Linked by Thom Holwerda on Wed 18th May 2011 21:50 UTC, submitted by fran
Windows The ARM version of Windows 8 might have just become the most desired version of Windows in our hearts and minds. After us talking about legacy code and backwards compatibility in Windows for years now, an Intel senior vice president, Renee James, has just stated that Windows 8 on ARM will not have any form of compatibility for legacy applications whatsoever. Update: Microsoft has responded to Intel's claims. "Intel's statements during yesterday's Intel Investor Meeting about Microsoft's plans for the next version of Windows were factually inaccurate and unfortunately misleading," the company said, "From the first demonstrations of Windows on SoC, we have been clear about our goals and have emphasized that we are at the technology demonstration stage. As such, we have no further details or information at this time."
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Wouldn't be nice for Intel to start cutting off some old, unsupported instructions and enhance greatly x86 with this news version of Windows. I mean, if Windows 8 is breaking backward compatibility by requiring a Windows 7 layer, that layer could support some kind of emulation on the new chips. Dropping real mode and old, unused instructions could free up some nice space on the sillicon.

Take that with a grain of salt, but I think I've read somewhere that on modern x86 chips, real mode is emulated anyway, so you'd only save some kB of ROM.

Plus, you still need real mode for some fairly useful BIOS instructions and extensions.

Edited 2011-05-19 12:31 UTC

Reply Parent Score: 1

toast88 Member since:

Take that with a grain of salt, but I think I've read somewhere that on modern x86 chips, real mode is emulated anyway, so you'd only save some kB of ROM.

I guess you are talking about the "Virtual 8086 mode"?

This is not the real "real mode" but a virtual real mode on top of protected mode. The real "real mode" still exists native on any x86 CPU and it actually takes a reset cycle to get from protected mode back into real mode =).

If you want to know the details (and got the time), I recommend the programmer's handbook for the 386, which covers everything you need to know about x86 processors.

Linux Torvalds mentions somewhere in the early kernel sources that he read this manual as well besides to Tanenbaum's famous book on operating systems, of course.


Reply Parent Score: 2

Neolander Member since:

No, I don't mean unreal mode ;) I have read the system programming part of the x86 references from Intel and AMD (especially AMD) enough times to know what I'm talking about.

What I think I've read somewhere is that real mode instructions do not use any dedicated hardware execution units anymore on modern x86 processors. That they are fully implemented using microcode and the hardware used by higher-level modes.

Edited 2011-05-20 06:06 UTC

Reply Parent Score: 1