So how it runs inside a VDM?
I was able to verify it runs in dosbox 0.74 for Windows. I haven't been able to figure out how to get it to use larger than an 80x25 text screen in dosbox, however, so it's limited. VESA reports no extended 132xYY text modes, so it may not be possible. The things I've been designing have been for my personal use and use 132x60 video modes. I'm working on posting some screen shots right now.
DOSbox is a special case. It doesn't offer accurate emulation of an IBM PC compatible architecture. Fortunately even under Microsoft's OS/2 derived products there is a broader choice of emulation methods. Virtual PC or Virtual Server can do the trick for a limited set of modes. VirtualBox or QEMU use the Bochs Video BIOS. And PCem https://pcem-emulator.co.uk/status.html offers support for different graphic adapters.
I typically use VirtualBox and Bochs, but I haven't setup an IBM PC DOS 7 machine yet. But I'm sure it will work because I only use the absolute smallest set of BIOS functions, the rest is all reliant only upon the hardware itself, and should work on any compliant CPU.
ES/1 in production will probably only be an 80x25 video system like normal consoles, and I'll probably allow 80x50, and other modes via VESA calls which can enumerate their capabilities (the 3dfx Voodoo3 2000, for example, enumerates 132x25, 132x43, 132x50, and 132x60 as text modes).
And, it will be open source so people can port it to whatever they like. If the patch is good code, I'll accept it back upstream into the ES/1 mainline. :-)
I almost have the screen shot converter written. I am capturing text with attributes to a disk file, and then running it through a post-processor to generate the .BMP file, which will be converted to a .PNG file. Eventually I'll incorporate this ability in the text-based console using the iVio_screenCapture(filename); function.