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Emulation Mode Flag: Difference between revisions
From SnesLab
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The flag is set when a [[RESET]] interrupt is fired. In other words, the CPU always starts in emulation mode at boot and after a reset. | The flag is set when a [[RESET]] interrupt is fired. In other words, the CPU always starts in emulation mode at boot and after a reset. | ||
The 65c816 does not attempt to emulate the illegal 6502 opcodes. | |||
=== Reference === | === Reference === | ||
Revision as of 11:33, 17 July 2024
The Emulation Mode Flag (E) controls whether the 65c816 is behaving like a 6502.
When clear, the MPU is in 65c816 native mode.
When set, the MPU is in 6502 emulation mode.
This flag cannot be modified directly and is normally hidden from the programmer. To modify it, use the XCE instruction to swap its value with the carry flag's value.
The flag is set when a RESET interrupt is fired. In other words, the CPU always starts in emulation mode at boot and after a reset.
The 65c816 does not attempt to emulate the illegal 6502 opcodes.
Reference
- Figure 17.3, Eyes & Lichty page 377, https://archive.org/details/0893037893ProgrammingThe65816/page/n403