The CPU demos are small but complete computers. Program memory holds trytes, and the program counter normally begins at address 0 unless a program says otherwise.
Choose a CPU demo under Demo projects, such as the small inspectable computer or the larger-memory version. Then choose Program → Load example to fill memory without necessarily starting execution.
Select Program / data memory. Inspector shows memory rows with an address, a tryte, and a decoded instruction when the row contains an instruction. The highlighted or current program-counter address shows where the CPU is.
Memory can also contain ordinary data. A mnemonic in the list is therefore a decoding aid for instruction-shaped trytes, not a guarantee that every row is executable code.
Use Computer → Instruction step to run one whole instruction. After every step, inspect:
- the program counter (PC),
- the instruction register,
- register values,
- memory access and I/O.
Computer → Run computer is better once you know the program should keep running without stopping. Reset or load the example again when you want to start from the first instruction.
Open Program → Write program to write a short program in the editor. You can validate and load it into memory before execution starts. Use Import program and Export program to share a program with someone else.
The instruction format, mnemonics, and current opcode table are in ISA.md.
Continue to Tutorial 4 when a program does not behave as expected.