The ScottE is an 8bit processor based on Scott's CPU in his book "But How Do It Know". It differers from the original in these points:
- Use of microcode instead of fixed logic as Control Unit.
- Completely reworked microarchitecture that removes the bus bottleneck of the original.
- Support for subtraction and hence different ALU flags.
- Extended address space with memory-mapped IO.
- Stack support with the stack pointer register.
- Modified, removed and new instructions.
Thus it is neither binary compatible nor semantically compatible with the original CPU.
This processor is designed with the Logisim software. Read the documentation on the website or watch videos on Youtube for information concerning the usage of that tool.