I guess this is more of an embedded thing, but ... <http://lwn.net/Articles/647636/> “He then asked what constitutes the minimal system that can run Linux. All that is really needed, he said, is a flat, 32-bit memory address space, a CPU with registers to hold instructions, some I/O and storage (from which the kernel and initramfs can be loaded), and a timer for interrupts. That plus GCC is sufficient to get Linux running—although it may not be fast, depending on the specifics. One does not even need a cache, floating-point unit, SMP, or a memory-management unit (MMU).” “The other main advantage of the J2 project is that the work for implementing SuperH support is already done in the kernel, GCC, GDB, strace, and most other system components.” “The project has thus "inherited" an excellent ISA, and has even been in contact with many of the former Hitachi employees that worked on SuperH.” “...there are many ASIC vendors who are happy to produce low-cost chips on their older equipment because the cost of retooling a plant is exorbitant. A 180nm implementation of the J2 design, he said, costs around three cents per chip, with no royalties required. "That's disposable computing at the 'free toy inside' level."” “At the end of the talk, an audience member voiced concern that SuperH was old enough that support for it is unmaintained in a lot of projects. He suggested that the J2 team might need to act quickly to stop its removal. Landley noted that, indeed, the latest buildroot release did remove SuperH support, "but we're trying to get them to put it back now."”