Call me dumb? but...

[Linkin' Park]

I was wondering when does windows start? the boot up of your pc is in dos, but isn't dos as windows code? or does the motherboard have dos hardwired into it? like bios isn't that dos based. Basically all im asking does windows start as soon as u press that power button?

Thanks

p.s i won't mind if you fink im dumb! :(

[vibe666]

I'm by no means an expert but this is how I see it.

DOS stands for 'Disk Operating System' and since the first thing (in most cases) you see is the details of your video card when it initializes and then you see your BIOS runs it's POST 'Power On Self Test' (checking for errors, the presence of HD,FD,CDROM, RAM, Keyboard & Mouse etc.) and this all happens before the hard drive is even accessed then your BIOS can't be DOS based can it? IMHO.

i don't think i really cleared anything up there did i?

anyway, Win95 & 98 both have their roots firmly in MS DOS territory and although they are a lot fancier and feature rich than say Win 3.11 they still sit on top of what is basically DOS 6.22 to do all their work.

Win NT4 works differently (i don't have much of an idea how differently) and AFAIK was built from the ground up to do away with the command line DOS that was used up until then (by the time I got into PC's NT 3.51 was long gone so don't ask me about that. maybe someone else can fill in the gaps) and was made with security and stability at its core to make it the most suitable OS for businesses and kill off the competition.

and again AFAIK Win2000 and XP both use an advanced version of the the core of what was Windows NT.

But given the meaning of 'DOS' i suppose they are all DOS even though somewhere along the line they dropped the 'D' and now just call them all OS's.

perhaps they did this to avoid confusion, who really knows. whatever the reason they didn't count on me making even more confusing did they?

My work here is done :D

where was i again?

[JMBurton2001]

I sincerely hope you're not playing everybody....

I'll give this a try, here goes a simplified version...

When you press the power button the first thing that happens is a POST (Power On Self Test) of the motherboard and BIOS (Basic Input Output System). Then the hardware layer is setup based on the peripherals attached to the board, IRQ's and DMA's are assigned as needed. The memory is tested. This is NOT DOS and will occur whether you have DOS (or any operating system) or not.

If you make it past here, the BIOS looks for an OS (Operating System) in the place you've specified in the BIOS setup. Most likely your floppy drive or your primary hard drive. This could be DOS, OS/2, NT (Whatever flavor 2K, ME, XP...) Linux, Unix, etc...

DOS (or whatever OS) starts to load at this point. The hardware abstraction layer of whatever OS you're using is the glue that binds the physical hardware to the software and makes everything interoperate correctly.

[Rugor]

Ok speaking for the Win9x kernel--IE Win95, 98, ME the general sequence is this

First the POST:

--Power On Self Test

This is where the system checks to see everything is working.

Then the BIOS loads

--Basic Input Output System

The bios is what tells your system how to do basic tasks like read a Hard Drive.

Once the BIOS has loaded the system begins loading what are called real-mode drivers. These are 16bit Dos-based drivers that serve to prepare the system to load Windows.

Once these have loaded the system switches to 32bit "protected mode" and starts loading Windows proper.

It's called "booting" because it's essentially a bootstrap process with each level serving to enable the next one to load.

This is very much simplified but it's a basic overview of how it works.

POST ------->BIOS------->Real Mode(16-bit DOS)--------->Protected Mode(32-bit Windows)

[Linkin' Park]

so bios is dos?

[Rugor]

Linkin,

No, BIOS is Not DOS, it comes before DOS

BIOS is what the system uses to find the Hard Drive and start to load DOS.

[Linkin' Park]

yeah but what sort of system is bios then, has the mb got its own???

[Vernon Frazee]

In order for most computer (http://www.webopedia.com/TERM/c/computer.html) hardware (http://www.webopedia.com/TERM/h/hardware.html) to function, it must follow a set of coded (http://www.webopedia.com/TERM/c/code.html) instructions, called software (http://www.webopedia.com/TERM/s/software.html). A PC (http://www.webopedia.com/TERM/P/PC.html)'s BIOS (http://www.webopedia.com/TERM/B/BIOS.html) is built-in software that determines what a computer can do before it loads an Operating System (http://www.webopedia.com/TERM/o/operating_system.html). The BIOS contains the software required to control the keyboard (http://www.webopedia.com/TERM/B/keyboard.html), display screen (http://www.webopedia.com/TERM/B/display_screen.html), disk drives (http://www.webopedia.com/TERM/B/disk_drive.html), communication (http://www.webopedia.com/TERM/c/communications.html) ports (http://www.webopedia.com/TERM/p/port.html) and other miscellaneous functions (http://www.webopedia.com/TERM/f/function.html).

Normally, all of the software programs that you run (http://www.webopedia.com/TERM/r/run.html) on your PC are stored on a hard disk (http://www.webopedia.com/TERM/h/hard_disk.html) and then loaded (http://www.webopedia.com/TERM/l/load.html) into your computers system memory (http://www.webopedia.com/TERM/m/memory.html) (RAM (http://www.webopedia.com/TERM/R/RAM.html)) when you need to use them. The processor (http://www.webopedia.com/TERM/p/processor.html) (CPU (http://www.webopedia.com/TERM/C/CPU.html)) then accesses and runs the software instructions from memory, which lets you do your work.

When you first turn on your PC, the processor needs some instructions to execute (http://www.webopedia.com/TERM/e/execute.html). Since you just turned it on however, your system's memory is still empty; there are no instructions to execute. To make sure that the BIOS instructions are always available to the processor, even when it is first turned on, the BIOS software is typically placed in a ROM (http://www.webopedia.com/TERM/R/ROM.html) chip (http://www.webopedia.com/TERM/c/chip.html) on the motherboard (http://www.webopedia.com/TERM/m/motherboard.html) (often called a ROM BIOS). This ensures that the BIOS will always be available and will not be damaged by disk failures. It also makes it possible for a computer to boot (http://www.webopedia.com/TERM/b/boot.html) itself.

A uniform standard was created between the makers of processors and the makers of BIOS programs, so that the processor would always look in the same place in memory to find the start of the BIOS program. This special reserved memory area is in the upper 64KB (http://www.webopedia.com/TERM/K/KB.html) of the first MB (http://www.webopedia.com/TERM/M/MB.html) of system memory (addresses F000h to FFFFh). (Note that some BIOSes use more than this 64KB area).

The processor gets its first instructions from this location, and the BIOS program begins executing. The BIOS program then begins the system boot sequence which calls other programs that get your operating system loaded and your PC up and running.

Many modern PCs have a flash BIOS, which means that the BIOS has been recorded on a flash memory (http://www.webopedia.com/TERM/B/flash_memory.html) chip, which can be updated if necessary. PC BIOSes that can handle Plug-and-Play (PnP) (http://www.webopedia.com/TERM/B/PnP.html) devices (http://www.webopedia.com/TERM/B/device.html) are known as PnP BIOSes, or PnP-aware BIOSes. These BIOSes are always implemented with flash memory rather than ROM.

Note that most BIOS Setup programs still use a character-based (http://www.webopedia.com/TERM/c/character_based.html) (versus a graphics-based (http://www.webopedia.com/TERM/g/graphics_based.html)) interface simply because of the limited amount of storage space within the ROM chip.

Sources:

PCGuide.com > System BIOS (http://www.pcguide.com/ref/mbsys/bios/index.htm)
Webopedia.com > BIOS (http://www.webopedia.com/TERM/B/BIOS.html)

[Strawbs]

WOW!!:eek:

And now to thoroughly Over-Cook the Goose. :D

BIOS (Boot ROM) is a small program, loaded into a chip (probably covered with a flashy looking sticky label) which is plugged into your MoBo (hence a corrupted BIOS will stop your Computer Booting). There is also a BIOS program on your Graphics card. The O\S or "Operating System", Be it DOS, Windows O\S, Mac O\S, Linux O\S or any other O\S, is Loaded on your hard disc which is read after the BIOS' do thier thang, i.e checking hardware is powered up, where it should be and working\communicating OK.

The Correct order should be:
1.Graphics BIOS,
2.Boot ROM BIOS,
3.Primary Hardware (Keyboard,Mouse,RAM,Hard Discs,CD Drives,Floppys et al),
4.O\S (inc. MS DOS),
5.Secondary Hardware (Sound card, Printer,Scanner,Modem and any other O\S reliant hardware)


Ba Da Bing ... :)

P.S. I Love these "Call me dumb but ..." Posts :D and with 148 posts to his name, Linkin' has to be playing with us.

[rlpos]

I think we had a similar discussion a while ago. See Link http://www.sysopt.com/forum/showthread.php?s=&threadid=71367&highlight=dos