Authored by: Wol on Friday, December 28 2012 @ 03:54 PM EST |
Depends what you mean.
When you switch on a PC, part of the startup circuitry sends
a hard reset to the CPU. This sets the program counter to
zero or some other FIXED address, where a ROM (EEPROM,
Flash, whatever) chip is located.
On all PCs up to the present (UEFI possibly excepted) this
is the BIOS chip, which starts up the computer. This then
may invoke BASIC, or read the OS from disk, or whatever.
DOS, being very basic, made extensive use of calls into the
BIOS. This implies the BIOS was, probably still is!, 16-bit.
Windows 95, and quite likely Windows 3, if not even earlier,
completely ignores the bios once it's loaded, and duplicates
the bios' functionality (as linux has done, right from the
start).
As I understand it (quite likely wrongly :-) UEFI is likely
a 64-bit operating system, in Flash, at the CPU startup
location. One of the options it has, is to chain into bios,
if that's what you want.
The problem with Win8 is that it *may* (and *is* on ARM)
coded to call UEFI and ask "have I been loaded securely?".
If UEFI has chained into bios, that answer is "no", at which
point Win8 refuses to load. (Or, on ARM, that option for
bios is not there.)
Cheers,
Wol[ Reply to This | Parent | # ]
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- UEFI vs. EFI - Authored by: myNym on Friday, December 28 2012 @ 04:38 PM EST
- UEFI vs. EFI - Authored by: Anonymous on Saturday, December 29 2012 @ 03:26 AM EST
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