In 2020, Apple announced the transition of Mac processors from Intel to its own Apple Silicon, and several Mac devices are already equipped with M-series chips. But during the transition to allow applications to run on the M-series chips, Apple introduced an analog solution called “Rosetta 2”.
Australian security researcher Dougall Johnson recently discovered an undisclosed extension to Rosetta 2 that simplifies the process of storing parity and tuning flags within the application after digging into it. He says this could make simulations more accurate and faster.
What’s even more surprising about this extension is that it originated with the second processor released by Intel, the 8080 processor released by Intel in 1974.
This ancient 8-bit microprocessor handled these adjustments and parity storage very specifically and this feature is always present in today’s Intel processors. Even the latest Core i9-13900K is directly related to the processor that powered some computers nearly 50 years ago.
Bits 26 and 27 in ARM’s flag register are dedicated to this process, except that these two bits are only assigned to this action when Rosetta 2 is active.
Rosetta 2 will not activate by default unless it detects that a program is made with an Intel-based Mac, reassigning these two bits and allowing Rosetta 2 to work at its usual fast pace.