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Groups > comp.os.msdos.programmer > #908

Re: Use of BIOS calls by various OSes, bootloaders, etc., online references

From "wolfgang kern" <nowhere@never.at>
Newsgroups alt.os.development, comp.os.msdos.programmer, comp.os.msdos.misc
Subject Re: Use of BIOS calls by various OSes, bootloaders, etc., online references
Date 2013-05-21 21:16 +0200
Organization KESYS-development
Message-ID <kngiak$7uo$2@newsreader2.utanet.at> (permalink)
References <knepcr$bco$1@speranza.aioe.org>

Cross-posted to 3 groups.

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Rod Pemberton wrote:

> The general issue of whether BIOS calls are important or not to
> bootloaders and OS development came up recently on
> alt.os.development.
...
A bootloader should check on A20_on and INT13.41 for ext. HD-read.
Mem-map info from E820 may help a bit but cant tell available PCI-RAM.
Anything else (today) like default Vmode==03 and all addon-hw-features
are disabled until the OS enables it are almost standard BIOS-default.

So my vital (only used once in Boot-sequence) BIOS calls are:
13/41..42   ;check for ext HD-access
10/4F/00/01 ;VBIOS: detect VESA and check for supported modes.
15/e820     ;memmap even not really a complete info to be found here.
15/..       ;assumed that the BIOS set monitor speed accordingly.

all other hw-checks are part of the hw-detection module within
the later in PM running OS-core (bypass/ignore all BIOS).
__
wolfgang

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Thread

Use of BIOS calls by various OSes, bootloaders, etc., online references "Rod Pemberton" <do_not_have@notemailnotq.cpm> - 2013-05-20 23:27 -0400
  Re: Use of BIOS calls by various OSes, bootloaders, etc., online references "wolfgang kern" <nowhere@never.at> - 2013-05-21 21:16 +0200
  Re: Use of BIOS calls by various OSes, bootloaders, etc., online references Ross Ridge <rridge@csclub.uwaterloo.ca> - 2013-05-23 18:38 -0400

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