I'm going to just call interrupts, syscalls, page faults, privilege errors etc. exceptions from now on to save typing. Since the current design of exceptions has a few flaws, we need a new design. I'm not keen on redesigning the existing hardware I've made if possible, so that means no …

My first attempt at implementing interrupt, syscall and exception handling in MUPS/16 currently has 4 types of traps:

• interrupts (currently 4, with equal priority)
• page faults
• syscalls
• privilege errors

Syscalls are handled slightly differently as they are completely synchronous, and so can be treated just as another instruction (R-type …