Now almost completed.

I had encountered one mysterious situation. I made two similar tiny computer both are based on ATMega1284, but one with microSD and the other is full size SD card. The previous demonstration was taken by microSD card version (without RTC nor Kanji ROM), because it did not work well with color OLED...!

This is the microSD version. Surely working but it is not uncomfortable not knowing why the other one with color OLED does not work!

Indeed, the other one is perfectly working with SSD1306 Monochrome OLED. This was a hint and new good to know. Actually reset signal (RST) of SSD1306 and SSD1331&1351 have different behaviour. RST of SSD1306 can be simply pull-up during operation and SSD1331&1351 should have RST signal generated by MCU. My SDcard version has pulled-up RST signal and this was the reason.

So I change wiring of RST from pull-up to MCU pin, and now it is surely working well. Actual operation can be found in the following movie... have fun!