Re: GA144 article

From	Paul Rubin <no.email@nospam.invalid>
Newsgroups	comp.lang.forth
Subject	Re: GA144 article
References	(13 earlier) <677bc860-fa98-4ca8-a557-7aa70c11876f@googlegroups.com> <7xk3xhj2gw.fsf@ruckus.brouhaha.com> <19981049-2688-4f99-83cc-6f6b1ac5221d@googlegroups.com> <7xk3xhou8t.fsf@ruckus.brouhaha.com> <c999b0ef-d293-4ebd-9a2d-e76eb0cb73cb@googlegroups.com>
Date	2012-08-02 16:38 -0700
Message-ID	<7xy5lw985e.fsf@ruckus.brouhaha.com> (permalink)
Organization	Nightsong/Fort GNOX

Show all headers | View raw

rickman <gnuarm@gmail.com> writes:
> I saw how you got the 3.5 number, but what is it's purpose?  There are
> four instructions in a word.  Why call it 3.5 instructions?  

There's only 4 instructions per word if you can actually use all 4
slots.  The 4th slot is useless a lot of the time because there are only
3 bits in it, so only 8 of the 32 possible opcodes can go into it, so
you end up having to put a no-op there.  The other slots are also often
not usable for instructions or cause an extra fetch, because you need to
bring in a literal.  4 instructions is the maximum, and it's achievable
only some of the time, so the average is less than 4.  I picked 3.6 as a
reasonable-looking estimate.  If you've got a better one, go ahead and
post it.

> Why are you adding 3500 to the other numbers you posted?  I don't see
> the meaning of this calculation.

3500 for the port delay per your post, plus some unknown (guesstimated
above) amount for instruction fetch, averaged out across instructions.
You wrote:

> GA144 data book page 19...
> TIOREG IO register read/write opcode time @+ @b @ !+ !b ! 3250 3500 4100 pS
> The last three numbers are Min Typ and Max timings

3500 according to you is typical, so I used that.  Again, if you don't
like my estimate, feel free to post your own.  I don't think there is
enough info to do a really reliable calculation, but the available info
seems like a reasonable starting point.  Otherwise we have to assume the
worst possible case, which is intolerable delays in getting stuff around
between nodes.

Back to comp.lang.forth | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Re: GA144 article Daniel Kalny <dkalny@seznam.cz> - 2012-07-24 02:37 -0700
  Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-07-24 03:12 -0700
    Re: GA144 article stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-24 10:36 +0000
      Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-07-24 10:28 -0700
        Re: GA144 article Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-24 22:12 +0000
    Re: GA144 article rickman <gnuarm@gmail.com> - 2012-07-24 14:49 -0700
      Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-07-26 13:25 -0700
        Re: GA144 article rickman <gnuarm@gmail.com> - 2012-07-27 13:17 -0700
          Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-07-27 14:31 -0700
            Re: GA144 article rickman <gnuarm@gmail.com> - 2012-07-27 22:02 -0700
              Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-07-28 23:03 -0700
                Re: GA144 article marko <marko@marko.marko> - 2012-07-30 09:12 +1000
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-07-31 01:09 -0700
                Re: GA144 article marko <marko@marko.marko> - 2012-08-01 00:19 +1000
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-07-31 09:59 -0700
                Re: GA144 article marko <marko@marko.marko> - 2012-08-01 10:13 +1000
                Re: GA144 article Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-01 00:59 +0200
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-07-31 16:54 -0700
                Re: GA144 article Luca Saiu <positron@gnu.org> - 2012-08-04 10:46 +0200
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-08-05 11:04 -0700
                Re: GA144 article Luca Saiu <positron@gnu.org> - 2012-08-06 02:02 +0200
                Re: GA144 article Mark Wills <markrobertwills@yahoo.co.uk> - 2012-08-06 02:16 -0700
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-07-30 08:23 -0700
                Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-07-30 21:33 -0700
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-07-31 01:51 -0700
                Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-07-31 11:48 -0700
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-07-31 14:54 -0700
                Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-07-31 16:09 -0700
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-08-01 12:57 -0700
                Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-08-01 14:16 -0700
                Re: GA144 article vandys@vsta.org - 2012-08-01 22:32 +0000
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-08-01 16:03 -0700
                Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-08-01 16:13 -0700
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-08-01 16:10 -0700
                Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-08-01 22:18 -0700
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-08-02 11:47 -0700
                Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-08-02 14:32 -0700
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-08-02 16:01 -0700
                Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-08-02 16:38 -0700
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-08-03 08:40 -0700
                Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-08-03 09:19 -0700
                Re: GA144 article rickman <gnuarm@gmail.com> - 2012-08-03 11:15 -0700
                Re: GA144 article Paul Rubin <no.email@nospam.invalid> - 2012-08-05 15:50 -0700
                Re: GA144 article Mark Wills <markrobertwills@yahoo.co.uk> - 2012-08-06 02:21 -0700

csiph-web