Re: Forth CPUs with NO Interrupts

From	rickman <gnuarm@gmail.com>
Newsgroups	comp.lang.forth
Subject	Re: Forth CPUs with NO Interrupts
Date	2015-09-03 19:54 -0400
Organization	A noiseless patient Spider
Message-ID	<msamg3$2vm$1@dont-email.me> (permalink)
References	(14 earlier) <710fa208-7afe-4810-8121-9da26a0f3232@googlegroups.com> <ms84v8$vod$3@dont-email.me> <45f7f642-c80b-408d-8441-d90654639595@googlegroups.com> <ms9u6c$v8d$1@dont-email.me> <08d13917-fdbf-42c1-92be-4ee86e7893e3@googlegroups.com>

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On 9/3/2015 6:54 PM, Mux wrote:
>> Yes and very inefficient in terms of logic utilization.  A high price to
>> pay for performance which may or may not pan out.  I find the block RAMs
>> are not in any of the critical timing paths of any CPU I've designed.
>>
>> --
>>
>> Rick
>
> How is that inefficient if it's one LE per bit? As far as performance goes, it's well into the 200mhz performance range which is fast enough for me on a cheap FPGA. I'm not looking into spending $$$ to get FPGA's in the Ghz range. Anything that runs at about 50-100mhz will do nicely for me..

Not one LE per bit, one LE per bit per register.  If you are working in 
a part where you have lots of LEs to use, fine.  My CPU design uses 600 
LUTs total plus 1 block RAM for both stacks (not 1 each) and whatever 
data/program memory you need to use.  Using 256 LUTs for the stack 
registers seems like a poor tradeoff to me, but it all depends on what 
you have lots of.

Does your entire CPU run at 200 MHz?  The decode must be very simple.  I 
take it you have a zero compare instruction rather than flags?  What 
about detecting carry or overflow?  Those are the speed critical paths 
in my design.  In a 15 year old Altera FPGA it ran at 50 some MHz.  I 
only ever had one application for it though, so I spent a little time 
looking at improvements, but never worked with it further.

-- 

Rick

Thread

Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-08-26 00:53 -0400
  Re: Forth CPUs with NO Interrupts anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-26 08:51 +0000
    Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-08-26 08:50 -0400
    Re: Forth CPUs with NO Interrupts "Elizabeth D. Rather" <erather@forth.com> - 2015-08-26 07:23 -1000
  Re: Forth CPUs with NO Interrupts Mark Wills <markwills1970@gmail.com> - 2015-08-26 04:33 -0700
    Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-08-26 08:46 -0400
    Re: Forth CPUs with NO Interrupts mhx@iae.nl - 2015-08-26 11:17 -0700
    Re: Forth CPUs with NO Interrupts hughaguilar96@gmail.com - 2015-08-26 12:50 -0700
      Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-08-26 18:28 -0400
    Re: Forth CPUs with NO Interrupts hughaguilar96@gmail.com - 2015-08-27 23:44 -0700
      Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-08-28 18:28 -0700
  Re: Forth CPUs with NO Interrupts Walter Banks <walter@bytecraft.com> - 2015-08-26 11:41 -0400
  Re: Forth CPUs with NO Interrupts Syd Rumpo <usenet@nononono.co.uk> - 2015-08-26 17:12 +0100
    Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-08-26 09:48 -0700
    Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-08-26 18:39 -0400
  Re: Forth CPUs with NO Interrupts "Ala'a Alawi" <amalawi@gmail.com> - 2015-08-27 08:37 -0700
  Re: Forth CPUs with NO Interrupts pbjtech@gmail.com - 2015-08-30 19:01 -0700
    Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-08-30 22:45 -0400
      Re: Forth CPUs with NO Interrupts Reinhardt Behm <rbehm@hushmail.com> - 2015-08-31 11:09 +0800
    Re: Forth CPUs with NO Interrupts hughaguilar96@gmail.com - 2015-08-30 20:06 -0700
      Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-08-30 23:20 -0400
        Re: Forth CPUs with NO Interrupts hughaguilar96@gmail.com - 2015-09-02 14:14 -0700
          Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-02 18:02 -0400
      Re: Forth CPUs with NO Interrupts Bob <bob@none.com> - 2015-08-31 20:49 -0400
        Re: Forth CPUs with NO Interrupts Mark Wills <markwills1970@gmail.com> - 2015-09-01 01:39 -0700
          Re: Forth CPUs with NO Interrupts dunno <dunno@dunno.dunno> - 2015-09-01 17:58 +0000
          Re: Forth CPUs with NO Interrupts Bob <bob@none.com> - 2015-09-01 18:48 -0400
            Re: Forth CPUs with NO Interrupts hughaguilar96@gmail.com - 2015-09-01 16:32 -0700
            Re: Forth CPUs with NO Interrupts Bernd Paysan <bernd.paysan@gmx.de> - 2015-09-02 01:38 +0200
              Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-01 22:09 -0400
                Re: Forth CPUs with NO Interrupts Bernd Paysan <bernd.paysan@gmx.de> - 2015-09-02 14:12 +0200
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-02 12:40 -0400
                Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-09-02 10:40 -0700
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-02 16:57 -0400
                Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-09-02 14:55 -0700
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-02 18:11 -0400
                Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-09-02 16:20 -0700
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-02 20:42 -0400
                Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-09-02 22:34 -0700
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-03 12:59 -0400
                Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-09-03 15:54 -0700
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-03 19:54 -0400
                Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-09-03 21:13 -0700
                Re: Forth CPUs with NO Interrupts Jan Coombs <Jan-54 <jenfhaomndgfwutc@murmic.plus.com>> - 2015-09-04 09:48 +0100
                Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-09-04 08:49 -0700
                Re: Forth CPUs with NO Interrupts hughaguilar96@gmail.com - 2015-09-04 11:15 -0700
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-04 14:32 -0400
                Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-09-04 11:36 -0700
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-04 17:46 -0400
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-04 11:47 -0400
                Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-09-04 09:20 -0700
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-04 12:52 -0400
                Re: Forth CPUs with NO Interrupts Mux <Yvo.Zoer@gmail.com> - 2015-09-04 10:20 -0700
                Re: Forth CPUs with NO Interrupts Bernd Paysan <bernd.paysan@gmx.de> - 2015-09-02 23:35 +0200
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-02 18:09 -0400
                Re: Forth CPUs with NO Interrupts Bernd Paysan <bernd.paysan@gmx.de> - 2015-09-03 02:07 +0200
                Re: Forth CPUs with NO Interrupts rickman <gnuarm@gmail.com> - 2015-09-02 20:49 -0400
                Re: Forth CPUs with NO Interrupts Bernd Paysan <bernd.paysan@gmx.de> - 2015-09-03 14:30 +0200
    Re: Forth CPUs with NO Interrupts hughaguilar96@gmail.com - 2015-09-02 14:23 -0700

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