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agnar
1 posts
#15652 Memory cells/cyclic circuits
2 months, 3 weeks ago Edited by agnar on June 29, 2018, 9:14 a.m.

After watching the first two streams on DSL and circuit simulation, I've got a few questions that are related:

  • What are the plans for memory cells? Are they going to be abstracted into a type of Node or are they going to be built out of Nodes that are currently available?
  • Are cycles going to be simulated, or are we sticking to circuits without cycles?
  • Maykeye
    19 posts
    #15668 Memory cells/cyclic circuits
    2 months, 3 weeks ago

    Generally it would be nice to have plans.

    At least similar to

    https://github.com/pervognsen/bit...ob/master/notes/ion_motivation.md

    or even better - precise formal specification of the language . "Run and pray it works as you think it works " seems counterintuitive when it comes to hardware
    pervognsen
    Per Vognsen
    49 posts / 1 project
    #15686 Memory cells/cyclic circuits
    2 months, 2 weeks ago

    Those first few streams weren't intended to be anything other than Python/DSL warm-up. I tried to make that clear, but I'll try to emphasize that more.

    To answer your questions:

    Registers and memories in general will be abstracted into black box modules with the appropriate multi-cycle behavior. It won't be like Verilog or VHDL which has imperative simulation semantics at its core.

    It depends on what you mean by cycles. To build a state machine you need the next state to depend on the current state, but there isn't a true combinational loop because the apparent cycle is broken by flips flops or other memory elements. Combinational loops corresponding to logic equations like x = ~~~x (a ring oscillator) will be expressible in the circuit language (although not the toy subset that was demonstrated in the first two streams) but won't be simulated (it requires event-driven simulation) and we won't be needing anything like that for synthesis anyway.

    For the next couple of streams expect to still see some bottom-up exploration before I cover the longer-term plans.