Text encoding Babel. Was Re: George Keremedjiev

[Maciej W. Rozycki]

On Tue, 4 Dec 2018, Liam Proven wrote:

> >  I don't know if the unreal mode has been retained in the x86 architecture
> > to this day; as I noted above it was not officially supported.  But then
> > some originally undocumented x86 features, such as the second byte of AAD
> > and AAM instructions actually being an immediate argument that could have
> > a value different from 10, have become standardised at one point.
> 
> I know, and was surprised that, v86 mode isn't supported in x86-64.

 In the native long mode, that is.  If you run the CPU 32-bit, then VM86 
works.  I guess AMD didn't want to burden the architecture in case pure 
64-bit parts were made in the future.

> This caused major problems for the developers of DOSEMU.

 And also for expansion-BIOS emulation, especially with graphics adapters 
(which, accompanied by scarce to inexistent hardware documentation, made 
mode switching even trickier in Linux than it already was).  It looks like 
fully-software machine code interpretation like with QEMU is the only way 
remaining for x86-64.

  Maciej