Nintendo Entertainment System · build log

Save states that move between boards

The NES now runs on a second board, the Sipeed Tang Console 138K, with its memory in block RAM, and every test gives the same CRCs as on the Tang Nano 20K: nestest 0xebba51ce, and all 42 PPU test ROMs with MesenCE’s frames.

A save-state controller stops the system at a frame boundary and copies the CPU, the PPU and every RAM, 20,920 bytes, out through the test shell and back. Saved partway through a test, reset, restored and finished, a run ends with the same frame, line CRCs, bus trace and cycle count as an uninterrupted one. A state saved halfway on either board also finishes on the other with MesenCE’s frames, for nmi_sync, sprite_overflow-3 and ppu_vbl_nmi-10.