Expand description
The Epson RTC-4513 real-time clock — the second ASIC on the one commercial cart that pairs it with SPC7110 (Far East of Eden Zero / Tengai Makyou Zero).
Clean-room port of ares’ EpsonRTC (ISC, sfc/coprocessor/epsonrtc/): a 3-register ($4840
chip-select, $4841 data, $4842 ready-status) handshake over a 16-nibble register file (the
clock fields + IRQ/mode bits). ares ticks a real wall-clock time into the register file
(EpsonRTC::synchronize); this port instead seeds a fixed epoch and never advances it other
than via explicit register writes — real wall-clock time would break this project’s
determinism contract (same seed + ROM + input ⇒ bit-identical output, docs/adr), and no game
logic here depends on the clock’s absolute value, only on the read/write handshake completing.
This project’s host-synced coprocessors (Super FX/CX4/the NEC DSP family) complete a triggered
operation instantly rather than modeling ares’ wait-cycle countdown (Thread::step); the RTC
follows the same convention — every write/read leaves ready set immediately, so a game’s
poll-for-ready loop always succeeds on its very next check.
Structs§
- Epson
Rtc - The Epson RTC-4513 register file + handshake state.