speed, (for experts)
Maybe PingPong is building an adapter to use this Amiga device on MSX ...
only comparing blitter speed with v9938 and v9990 speed.
amiga should be able to copy a 320x200 screen @4bpp almost 110 times x second.
i'm not surprised it was easy to make games for this computer.
it's rougly 2 times faster than v9990 (the v9990 has 8 bit bus however, the amiga 16 bit one)
a conpare with the v9938 looks embarassing.... 
Mmmm... We should now compare that to modern PCs with the latest NVidia/whatever killer video card 
(still using 320x240 resolution of course).
@PingPong: Msx2 digitizing in real time in 255 Colors and Transparency in résolution high résolution 256X212(interleaved)!
0 SCREEN 8,,,,,3
10 COPYSCREEN
20 GOTO 10
You can see easely the transparency in the moments of the colors are in border of Black background 
See this vidéo (real hardware 8280): (Audio stéréo is the digitizing with two Music Modules)
https://www.youtube.com/watch?v=8yimCUW0Dw0
The Colorbus is copied to the Vram at incredible speed :hannibal:
If you have any doubt about the validity of the full digitization in the video below, I scroller VRAM from page 1 to page 0!
Which proves that during scanning, the [Color Bus] VDP 9938 and / or 9958 transfer its status in the VRAM
https://www.youtube.com/watch?v=mSQiA43x3qc
it's rougly 2 times faster than v9990 (the v9990 has 8 bit bus however, the amiga 16 bit one)
but one cant just count databus pins. burst, doublebanking, things can be a factor 4 off from databus pin counting.
further the 9990 is not 8bit but a 128 pins monster with dualported RAMs.
4 vram chips 256kx4bit. makes 16bit of databus.
and dual ported means one got twice of that? then one got 32 bits.
120 nanoseconds
this makes makes a 33 megs per second ballpark. without bursting.
page 2 in the manual,"capable of direct acess from cpu to vram by means of the 16bit bus".
this whole thing smells like 486 vesa local bus and make DOOM with ARM
if the second port of the dual ported RAMs is always available for cpu, and if it is also available for port IO,
then the vram write of port IO could be 7 megs per second.
an 8bit acess to one port of the dualported 120 ns RAMs.
that fills a 256x192 screen of 32768 colors in 60 fps!
well, just speculation, the TurboR touches it at 0.5 megs per second, a magnitude lower.
it's rougly 2 times faster than v9990 (the v9990 has 8 bit bus however, the amiga 16 bit one)
but one cant just count databus pins. burst, doublebanking, things can be a factor 4 off from databus pin counting.
further the 9990 is not 8bit but a 128 pins monster with dualported RAMs.
4 vram chips 256kx4bit. makes 16bit of databus.
and dual ported means one got twice of that? then one got 32 bits.
120 nanoseconds
this makes makes a 33 megs per second ballpark. without bursting.
page 2 in the manual,"capable of direct acess from cpu to vram by means of the 16bit bus".
this whole thing smells like 486 vesa local bus and make DOOM with ARM
if the second port of the dual ported RAMs is always available for cpu, and if it is also available for port IO,
then the vram write of port IO could be 7 megs per second.
an 8bit acess to one port of the dualported 120 ns RAMs.
that fills a 256x192 screen of 32768 colors in 60 fps!
well, just speculation, the TurboR touches it at 0.5 megs per second, a magnitude lower.
i didn't know of the 16 bit databus, always sure of 8 bit width.
Well, about the direct vram access is obscure to me how cpu/vdp will synchronize in a situation like command in progress + cpu access. v99x8 handles this gracefully because it's the 'bus master' ;-)