instructions remain the same.
-
Portability: changes to the physical machine (ie PIC)
have little impact on the virtual machine design and the
software that runs on the virtual machine.
The virtual machine looks like a simple RISC CPU with a set of
byte code instructions operating on a set of byte wide
registers. Virtual machine programs (scripts) are stored in the
host but executed in the virtual machine byte-by-byte as they
are received on the serial port.
Because they live in host memory, scripts are not limited to
the memory in Bitscope itself. The virtual machine design means
you do not need to know PIC programming to program Bitscope.
Consequently it is very easy to program Bitscope.
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