As the programmer, I don't really care what the h/w does; if I specify u8 and every operation produces results 'as if' the type were 8 actual unsigned bits, eg, when using an underlying u32 type -- great. From 'my model' -- it's still a u8.
But there must be no conceptual 'leaking' (behaviors that I experience using e.g. uint_fast8_t that are in any way different from behaviors I experience when using u8 ).
I don't especially care how the HW works; because my 'virtual machine' is C. (yes, yes, I know Reality intrudes, and sometimes you need to get closer to the machine. But, isn't this because of 'leaking' between 'virtual machine' and 'actual machine' that I mention above?)
But there must be no conceptual 'leaking' (behaviors that I experience using e.g. uint_fast8_t that are in any way different from behaviors I experience when using u8 ).
I don't especially care how the HW works; because my 'virtual machine' is C. (yes, yes, I know Reality intrudes, and sometimes you need to get closer to the machine. But, isn't this because of 'leaking' between 'virtual machine' and 'actual machine' that I mention above?)