On 27/01/2025 6:25 pm, Ben Russell via Freedos-devel wrote:
I have some corrections for some obscure things...
:-)
You absolutely can still run 16-bit protected-mode code in 64-bit long mode
Oh, yes indeed. I see I was unclear. My understanding, possibly incorrect, was that once you are in 64-bit mode, you can't set the CPU into 16-bit protected mode.
But 16-bit code still works. Intel did propose removing it and I wrote about it:
https://www.theregister.com/2023/05/25/intel_proposes_dropping_16_bit_mode/ However I believe that proposal has been formally dropped now.
Microsoft has an explanation somewhere of why 16-bit programs don't run under 64-bit Windows, claiming that it's because some of the handles are wider and don't fit in the API.
Really? I thought it was as simple as it removing the NTVDM tool (NT Virtual DOS Machine).
It's been reconstructed from leaked sources and you can reinstall it. I wrote about that, too.
https://www.theregister.com/2022/06/28/friday_foss_fest_running_dos/
Yes the upper bound of virtual memory is... 1 GB before tax (you lose 2 descriptors because one is unusable and you also need a descriptor for the LDT as far as I know).
OK.
I'm guessing the 16GB is a typo
It was, yes. Mea culpa. -- Liam Proven - Profile: https://about.me/liamproven Email: lpro...@cix.co.uk - Google Mail/Hangouts/Plus: lpro...@gmail.com Twitter/Facebook/Flickr: lproven - Skype/LinkedIn: liamproven IoM: +44 7624 227612 ~ UK: +44 7939-087884 ČR (+ WhatsApp/Telegram/Signal): +420 702 829 053 _______________________________________________ Freedos-devel mailing list Freedos-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-devel
