Hello again.

I want to update my progress, maybe it's can be useful for someone.
Yes, it's all about es register. Solution is to place a character table in 0000:FFFF addresses. Now I see my own characters on the screen.
It's may be tricky way, because I can't allocate memory and write via address without allocation, but table can be overwritten when interrupt is done.

If anyone knows much clever way - you're welcome, this is very interesting information for me.

Konstantin Novikov 

ср, 10 июл. 2019 г., 11:53 Konstantin Novikov <novikov.konstantin.nk@gmail.com>:
Hello, dear SeaBIOS community. I need your help. 

I want to change character set with my own character table. Now I'm trying to use Int 10h, function 11h. As SeaBIOS works with mode #3 by default (text mode, 80x25 cells), I'm calling subservice 0h for set my table with 8x16 characters.

But It' doesn't work. Characters are changed, but symbol's form isn't depends on what's my table contains. I think, It happens because I need to set table pointer in registers es and bp. In flat model I can't get value of segment, which contains my table.

I tried to write 0 in es register and allocate memory in low zone - didn't changed anything.

So, can you help me? Maybe, I just using wrong way, and solution is much easier?

Thank you for attention. 
Novikov Konstantin