Almost MSX or Beyond MSX?

Actually already mentioned in 2019 by Piter Punk:

"Long time without any news about hidden MSX computers. But even at the underground the quest continues.

This video shows another hidden MSX2 computer booting the Gradiente MSX BIOS. We show this machine at MSX Jaú 2018. We used an MSX1 BIOS instead an MSX2 because the need of an additional slot for SUBROM is troublesome to do the initial tests.

Video showing Gakken GCX Study Computer (audio in portuguese)

Gakken's machine were a bit different than the other hidden MSX's mainly because they have a lot of different models:

GCX-1000 - rear proprietary slot, MSX cartridge slot, two joystick ports, integrated cassette
GCX-1100 - rear proprietary slot, MSX cartridge slot, one joystick port, card reader, integrated cassette
GCX-VN - rear proprietary slot, internal BIOS, one joystick port, card reader, integrated cassette
GCX-VCD - rear proprietary slot, proprietary BIOS, one joystick port, card reader, integrated CD-ROM
And even their own line of accessories, like card-readers, PCM modules, CD-ROM controllers, etc.

In the video, I claim that probably the keyboard is accessed in a non-MSX way, that is why we can't type anything after the BIOS boot. I was plain wrong, the real reason is that the Gakken GCX machines uses Z80-CTC to control interrupts, as the MSX's interrupt handler didn't clears the interrupts (using RETI instead of RET) the machine get stuck when interrupts are enabled.

I had hopes to take a lot of pictures, make a blog post, cartridge dumps, etc, before announce this machines. But the spare time is short and I guess that little information is better than no information.

If you have any doubt about this machines and I could help, I'll be very happy to answer."

Besides the 4 versions mentioned above, there is also the GCX-V.