Re: Apollo 11 source code released

From	Alain Fournier <alain245@videotron.ca>
Newsgroups	sci.space.policy
Subject	Re: Apollo 11 source code released
Date	2016-07-11 19:43 -0400
Organization	A noiseless patient Spider
Message-ID	<nm1av6$uek$1@dont-email.me> (permalink)
References	<57827b36$0$12019$c3e8da3$3a1a2348@news.astraweb.com> <duff7pF91l8U1@mid.individual.net> <5782cc04$0$20011$c3e8da3$1cbc7475@news.astraweb.com> <p2j6obt05vvmbg0i08afngatpmurap66e6@4ax.com> <MPG.31ed42b4228b7dbc98979b@news.eternal-september.org>

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Le Jul/11/2016 à 6:44 AM, Jeff Findley a écrit :
> In article <p2j6obt05vvmbg0i08afngatpmurap66e6@4ax.com>,
> fjmccall@gmail.com says...
>>
>> JF Mezei <jfmezei.spamnot@vaxination.ca> wrote:
>>
>>> On 2016-07-10 13:33, Niklas Holsti wrote:
>>>
>>>> A custom-made computer:
>>>>
>>>> https://en.wikipedia.org/wiki/Apollo_Guidance_Computer
>>>
>>>
>>> Very interesting read. Thanks.  It mentions it was the first computer
>>> made of integrated circuits. Looks like it was all fixed decimal
>>> notation as opposed to floating point. That would have a big impact on
>>> the heavy math done for guidance and navigation (lots of angles/trig etc).
>>>
>>> Was all the code written in assembler or were portions done in higher
>>> level languages ?
>>>
>>
>> No HOL.  Have you looked at the specifications for these things?
>
> The Wikipedia entry clearly says this, "AGC software was written in AGC
> assembly language and stored on rope memory."
>
> By modern standards, we really don't have much to compare with.  Going
> back to the 1980's, the AGC was about twice the speed of my old C-64 but
> with only a tiny fraction of the RAM and a lot more more ROM (since
> there was no other place for program storage like tape or disk).
>
> Putting it in that perspective, the C-64 programs written commercially
> rarely used languages above assembly language.  You just could not do
> much on a C-64 using a "higher level language" due to the overhead of
> incurred.

No, that would be under using the C-64. The 64 in C-64 standed for 64 
kilobytes. But that was a little bit of a misnomer. You had 80 kilobytes 
of memory. The 64 kb of RAM but also 16 kb of ROM. You had to switch the 
16 kb of ROM/RAM to access one or the other. You could save some 
precious RAM by using the basic interpreter in the 16 kb of ROM. If I 
recall correctly it was a bit on byte number 1 that would be used as a 
switch to access the ROM or the underlying RAM. I wrote a program that 
could not have fit in 64 kb of RAM, but could be squeezed into the C-64 
by switching between the two memory modes. Even then, I had a hard time 
making it fit into the memory space. I had to cleverly chose where some 
parts of the program were placed in order to have an assembler jump 
instruction (a goto if you prefer) at the end of a section of code have 
just the right jump address so the next section of code could start with 
the last byte of the jump address.
So that was three bytes for the jump instruction, the jump instruction 
was one byte and the address where to jump two bytes, therefore it was
jumpto byte1byte2. But the next section of code started with an 
instruction, I think it was load into registry, but the important point 
is that this instruction's binary code was equal to the byte2 of the 
jump instruction, so byte2 was used both as an address where to jump and 
as an instruction. It took me a month to figure out how to do it but 
that single saved byte allowed me to fit my program in the 80 kb of the 
C-64.
Now that I use a computer with 24 Tera-bytes of RAM, I no longer work as 
hard to save a single byte.

Alain Fournier

Thread

Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-10 12:43 -0400
  Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-10 20:33 +0300
    Re: Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-10 18:28 -0400
      Re: Apollo 11 source code released Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-07-10 21:27 -0400
      Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-11 00:36 -0700
        Re: Apollo 11 source code released Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-07-11 06:44 -0400
          Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-11 16:20 +0300
            Re: Apollo 11 source code released Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-07-11 20:53 -0400
              Re: Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-12 14:36 -0400
                Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-12 18:11 -0700
              Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-12 23:37 +0300
                Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-12 18:14 -0700
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-13 21:01 +0300
                Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-13 20:06 -0700
                Re: Apollo 11 source code released Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-07-14 06:44 -0400
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-15 23:54 +0300
                Re: Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-17 11:49 -0400
                Re: Apollo 11 source code released William Mook <mokmedical@gmail.com> - 2016-07-17 18:41 -0700
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-18 09:20 +0300
                Re: Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-14 11:38 -0400
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-16 00:10 +0300
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-15 22:26 +0300
                Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-20 10:49 -0700
              Re: Apollo 11 source code released Snidely <snidely.too@gmail.com> - 2016-07-14 09:12 -0700
          Re: Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-11 11:51 -0400
            Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-12 02:19 +0300
              Re: Apollo 11 source code released Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-07-11 20:58 -0400
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-12 09:24 +0300
                Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-12 10:10 -0700
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-13 21:07 +0300
                Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-13 20:08 -0700
                Re: Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-14 11:25 -0400
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-15 22:39 +0300
                Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-20 10:40 -0700
                Re: Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-12 14:41 -0400
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-12 23:26 +0300
                Re: Apollo 11 source code released Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-07-12 21:41 -0400
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-13 08:54 +0300
                Re: Apollo 11 source code released Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-07-13 06:43 -0400
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-13 21:08 +0300
                Re: Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-14 11:34 -0400
                Re: Apollo 11 source code released Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-07-15 23:06 +0300
                Re: Apollo 11 source code released Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-07-15 19:48 -0400
                Re: Apollo 11 source code released Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-07-15 19:59 -0400
                Re: Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-17 12:00 -0400
                Re: Apollo 11 source code released Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-07-17 12:14 -0400
                Re: Apollo 11 source code released JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-07-17 12:56 -0400
              Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-12 10:04 -0700
            Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-12 09:43 -0700
          Re: Apollo 11 source code released Alain Fournier <alain245@videotron.ca> - 2016-07-11 19:43 -0400
  Re: Apollo 11 source code released Fred J. McCall <fjmccall@gmail.com> - 2016-07-10 11:39 -0700
  Re: Apollo 11 source code released William Mook <mokmedical@gmail.com> - 2016-07-11 18:28 -0700

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