A deep dive into the PC Engine (TurboGrafx-16) CPU as part of an ongoing emulator project. The HuC6280 is a heavily modified 65C02 (8-bit, not 16-bit despite the name) running at up to 7.16 MHz — twice the SNES CPU speed with minimal memory latency. The post covers the built-in MMU that expands the address space from 16-bit to 21-bit via eight 8 KB memory page registers, unique block transfer instructions (TAI, TDD, TIA, TII, TIN) that serve as a software DMA substitute, and other HuC6280-exclusive instructions like SET, BSR, TST, and the VDC-specific ST0/ST1/ST2. Comparisons are drawn to the NES 6502, SNES 65C816, and Genesis 68000 CPUs throughout.
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