Unlike almost all later consoles, these systems were typically not computers (in which a CPU is running a piece of software), but contained a hardwired game logic.
On these cartridges isn't a program; there are just a few wires that connect electrically a few parts of the intern console hardware that a game appears on the screen.
[1] Devoted to one game or a collection or built-in games, dedicated handhelds tend to employ simple VFD or LCD screens although older models often utilized even more primitive arrays of small light bulbs or LED lights to produce calculator-like alphanumerical screens.
Dedicated handheld systems typically comprise a screen, a number of control buttons, and a compact body that houses the game engine.
Dedicated consoles have appeared for fishing games, where the unit's body itself becomes a specialized controller in the form of a rod and reel.
Konami has also released a line of their classic arcade games, including Frogger, on "plug and play" dedicated systems.
Beginning with the 2001[2] release by Toymax (and later Jakk's Pacific) of the Activision TV Games, there has been a revival of interest in dedicated consoles by nostalgia-driven retrogamers.
Tectoy also released a portable Mega Drive with the firecore firmware, with LCD screen and several games built in, but it has no cartridge port and instead has a SD card slot.