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Prop II question. Undoubtedly covered before, but... — Parallax Forums

Prop II question. Undoubtedly covered before, but...

MarkSMarkS Posts: 342
edited 2008-01-08 01:54 in Propeller 1
Would it be possible to design the chip so that the programmer could optionally designate an external address (I2C, maybe?) for the code (via a program counter?), so that the Prop does not load it into memory, but runs it directly from an external EEPROM? It would be nice to not have a program size limitation, even if it meant a slow down in operating speed. It would be nice to designate that Cog 0 run the code from address x to y and Cog 1 from y to z, etc.

Comments

  • RinksCustomsRinksCustoms Posts: 531
    edited 2008-01-08 01:24
    Sounds complex, read it 3 times and still not 100% sure what your getting at. One thing i've noticed being an autobody tech for 15yrs working on everything from a '63 MG to 12 cylinder Mercedes, the more complex it is or the more gadget's it has just means there's more to go wrong later.

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  • deSilvadeSilva Posts: 2,967
    edited 2008-01-08 01:34
    An 32 bit instruction is fetched each 50 ns inside the COG. This comes to a serial bandwith of 640 MHz. This is not really I2C

    It might look better with SPIN: A SPIN bytecode it fetched around each µs, so we need just 8 MHz That could be accomplished with a kind of SPI.

    As the PROP II will run 4 times faster, we have to consider this: it will become 3,2GHz then for COG instructions and 32MHz for SPIN to make it competative...
  • hippyhippy Posts: 1,981
    edited 2008-01-08 01:54
    Sounds more like a job for a LMM Virtual Machine or a home-grown Spin Interpreter rather than messing with the complexities of the hardware chip itself.

    Once you boot-up to a minimal Spin program ( which can launch whatever it needs to ) you have far more flexibility to do whatever you want than could be provided in hardware. You could choose to run from I2C eeprom, SD Card, HDD, even download code from the internet or server to execute. And of course you can change the code as things evolve.

    What you suggest could be done in software with the Propeller as it is now with a little bit of work.
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