Not all of these imply any sort of expertise, only that I did produce something in each, however small or badly written. (Contrast the 9900, for which I wrote exactly one subroutine, with the 34010, for which I wrote a complete low-level graphics library, defined a custom ABI for higher-level C code, and for which I ported the DIAB C compiler. [The magnificent and highly-retargetable DIAB compiler is still out there, now owned by Wind River, though they've almost certainly never heard of that 34010 cross-compiler I did.])