I worked some of the follow on projects to the 777 that involved the next generation 737. A lot of people may not realize this, but much of the software and avionics that goes into Boeing aircraft is designed, built, and manufactured by other smaller third parties. The amount of work that goes into those embedded systems is truly impressive. Additionally, the rigor with which it is built is exemplary. Software standards for commercial aviation are extremely strict, disallowing the use of dynamic memory allocation, pointer math, and other typical low-level language "features" or "shortcuts". There are also strict code coverage test requirements, demanding that primary partitions of the flight avionics have their code tested in what is known as MCDC [1] Additionally, I/O code that uses low level data buses must be tested for bit independence. The process is extremely rigorous.

[1] https://en.wikipedia.org/wiki/Modified_condition/decision_co...