Instruction-level emulator for Atto-8 microcomputer
The emulator loads a memory image file from argv[1] which must be exactly 0x100 bytes in size. Emulation is performed at the instruction level; that is, the emulator is built to test binaries, not to mirror the hardware. The emulator adheres to the Atto-8 microcomputer specification as defined in /spec/microcomputer.md.
Emulation will exit upon receiving SIGINT (Ctrl+C) or SIGTERM (kill). The emulator will enter debug mode upon encountering an illegal opcode.
The emulator sends most characters received from stdin to the Atto-8’s standard input and sends most characters received from the Atto-8’s standard output to stdout. The following characters are exceptions:
Del— Clear standard output.Tab— Toggle displaying machine state.Escape— Forcefully enter debug mode.
The Atto-8 microcomputer is equipped with a pair of D-pad controllers. The emulator reads input from stdin and maps it to the following controller buttons:
ArrowUp— Primary UpArrowDown— Primary DownArrowLeft— Primary LeftArrowRight— Primary RightPageUp— Secondary UpPageDown— Secondary DownHome— Secondary LeftEnd— Secondary Right
Unofficial opcode 0xBB is treated as a debug request. Debug mode can be entered forcefully by hitting Escape during emulation.
In debug mode, the emulator will print the current machine state and wait for a command to be sent to stdin. The following commands are supported:
Del— Clear standard output.Tab— Step one instruction.Escape— Continue emulation.