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Groups > comp.arch.embedded > #28223

Re: $0.03 microcontroller

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.arch.embedded
Subject Re: $0.03 microcontroller
Date 2018-10-14 14:32 +0200
Organization A noiseless patient Spider
Message-ID <ppvd11$v0t$1@dont-email.me> (permalink)
References (5 earlier) <db074a68-df45-4b56-8ae4-80ebc451eaeb@googlegroups.com> <ppsido$59m$1@dont-email.me> <7205434a-abd7-4b95-b4c7-d25d90cc6071@googlegroups.com> <tf04sdt3sapu3t7vgli6ofbr9okpa9793g@4ax.com> <817bef86-b326-4a00-bc29-21ba0fdec587@googlegroups.com>

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On 14/10/18 03:20, gnuarm.deletethisbit@gmail.com wrote:
> On Saturday, October 13, 2018 at 11:00:30 AM UTC-4,
> upsid...@downunder.com wrote:
>> On Sat, 13 Oct 2018 05:06:23 -0700 (PDT), 
>> gnuarm.deletethisbit@gmail.com wrote:
>> 
>>> On Saturday, October 13, 2018 at 6:46:20 AM UTC-4, David Brown
>>> wrote:
>>>> On 12/10/18 18:11, gnuarm.deletethisbit@gmail.com wrote:
>>>>> On Friday, October 12, 2018 at 2:50:53 AM UTC-4, Philipp
>>>>> Klaus Krause wrote:
>>>>>> Am 12.10.2018 um 01:08 schrieb Paul Rubin:
>>>>>>> upsidedown@downunder.com writes:
>>>>>>>> There is a lot of operations that will update memory
>>>>>>>> locations, so why would you need a lot of CPU
>>>>>>>> registers.
>>>>>>> 
>>>>>>> Being able to (say) add register to register saves
>>>>>>> traffic through the accumulator and therefore
>>>>>>> instructions.
>>>>>>> 
>>>>>>>> 1 KiB = 0.5 KiW is quite a lot, it is about 10-15 pages
>>>>>>>> of commented assembly program listing.
>>>>>>> 
>>>>>>> It would be nice to have a C compiler, and registers help
>>>>>>> with that.
>>>>>>> 
>>>>>> 
>>>>>> Looking at the instruction set, it should be possible to
>>>>>> make a backend for this in SDCC; the architecture looks
>>>>>> more C-friendly than the existing pic14 and pic16 backends.
>>>>>> But it surely isn't as nice as stm8 or z80. reentrant
>>>>>> functions will be inefficent: No registers, and no
>>>>>> sp-relative adressing mode. On would want to reserve a few
>>>>>> memory locations as pseudo-registers to help with that, but
>>>>>> that only goes so far.
>>>>> 
>>>>> CPUs like this (and others that aren't like this) should be 
>>>>> programmed  in Forth. It's a great tool for small MCUs and
>>>>> many times can be hosted on the target although not likely in
>>>>> this case. Still, you can bring enough functionality onto the
>>>>> MCU to allow direct downloads and many debugging features
>>>>> without an ICE.
>>>>> 
>>>>> Rick C.
>>>>> 
>>>> 
>>>> Forth is a good language for very small devices, but there are
>>>> details that can make a huge difference in how efficient it is.
>>>> To make Forth work well on a small chip you need a
>>>> Forth-specific instruction set to target the stack processing.
>>>> For example, adding two numbers in this chip is two
>>>> instructions - load accumulator from memory X, add accumulator
>>>> to memory Y.  In a Forth cpu, you'd have a single instruction
>>>> that does "pop two numbers, add them, push the result". That
>>>> gives a very efficient and compact instruction set.  But it is
>>>> hard to get the same results from a chip that doesn't have this
>>>> kind of stack-based instruction set.
>>> 
>>> Your point is what exactly?  You are comparing running forth on
>>> some other chip to running forth on this chip.  How is that
>>> useful?  There are many other chips that run very fast.  So?
>>> 
>>> I believe others have said the instruction set is memory oriented
>>> with no registers.
>> 
>> Depending how you look at it, you could claim that it has 64
>> registers and no RAM. It is a quite orthogonal single address
>> architecture. You can do practically all single operand
>> instructions (like inc/dec, shift/rotate etc.) either in the
>> accumulator but equally well in any of the 64 "registers". For two
>> operand instructions (such as add/sub, and/or etc,), either the
>> source or destination can be in the memory "register".
>> 
>> Both  Acc = Acc Op Memory or alternatively  Memory = Acc Op Memory
>> are valid.
>> 
>> Thus the accumulator is needed only for two operand instructions,
>> but not for single operand instructions.
> 
> How fast are instructions that access memory?  Most MCUs will perform
> register operations in a single cycle.  Even though RAM may be on
> chip, it typically is not as fast as registers because it is usually
> not multiported.  DSP chips are an exception with dual and even
> triple ported on chip RAM.

Single cycle, according to the manual.  Instructions involving 16-bit 
values are two cycle, the conditional branch instructions may be one or 
two cycles, and everything else is one cycle.

It is not so hard to make the RAM dual ported when there is only 64 
bytes of it.  Or perhaps the core is clocked on both falling and rising 
edges, so that the instructions are effectively 2/4 clocks rather than 1 
or two.  We can only guess.

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Thread

$0.03 microcontroller Clifford Heath <no.spam@please.net> - 2018-10-10 12:05 +1100
  Re: $0.03 microcontroller lasselangwadtchristensen@gmail.com - 2018-10-10 16:12 -0700
  Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-10 17:51 -0700
    Re: $0.03 microcontroller lasselangwadtchristensen@gmail.com - 2018-10-10 18:56 -0700
  Re: $0.03 microcontroller Paul Rubin <no.email@nospam.invalid> - 2018-10-10 19:29 -0700
    Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-11 11:39 +0300
      Re: $0.03 microcontroller Paul Rubin <no.email@nospam.invalid> - 2018-10-11 16:08 -0700
        Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-12 08:50 +0200
          Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-12 09:44 +0200
            Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-12 21:30 +0300
              Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-12 22:06 +0200
                Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-12 23:45 +0300
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-13 21:47 +0200
                Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-14 11:58 +0300
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-15 08:14 +0200
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-11-11 09:27 +0100
                Re: $0.03 microcontroller Klaus Kragelund <klauskvik@hotmail.com> - 2018-12-26 02:23 -0800
              Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-15 10:44 +0200
                Re: $0.03 microcontroller Paul Rubin <no.email@nospam.invalid> - 2018-10-15 07:29 -0700
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-16 09:19 +0200
                Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-16 13:48 +0200
                Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-15 21:34 +0300
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-16 09:29 +0200
                Re: $0.03 microcontroller Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2018-10-15 21:22 +0200
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-16 10:00 +0200
                Re: $0.03 microcontroller Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2018-10-16 22:52 +0200
                Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-16 14:01 -0700
                Re: $0.03 microcontroller Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2018-10-17 00:03 +0200
                Re: $0.03 microcontroller Clifford Heath <no.spam@please.net> - 2018-10-17 09:22 +1100
                Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-16 15:29 -0700
                Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-17 00:46 +0200
                Re: $0.03 microcontroller Niklas Holsti <niklas.holsti@tidorum.invalid> - 2018-10-17 09:35 +0300
                Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-17 09:31 +0200
                Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-17 07:08 -0700
                Re: $0.03 microcontroller Niklas Holsti <niklas.holsti@tidorum.invalid> - 2018-10-17 18:37 +0300
                Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-17 10:04 -0700
                Re: $0.03 microcontroller Niklas Holsti <niklas.holsti@tidorum.invalid> - 2018-10-17 23:07 +0300
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-17 08:23 +0200
                Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-17 19:43 +0300
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-17 20:24 +0200
                Re: $0.03 microcontroller George Neuner <gneuner2@comcast.net> - 2018-10-17 11:31 -0400
            Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-11-05 12:41 +0100
          Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-12 09:11 -0700
            Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-13 12:46 +0200
              Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-13 05:06 -0700
                Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-13 18:00 +0300
                Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-13 18:27 +0200
                Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-13 20:50 +0300
                Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-14 14:26 +0200
                Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-13 18:20 -0700
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-14 08:53 +0200
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-14 08:55 +0200
                Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-14 14:32 +0200
                Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-13 18:21 +0200
                Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-13 18:32 -0700
                Re: $0.03 microcontroller Paul Rubin <no.email@nospam.invalid> - 2018-10-13 19:02 -0700
                Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-14 14:37 +0200
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-14 14:59 +0200
                Re: $0.03 microcontroller Paul Rubin <no.email@nospam.invalid> - 2018-10-13 11:06 -0700
            Re: $0.03 microcontroller Niklas Holsti <niklas.holsti@tidorum.invalid> - 2018-10-13 18:31 +0300
              Re: $0.03 microcontroller Niklas Holsti <niklas.holsti@tidorum.invalid> - 2018-10-13 19:46 +0300
                Re: $0.03 microcontroller Niklas Holsti <niklas.holsti@tidorum.invalid> - 2018-10-13 19:59 +0300
                Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-13 21:31 +0300
                Re: $0.03 microcontroller Niklas Holsti <niklas.holsti@tidorum.invalid> - 2018-10-13 22:19 +0300
                Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-13 21:24 +0200
                Re: $0.03 microcontroller Niklas Holsti <niklas.holsti@tidorum.invalid> - 2018-10-13 22:50 +0300
                Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-14 14:39 +0200
                Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-15 05:11 -0700
              Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-13 21:03 +0300
              Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-13 18:25 -0700
          Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-15 14:20 +0200
    Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-21 16:27 +0300
      Re: $0.03 microcontroller jim.brakefield@ieee.org - 2018-10-21 07:47 -0700
        Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-21 08:08 -0700
          Re: $0.03 microcontroller jim.brakefield@ieee.org - 2018-10-21 09:31 -0700
            Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-21 10:51 -0700
              Re: $0.03 microcontroller jim.brakefield@ieee.org - 2018-10-21 12:44 -0700
                Re: $0.03 microcontroller Brett <ggtgp@yahoo.com> - 2018-10-22 00:28 +0000
          Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-21 21:43 +0200
      Re: $0.03 microcontroller Phil Martel <pomartel@comcast.net> - 2018-10-21 11:03 -0400
      Re: $0.03 microcontroller George Neuner <gneuner2@comcast.net> - 2018-10-21 20:59 -0400
  Re: $0.03 microcontroller Michael Kellett <mk@mkesc.co.uk> - 2018-10-11 14:04 +0100
    Re: $0.03 microcontroller David Brown <david.brown@hesbynett.no> - 2018-10-11 15:56 +0200
      Re: $0.03 microcontroller Michael Kellett <mk@mkesc.co.uk> - 2018-10-13 09:35 +0100
        Re: $0.03 microcontroller Paul Rubin <no.email@nospam.invalid> - 2018-10-13 13:06 -0700
          Re: $0.03 microcontroller Michael Kellett <mk@mkesc.co.uk> - 2018-10-14 11:30 +0100
  Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-12 10:18 +0200
    Re: $0.03 microcontroller upsidedown@downunder.com - 2018-10-12 21:39 +0300
      Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-11-08 13:53 +0100
        Re: $0.03 microcontroller Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-11-08 15:08 +0200
          Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-11-08 14:34 +0100
        Re: $0.03 microcontroller upsidedown@downunder.com - 2018-11-08 21:52 +0200
          Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-11-08 21:56 +0100
            Re: $0.03 microcontroller upsidedown@downunder.com - 2018-11-09 00:35 +0200
              Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-11-09 09:00 +0100
    Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-15 14:19 +0200
  Re: $0.03 microcontroller Tim <cpldcpu+usenet@gmail.com> - 2018-10-14 01:46 +0200
    Re: $0.03 microcontroller Theo <theom+news@chiark.greenend.org.uk> - 2018-10-14 10:55 +0100
      Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-24 15:57 +0200
  Re: $0.03 microcontroller Philipp Klaus Krause <pkk@spth.de> - 2018-10-15 14:35 +0200
    Re: $0.03 microcontroller raimond.dragomir@gmail.com - 2018-10-15 06:05 -0700
      Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-15 07:19 -0700
        Re: $0.03 microcontroller Paul Rubin <no.email@nospam.invalid> - 2018-10-15 07:26 -0700
          Re: $0.03 microcontroller gnuarm.deletethisbit@gmail.com - 2018-10-15 07:30 -0700

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