Groups | Search | Server Info | Login | Register

Groups > comp.sys.acorn.programmer > #6522

Re: File type of machine code? Where does it start?

Show all headers | View raw

In message <5c2f4363e6bavariasound@chiemgau-net.de>
          Alexander Ausserstorfer <bavariasound@chiemgau-net.de> wrote:

> In article <5c29d67fbebavariasound@chiemgau-net.de>,
>    Alexander Ausserstorfer <bavariasound@chiemgau-net.de> wrote:
>> In article <lKm*MFveA@news.chiark.greenend.org.uk>,
>>    Theo <theom+news@chiark.greenend.org.uk> wrote:
>>> Alexander Ausserstorfer <bavariasound@chiemgau-net.de> wrote:


>>>> Where do I find the starting point of such a code? What is the address
>>>> where the machine code is starting?

>>> This is the territory of executable formats.

>> [...]

>> Many thanks! I found the Appendix D: Code file formats in RISC OS 3
>> Programmer's Reference Manual Volume 4. I'm not sure if I will
>> understand that all. It's a shame that I never read about that in the
>> GAG-News or any other publication in a clear understandable way.

> I created a new file in !StrongEd and saved it with file type
> "application". You can change the file type while saving the file to
> anywhere. Then opened the file again. It may be required to chance the
> mode to 'dump'. Clicked on 'byte'. Now you can write the commands like
> you wish. The last command should always be E0 F0 A0 E1. Then saved the
> file and started it by a double click. You can add the command 00 00 A0
> E1 (what is doing nothing of course) before. And so on.

> I have no idea, why 'word' and 'byte' are reversed. When you click on
> word, you have to write

> E1 A0 00 00
> E1 A0 F0 E0

> of course. This is the format it is descripted in the manual of the ARM
> (Arm A32/T32 Instrution Set for A-profile architecture) I have here.

endianess
https://en.wikipedia.org/wiki/Endianness

From DDE.Codestds.AOF
There are two sorts of AOF: <little-endian> and <big-endian>.

In little-endian AOF, the least significant byte of a word or half-word 
has the lowest address of any byte in the (half-)word. This <byte sex> is 
used by DEC,Intel and Acorn, amongst others.

In big-endian AOF, the most significant byte of a (half-)word has the 
lowest.address. This byte sex is used by IBM, Motorola and Apple, amongst 
others.

> Thank you very much for all your help here.

> A.
> A.



-- 
Jean-Michel

Back to comp.sys.acorn.programmer | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

File type of machine code? Where does it start? Alexander Ausserstorfer <bavariasound@chiemgau-net.de> - 2025-06-07 17:41 +0200
  Re: File type of machine code? Where does it start? Martin <News03@avisoft.f9.co.uk> - 2025-06-07 18:14 +0100
    Re: File type of machine code? Where does it start? Alexander Ausserstorfer <bavariasound@chiemgau-net.de> - 2025-06-08 18:26 +0200
  Re: File type of machine code? Where does it start? Theo <theom+news@chiark.greenend.org.uk> - 2025-06-08 11:02 +0100
    Re: File type of machine code? Where does it start? Alexander Ausserstorfer <bavariasound@chiemgau-net.de> - 2025-06-08 18:32 +0200
      Re: File type of machine code? Where does it start? Alexander Ausserstorfer <bavariasound@chiemgau-net.de> - 2025-06-19 07:22 +0200
        Re: File type of machine code? Where does it start? Jean-Michel <jmc.bruck@orange.fr> - 2025-06-19 11:23 +0200
          Re: File type of machine code? Where does it start? druck <news@druck.org.uk> - 2025-06-24 20:47 +0100
            Re: File type of machine code? Where does it start? Bob Latham <bob@sick-of-spam.invalid> - 2025-06-25 09:29 +0100
        Re: File type of machine code? Where does it start? Martin <News03@avisoft.f9.co.uk> - 2025-06-19 10:48 +0100
          Re: File type of machine code? Where does it start? Alexander Ausserstorfer <bavariasound@chiemgau-net.de> - 2025-06-20 17:22 +0200
            Re: File type of machine code? Where does it start? Matthew Phillips <spam2011m@yahoo.co.uk> - 2025-06-21 08:20 +0100
        Re: File type of machine code? Where does it start? Theo <theom+news@chiark.greenend.org.uk> - 2025-06-20 17:25 +0100

csiph-web