Re: Forth CPUs with NO Interrupts

From	rickman <gnuarm@gmail.com>
Newsgroups	comp.lang.forth
Subject	Re: Forth CPUs with NO Interrupts
Date	2015-09-04 11:47 -0400
Organization	A noiseless patient Spider
Message-ID	<msceai$irl$1@dont-email.me> (permalink)
References	(16 earlier) <45f7f642-c80b-408d-8441-d90654639595@googlegroups.com> <ms9u6c$v8d$1@dont-email.me> <08d13917-fdbf-42c1-92be-4ee86e7893e3@googlegroups.com> <msamg3$2vm$1@dont-email.me> <fa53ca3d-cd54-4ef0-a2cb-81966104b201@googlegroups.com>

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On 9/4/2015 12:13 AM, Mux wrote:
>> 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.
>>
> Correct. One LE per bit per register. The EPF10k10 has 576 LE's and
> with both the data- and return stack being 8 deep (256LE's) and the
> remaining logic coming in at around ~100 LE's that leaves ample space
> for other things. The 10k10 only has 6144 bits of memory that I need
> for line-buffers and palettes. So yeah, it's a trade-off.
>
>> 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.
>
> Yup. The instructions are 4-bit each, which means I can fetch 4 of
> them at once. A '0=' instruction is used to for checking for zero
> (obviously) and consists of nothing more than at 16-way OR rather
> than a compare. no overflow or carry. Registered performance hovers
> somewhere around 200mhz with a tpd hovering around ~125mhz.

You lost me there.  What do you mean tpd?  Are you talking about the 
useful I/O rate?

> Nice
> thing is that it also has a single interrupt (like I stated earlier)
> source as well as a pre-fetch for the next 4-instructions from
> memory, based on some of the work from Eric La-Forest.

Is your memory external?  I've never gone that route since my uses for 
internal CPUs are always 100% internal.  I typically don't have room on 
the board for an external memory or the design is a retrofit where there 
was none in the first place.  Prefetching doesn't speed up a CPU running 
from internal memory since the block RAM is nearly as fast as a register.

BTW, what are your 4 bit instructions?  I've never been able to convince 
myself such a small instruction is the way to go.  Just as stack ISAs 
generate a fair percentage of code to thrash the stack, small 
instructions exacerbate this with the very few instructions possible. 
I'm wondering if VLIW isn't the way to go for stack machines.  But then 
the tools get more complex to optimize the parallelism or the user has 
to figure it all out themselves.

> On a somewhat different note,I don't particularly care for the
> hostilities in this- and other threads, or any on CLF. Not singling
> out anyone in particular but the bitch-fests that I've seen on this
> group far outweigh the actual useful posts where people actually try
> to help one-another.
>
> Just an observation...

I hope you aren't referring to my posts.  I try to avoid confrontation, 
but know I push Hugh's buttons sometimes.  I also get into "discussions" 
with Bernd sometimes that are less than productive.  I was surprised 
that a recent interaction with Hugh started to go in a semi-useful 
direction for a moment.  If I am crossing lines I would like for someone 
to tell me, but I expect it is hard to know where the line is in this 
group.  At least it isn't s.e.d where anything goes, including 
references to Nazis, lol.

-- 

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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