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Re: Sample ARM assember code?

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On 2016-11-24, Jeff Jonas <jeffj@panix.com> wrote:
>>> That's part of the 'culture shock' of going to pure RISC.
>>> Only one memory access per instruction.
>>> No memory to memory accesses, searches, etc.
>
>> old-school assembly programmers were used to that,
>> particularly on things like 6502 and really old minicomputers
>> that only had accumulators and index registers.
>
> The 6502 was not so bad.
> It had fewer registers than the Motorola 6800
> to reduce die size and complexity, thus the lower cost
> but it still had index registers that could be used
> almost as well as general purpose registers.
>
> It even had SOME memory-to-memory operations.
> Citing http://forum.6502.org/viewtopic.php?t=2
>
>     Read-modify-write instructions (like INC)
>     read the original data, write it back, and then write the modified data.
>
> -- jeffj

I was told a different reason the 6502 has fewer registers and
such than the 6800--IIRC, either in class or in conversation
while I was in college.  I was told that the 6502 originally was
going to have wider (16-bit, IIUC) index registers and more
instructions, but Motorola threatened to sue because of
similarity to either the 6800 or 6809, and the 6502 feature set
was reduced to avoid being sued.  IIUC, some of the 6502
designers had worked at Motorola, and Motorola claimed they were
taking Motorola IP in the original design of the 6502.

My experience was that after programming the 6809 with its 16-bit
index registers, the 6502 was underwhelming.  One time, I coded
up a homework assignment in assembler for 6502, 6800, and 6809.
The 6502 took the largest number of instructions.  The 6800 took
two-thirds as many as the 6502.  The 6809 took half as many as
the 6502.

HTH

-- 
Robert Riches
spamtrap42@jacob21819.net
(Yes, that is one of my email addresses.)

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Sample ARM assember code? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-06 11:25 +0100
  Re: Sample ARM assember code? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-07-06 13:54 +0300
    Re: Sample ARM assember code? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-06 12:50 +0100
      Re: Sample ARM assember code? alister <alister.ware@ntlworld.com> - 2016-07-06 12:29 +0000
        Re: Sample ARM assember code? alister <alister.ware@ntlworld.com> - 2016-07-06 12:46 +0000
          Re: Sample ARM assember code? "Kerr Mudd-John" <admin@127.0.0.1> - 2016-07-06 14:15 +0100
        Re: Sample ARM assember code? Dennis <dennis@none.none> - 2016-07-06 10:08 -0500
      Re: Sample ARM assember code? jeffj@panix.com (Jeff Jonas) - 2016-07-06 08:39 -0400
        Re: Sample ARM assember code? Big Bad Bob <BigBadBob-at-mrp3-dot-com@testing.local> - 2016-10-13 01:17 -0700
          Re: Sample ARM assember code? Michael J. Mahon <mjmahon@aol.com> - 2016-10-13 11:48 -0500
            Re: Sample ARM assember code? jeffj@panix.com (Jeff Jonas) - 2016-11-24 02:19 -0500
          Re: Sample ARM assember code? jeffj@panix.com (Jeff Jonas) - 2016-11-24 01:56 -0500
            Re: Sample ARM assember code? Robert Riches <spamtrap42@jacob21819.net> - 2016-11-25 03:36 +0000
              Re: Sample ARM assember code? Michael J. Mahon <mjmahon@aol.com> - 2016-11-24 23:31 -0600
                Re: Sample ARM assember code? alister <alister.ware@ntlworld.com> - 2016-11-25 12:42 +0000
                Re: Sample ARM assember code? The Natural Philosopher <tnp@invalid.invalid> - 2016-11-25 13:14 +0000
                Re: Sample ARM assember code? Robert Riches <spamtrap42@jacob21819.net> - 2016-11-26 01:05 +0000
                Re: Sample ARM assember code? The Natural Philosopher <tnp@invalid.invalid> - 2016-11-26 11:28 +0000
                Re: Sample ARM assember code? Robert Riches <spamtrap42@jacob21819.net> - 2016-11-27 03:32 +0000
                Re: Sample ARM assember code? The Natural Philosopher <tnp@invalid.invalid> - 2016-11-27 12:01 +0000
                Re: Sample ARM assember code? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-11-27 09:28 -0500
              Re: Sample ARM assember code? mm0fmf <none@invalid.com> - 2016-11-25 18:06 +0000
  Re: Sample ARM assember code? glavallin <glavallin@gjlavallin.plus.com> - 2016-10-27 10:07 +0100
    Re: Sample ARM assember code? glavallin <glavallin@gjlavallin.plus.com> - 2016-10-27 10:39 +0100
    Re: Sample ARM assember code? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-10-27 12:30 +0300

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