Floppy Partionning system

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Re: Floppy Partionning system

Postby VladVP » Tue Nov 05, 2013 5:50 pm

lamogui wrote:
VladVP wrote:Yeah! What's wrong with just assuming that the programmer put a bootloader in the first sector, and copy that entire sector into RAM? It's as simple as that! Why does the BIOS suddenly have to handle file systems?


This is limiting the size of the program to 512 words !


.............

How is only loading 512 words equivalent to limiting the total size of the program?

http://en.wikipedia.org/wiki/Booting
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Re: Floppy Partionning system

Postby lamogui » Tue Nov 05, 2013 6:26 pm

VladVP wrote:How is only loading 512 words equivalent to limiting the total size of the program?
http://en.wikipedia.org/wiki/Booting


Sorry maybe i didn't understand very well what you mean...
If i understand you mean that the bios sould just load the first sector of the floppy into the ram, but the 1st sector is only 512words so i mean this program (located in the 1 sector) will be limited to 512 words. So that's mean that the programmer who want to create a bigger program will need to load the rest from the floppy itself, and i think it's a bad idea...
please correct my english errors
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Re: Floppy Partionning system

Postby VladVP » Tue Nov 05, 2013 9:43 pm

lamogui wrote:i think it's a bad idea...


Well, then you should probably complain to Konrad Zuse himself. The process is called booting, and the 512-word program is the boot loader. Every single widely used system in the world uses boot loading; especially old systems from the 80's.
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Re: Floppy Partionning system

Postby DarkSpartan » Wed Nov 06, 2013 12:10 am

lamogui wrote:
VladVP wrote:Yeah! What's wrong with just assuming that the programmer put a bootloader in the first sector, and copy that entire sector into RAM? It's as simple as that! Why does the BIOS suddenly have to handle file systems?


This is limiting the size of the program to 512 words !


There's that assumption thing again. The chances of the Notch spec being implemented (as written) is vanishingly small. There's a reason I called for a huge conversation about the ship's computer.
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Re: Floppy Partionning system

Postby Zardoz » Wed Nov 06, 2013 6:57 am

http://en.wikipedia.org/wiki/Booting#Bo ... ompatibles
512 Bytes is enough to create a basic bootloader and loads all from the disk. Think that this add flexibility as the BIOS not need to know anything about file systems, partitions ,etc... It search for a sector 0 marked to be bootable.
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Re: Floppy Partionning system

Postby VladVP » Wed Nov 06, 2013 7:07 am

Zardoz wrote:http://en.wikipedia.org/wiki/Booting#Boot_sequence_of_IBM-PC_compatibles
512 Bytes is enough to create a basic bootloader and loads all from the disk. Think that this add flexibility as the BIOS not need to know anything about file systems, partitions ,etc... It search for a sector 0 marked to be bootable.

So now we only need 256 words for a boot loader? That's even better, but... how big should the span of memory that the BIOS is going to load actually supposed to be? A minimal boot loader can't be much more than 30-50 instructions long...
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Re: Floppy Partionning system

Postby Cryptix » Wed Nov 06, 2013 1:58 pm

I can't see a BIOS being bigger than 30KB (30x 512 word sectors), not for a computer this old, and if the BIOS is bigger then make the bootloader load a secondary and much larger bootloader that can boot the entire BIOS.
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Re: Floppy Partionning system

Postby Zardoz » Wed Nov 06, 2013 4:39 pm

The Amiga 1000 (1985 computer) has a ROM of 256 KiB (include half of the lowest layer of the OS) and the original IBM PC had 64KiB ROM (include a BASIC interpreter).
The Atari ST 520ST had a 16 KiB ROM.

I think that 64KiB for the BIOS is enough to doing interesting things, like including a BASIC interpreter or include some basic DOS like OS.

BIOS size isn't related to the sector size , Cryptix.
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Re: Floppy Partionning system

Postby VladVP » Wed Nov 06, 2013 5:25 pm

Cryptix wrote:I can't see a BIOS being bigger than 30KB (30x 512 word sectors), not for a computer this old, and if the BIOS is bigger then make the bootloader load a secondary and much larger bootloader that can boot the entire BIOS.

wat.

I'm not even understanding what you're saying anymore... so we're supposed to have a BIOS load a boot loader which loads a BIOS which loads a boot loader? Perhaps you meant that the boot loader was supposed to boot an OS?
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Re: Floppy Partionning system

Postby S0lll0s » Wed Nov 06, 2013 6:38 pm

lamogui wrote:
VladVP wrote:Yeah! What's wrong with just assuming that the programmer put a bootloader in the first sector, and copy that entire sector into RAM? It's as simple as that! Why does the BIOS suddenly have to handle file systems?


This is limiting the size of the program to 512 words !

A bootloader / strapper easily fits into 512 words.

I would however include a flashable BIOS that is copied into RAM on poweron, (512w would be fine) that can only be flashed with some sort of cost (power, money, resources)
As you might have noticed, I'm a fan of forcing people to invent stuff, and this would make an OS neccessary if you want to do cool stuff.
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