Though what people generally think, the Emerson Arcadia 2001, is only a licensed system like many other ones software-compatible with it. But the Arcadia 2001 is certainly the most known one of these systems, explaining why this console group has often been called "Emerson Arcadia 2001 clones".
Though it was the most popular system of this console group, it was not necessarily at the origin of it. Things must be seen differently. Philips / Signetics developped a hardware platform to demonstrate the possibilities of their Signetics 2650 & 2636 chipsets. Somehow, this hardware was licenced (by Philips) to many third-companies around the world resulting in systems like the Interton VC-4000, Voltmace DataBase, Acetronic MPU-1000, ITMC MPT-05, etc.
Some times later, the hardware was improved, with the use of a Signetics 2637 instead of the 2636 (handling the audio & video), somehow resulting in a new wave of licenced systems, all based on the same hardware and playing the same games. This console group includes : the Ormatu Spelcomputer 2001, Advision Home-Arcade, Prestige MPT-03, Tele-Fever, etc. and the Arcadia 2001.
All these systems (based on the 2650 & 2637 chipsets) are "software-compatible" with each others. It means that they all could play each other games if their cartridge slots were identical (which is not the case, resulting in sub-groups).
The Arcadia 2001 sub-group includes : Advision Home Arcade (France), Bandai Arcadia (Japan), GiG Electronics Leonardo (Italy), Hanimex HMG-2650, Leisure-Dynamics Leisure-Vision, Intercord XL 2000 system, Eduscho / Tchibo Tele-Fever, etc... It means that all these systems can directly use the same cartridges.
The Software library is not very impressive, but there are good reasons for that. First, some titles ar almost just direct ports from "Interton VC-4000 & compatible systems" group. Philips (remember, at the origin of this ystem) also had great plans for his new hardware platform. It released adaptations of famous Arcade classics (Pac-Man, Berzerk, Phoenix, etc.) but Atari sue them. Philips was then forced to deeply modify those games, resulting in poor adaptations... at least for the Arcadia 2001. Because, outside US, other compatible systems sometimes had un-modified version in their library (Robot Killer for the MPT-03, for example).
The Arcadia is equiped with two detachable controllers made of a screwable joystick, a 12-buttons keypad (flat membrane buttons) and 2 fire buttons (they in fact have both the same function). Small plastic layers were delivered with each game, explaining the different key functions when placed over the keypads (like with the Mattel Intellisivision).
The Control panel is made of 4 buttons (Start, Clear, Select A and Select B) and the power on/off button.