I also tested the completed computer on an Olivetti monitor (that I own), and also a different PS/2 keyboard. Results were equally satisfying.
I have to say I enjoy using the "Terminal-BASIC" programming language (by Andrey Skvortsov) which is the initial reason I put together the whole project of the "BASIC Computer"; it's user-friendly and quite versatile in its features.

The Terminal-BASIC startup message greets you when you boot up the machine:

The total hardware of this computer is really minimal: just 3 boards. The only board that needs to be assembled is the "Computer Terminal Board" (lower one of the three). The other two are out-of-the-shelf parts: microSD-Card module and Arduino MEGA2560 .

More details on programming the chips for the "Computer Terminal Board" and assembling the board later. For now,  just take a look at the pictures and feel some magic of the 80's !  :-)