Subj : Re: CPU Hog
To   : Ryan Fantus
From : Tony Langdon
Date : Tue Aug 09 2022 19:58:00

-=> On 08-09-22 00:30, Ryan Fantus wrote to fusion <=-

 fu> another neat thing is each ntvdm gets it's own "640k" of ram, it's own
 fu> EMS/XMS, etc.. it's really the scaffolding of the single-pc multinode
 fu> bbs.

 RF> Wow, I had no idea. That's pretty neat. Honestly, I use Windows 7 32
 RF> bit for my doorgame host and it works astonishingly well. No slowdowns
 RF> or any other apparent issues. Only some games like Yankee Trader don't
 RF> work; everything else seems to hum along as expected.

That's the magic of virtual 8086 mode.  Same happened with DESQview on a 386,
every session got its own 60k (less any OS/TSR overhead loaded before DV).  And
OS/2 really made good use of virtual 8086 mode with its DOS subsystem - the
"better DOS than DOS".

 fu> it's neat stuff. bit of a shame the 16bit mode is not accessable from
 fu> 64bit oses.. but we're lucky it works in 32bit mode. in theory it should
 fu> be faster than the ntvdm64 one, but with modern cpus i don't know if you
 fu> could measure that difference anymore

As I said in another message, I'm sure I read it's possible to spin up a DOS VM
in 64 bit mode, by using the hardware virtualisation capabilities of modern
AMD64 CPUs, which would result in similar functionality.


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