This japanese computer seems quite powerful. The main board is located into the main case, under the monitor.
Inside this main case there are 6 expansion slots which is quite enough ! Thus a lot of expansion boards were available (disk, printers, 8088, Z80 boards, etc).
An interesting feature is that there's a little trap-door on the keyboard which reveals some cool control switches : a power switch, a text mode switch (80 / 40 columns), a reset button and volume control knob. Quite useful !
I designed a number of add-on cards for this computer in my teenage years - two floppy disk controllers, hard disk interface with networking, multifunction card with rtc, two ay-3-8910 psg chips and a spo256 speech chip along with two atari joystick ports and a z80 card to run cp/m. I still have those boards but not the computer. It was a very well made piece of hardware and very reliable - too expensive for me to buy at the time.
Thursday 26th May 2016
MB-6890 / Basic Master Level 3
BUILT IN LANGUAGE
Hitachi Level-3 Basic Version 1.0 (Copyright Microsoft)
QWERTY full-stroke keyboard, separated numeric keypad, 5 function keys
24k (Basic Interpreter)
80 x 28 / 40 x 25
80 x 100 / 160 x 100 / 160 x 200 / 320 x 200 / 640 x 200
6 expansion slots, RS232c, Tape-recorder
Tape-recorder, printer interface board, light-pen, Chinese character ROM board, 8088 CPU board, Disk Interface board, Z80 CPU board, RAM expansion boards