Groups > alt.folklore.computers > #161777

Re: Which Books Can You Recommend For Learning Computer Programming?

From	Bob Eager <news0006@eager.cx>
Newsgroups	alt.folklore.computers
Subject	Re: Which Books Can You Recommend For Learning Computer Programming?
Date	2016-04-01 13:02 +0000
Message-ID	<dm79qjFflomU29@mid.individual.net> (permalink)
References	(6 earlier) <87shz8dir2.fsf@roadgrime.nodomain.nowhere> <PM00052F44B0C5159C@aca40b23.ipt.aol.com> <h3SKy.73542$6%.47175@fx02.iad> <PM00052F5735FAA37D@aca4282e.ipt.aol.com> <Jh9Ly.113899$X_.106447@fx04.iad>

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On Thu, 31 Mar 2016 13:06:49 +0000, Scott Lurndal wrote:

> jmfbahciv <See.above@aol.com> writes:
>>Scott Lurndal wrote:
> 
>>> why bother with ancient architectures, when one can obtain much more
>>> relevent data using modern processors and software?
>>
>>The machine code is readable and word oriented.
> 
> There are no word machines in common use today.  All are byte machines. 
> Therefore, there is no reason that one would prefer a word-oriented
> machine as a learning tool (and if there was,
> I'd recommmend the Unisys clearpath libra architecture based on the
> B6500 which would be far less useless today as the PDP-10, since there
> are still libra's in production and need for programmers).
> 
> X86 assembler is readable as well.  You have never even used it,
> how can you reject it so casually?
> 
> 00000000005d22e6 <c_condition::timedwait(c_lock*, timespec*)>:
>   5d22e6:       55                      push   %rbp 5d22e7:       48 89
>   e5                mov    %rsp,%rbp 5d22ea:       48 83 ec 20          
>     sub    $0x20,%rsp 5d22ee:       48 89 7d f8             mov   
>   %rdi,-0x8(%rbp)
>   5d22f2:       48 89 75 f0             mov    %rsi,-0x10(%rbp)
>   5d22f6:       48 89 55 e8             mov    %rdx,-0x18(%rbp)
>   5d22fa:       48 8b 4d f0             mov    -0x10(%rbp),%rcx 5d22fe: 
>        48 8b 45 f8             mov    -0x8(%rbp),%rax 5d2302:       48
>   8b 55 e8             mov    -0x18(%rbp),%rdx 5d2306:       48 89 ce   
>               mov    %rcx,%rsi 5d2309:       48 89 c7                mov
>      %rax,%rdi 5d230c:       e8 8f 0f ea ff          callq  4732a0
>   <pthread_cond_timedwait@plt> 5d2311:       c9                     
>   leaveq 5d2312:       c3                      retq 5d2313:       90    
>                    nop
> 
> Looks a lot like the PDP-11, in fact.

It may LOOK like it - but nothing like. The PDP-11 is moderately 
orthogonal - the x86 isn't. PDP-11 instructions mostly work with any 
source and destination - the x86 ones don't.

> 
> And here's arm aarch64:
> 
> 0000000000401570 <register_tm_clones>:
>   401570:       b0000081        adrp    x1, 412000
>   <__frame_dummy_init_array_entry>
>   401574:       b0000080        adrp    x0, 412000
>   <__frame_dummy_init_array_entry>
>   401578:       910ae021        add     x1, x1, #0x2b8 40157c:      
>   910ae000        add     x0, x0, #0x2b8 401580:       58000187       
>   ldr     x7, 4015b0 <register_tm_clones+0x40> 401584:       cb000021   
>       sub     x1, x1, x0 401588:       9343fc21        asr     x1, x1,
>   #3 40158c:       8b41fc21        add     x1, x1, x1, lsr #63 401590:  
>       9341fc21        asr     x1, x1, #1 401594:       eb1f003f       
>   cmp     x1, xzr 401598:       fa5f10e4        ccmp    x7, xzr, #0x4,
>   ne 40159c:       54000060        b.eq    4015a8
>   <register_tm_clones+0x38>
>   4015a0:       d61f00e0        br      x7 4015a4:       d503201f       
>   nop 4015a8:       d65f03c0        ret 4015ac:       d503201f       
>   nop
> 
> To me, the x86 is more readable.  YMMV.

It certainly does. And I have used a dozen different assembly languages, 
at an absolute minimum.

-- 
Using UNIX since v6 (1975)...

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