This is an initiation computer. It was sold as an add-on for the Japanese Famicom (but can't be connected to a NES as it lacks the Famicom's Expantion Port).
In fact the system is composed of three parts : the Famicom, the keyboard and the Basic cartidge.
The keyboard is connected to the expansion port situated at the front of the Famicom. Then a Basic cartridge must be inserted into the Famicom catridge slot. As the keyboard is almost "empty", most of the Famicom's hardware is used, along with the Basic cartridge RAM chips.
The Basic delivered with the keyboard is the NS-HUBASIC, where "N" stands for Nintendo, "S" for Sharp and "HU" for Hudson, as they all contributed to this project.
Once inserted there is only 1982 bytes free to play with ! But it was possible to back-up the program into the cartridge itself by powering it with 3 battery cells. This saving method wasn't reliable as quite often the programs were lost because of bad contacts...
Hopefully, a tape-recorder was available, but there again, the adjustment of the input level was quite difficult to get.
Some games using the built-in save/load feature of the Basic cartridge were released such as "Lode Runner" (edit mode) and "Challenge Race".
The catalog number of the keyboard is HVC-007.
Family Computer Keyboard
BUILT IN LANGUAGE
NS-HUBASIC V1.0, V2.0A, V2.1 or V3.0
Full-stroke keyboard with functions keys and arrow keys