* C compilers that can target 16 bit x86 usually have support for "far pointers", which are 32 bit wide pointers consisting of both a 16 bit segment and a 16 bit offset. You should be able to use that instead of your assembly wrappers. This allows you to directly access screen memory in C, i.e. letting the compiler do the job of setting up the segment registers, which also has the great benefit of not having to push, write, and pop ES for every byte (if you copy a block into screen memory for example, the compiler only needs to set up the destination register once).

* The IVT is correspondingly also a list of FAR pointers. It's a common 16 bit x86 concept. The CPU knows about them, they are also more generally used for far jumps and far calls.

* As others have said, just pick one of the many, many available text mode font ROMs.

* I'm curious how compatible that AMD Elan is to actual PCs. Probably a lot, since by that time PCs were kind of the x86 standard, though not necessarily. The earlier 80186 with its integrated peripherals (interrupt controller etc.) was very incompatible, for example. Shouldn't impede your project, just dictates how easily you can run DOS programs overall.

I found this part of the process unusual:

In total my final font-header-file is about 22kB but it was a great relief to use AI for this dumb task. Google Gemini produced a nice font for my BIOS. On individual characters I had to fix some pixel-errors

Instead of simply searching for one of the numerous font-dumps that exist on the Internet, which will already be 100% correct for all of CP437? The CGA font would be a good match (and the one he ended up using looks like it), but there are plenty of other 8x8 fonts available.

More background information: the Behringer brand has always very intentionally targeted the budget-conscious customer. One way they have achieved their low price targets has been to straight-up clone competitors’ products, building them with cheaper components and cheaper labor.

But they also do their own R&D, both within, erm, “familiar” physical form factors and in totally novel designs. I have no idea if this product is specifically inspired by any other studio-in-a-box, but my gut reaction is that no other competitor in this space would have sourced a damn 386-compatible CPU for such a product line in 2002.

My guess is Behringer got a great deal on some second-source manufacturer’s last stock of 386s (maybe in bankruptcy?), and only that kind of deal would have enabled Behringer to enter this market.

If anyone has a more informed take, I would love to waste time reading about the history of this thing!

* Supposedly 2007 but that does not sound right for embedded customers unless Intel built a lifetime supply.