last month I got a Commodore 16 and bought a Toshiba HC10 (MSX) system.
The Commodore 16 has the same basic architecture like the Plus 4, but misses the 3-1 function ROM, user port and (6551) ACIA serial port chip.
It also has 16Kb of RAM instead of the 64Kb that the Plus 4 has.
The circuit difference of the RAM is only minor and can be quickly modified by supplying the A14 and A15 lines to the multiplexer and changing the RAM chips.
So this will be my first mod (keep you posted).
The Toshiba HC10 I bought is a MSX system. I bought it with two game cartridges and a Philips floppy drive controller cartridge.
Also a (DIY) external drive and monitor was supplied.
I bought it to play a little with the “different technique” MSX is using.
I will probably sell the system when I’m done playing.