3 ms·

PIC 16F84 is also non-von neumann

• Sanddancer 13y ago
  Most microcontrollers are. Makes certain bits of design and coding a lot easier. The AVR, some ARM Cortex Ms, etc, share that.
  • duskwuff 13y ago
    As far as I know, all ARM CPUs are Von Neumann, in that they use the same memory space for instructions and data. The program is often stored in read-only memory (flash), but it's in the same space as SRAM and hardware registers. AVR, on the other hand, is a Harvard architecture, as the program does not exist in the same address space as data. It is possible to read from program memory, but only using special-purpose instructions. I believe the same goes for PIC, but I'm not as familiar with it. The description of this machine isn't quite detailed enough for me to say for sure, but I think it may be a Von Neumann architecture, if only because I don't see any labeled instruction memory. I may be misunderstanding how it's supposed to work, though.
    • Sanddancer 13y ago
      The Cortex-M3 and M4 ARMs are Mostly Harvard; just pored through the datasheets to make sure. The first half a gig of address space has a separate bus for code and data, and then has yet another bus for all the memory space above that. They're weird little chips.
      • duskwuff 13y ago
        It's all the same data and the same address space, though. The first half-gig or so of memory is all flash ROM, so the separate bus just gives the CPU an extra load per cycle (so it can load data from ROM without a wait state). This doesn't make it a Harvard architecture, it just makes it faster.