QB doesn't support SCREEN 5/6 even on real hardware. You need to use Tandy GW-BASIC (or EGA modes).

If you are trying to run existing code, you may be interested in the PC-BASIC emulator.

Thanks a lot for advice! As far as know, Tandy and EGA modes are not compatible. Is it possible to emulate the SCREEN 7 mode 320 × 200 × 16 in Tandy (PCJr)?

I'm not sure about EGA emulation on an actual Tandy. I just mentioned EGA for DOSBox purposes.

I did find the GRAFIX library which is similar to what you originally wanted. It's not integrated with QB like MSHERC/Hercules support (you need to use the library functions instead of QB's native commands). But it's probably more fun than GW-BASIC.

Thanks again.
Can't run SCREEN 13 mode on QBasic despite running TCR — Re: TANDY Dos-Gaming-Thread (1000RL/HD)
Now going to deal with the attached library.

The author did a great job adding Tadny support to Q(uick)Basic. However, as I understand it, new commands have been added to draw graphics, and LINE (PSET, CIRCLE) is no longer working. Accordingly, graphics are not displayed in ordinary BASIC commands.

The modified driver for also did not help to display EGA or VGA (320 × 200 × 16) — https://www.brutman.com/forums/viewtopic.php?t=852

yevrowl wrote on 2022-07-04, 11:52:

The author did a great job adding Tadny support to Q(uick)Basic. However, as I understand it, new commands have been added to draw graphics, and LINE (PSET, CIRCLE) is no longer working. Accordingly, graphics are not displayed in ordinary BASIC commands.

Yes, that's how it works. QB doesn't support Tandy graphics. The internal commands can't be changed with a library. You use the library functions instead.

yevrowl wrote on 2022-07-04, 14:03:

The modified driver for also did not help to display EGA or VGA (320 × 200 × 16) — https://www.brutman.com/forums/viewtopic.php?t=852

Why would it? That mod is for PC Jr machines to use Tandy video.

No matter how much searched, just can't find what's the catch...
Everything works in all graphic modes, but only in Tandy the output of the Forsyth–Edwards notation does not work...