Retro Consoles Wiki

The Entertainment Computer System (ECS) add-on module essentially added three features to the Intellivision: an additional 2K of RAM, a second sound chip and the option of plugging in a computer keyboard, a music keyboard or an additional two hand controllers.


This add-on essentially adds five components to the Intellivision:

  • ECS EXEC/BASIC ROM, containing the built-in BASIC programming language and additional BIOS routines to handle the added hardware features
  • additional 2K of system RAM (supposedly, the system could be further expanded to as much as 64K with add-on memory modules, but no such modules ever made it to production)
  • additional AY-3-8910 sound chip (this was the same sound chip used in the Intellivision)
  • a cassette recorder/printer interface (used the same peripherals as the Mattel Aquarius)
  • two additional input ports for the alphanumeric Computer Keyboard, the Music Synthesizer keyboard, or two additional Intellivision Game Controllers.

The ECS EXEC has routines to decode the key presses from any of these devices for use by the game programs. Note that functionally, the Music Synthesizer is just a keyboard; the "synthesizing" takes place in the Master Component and Computer Adaptor using their two sound chips under the ECS EXEC's control.


The sound chip is a GI AY-3-8914, the same as in the Master Component. The chip contains three separate channels of sound, each channel of which can be individually controlled for frequency and volume. There is also a noise generator on the chip, which can be added to any of the three channels. These three channels are mixed with the three in the Master Component and fed to the sound output of the TV. Musically, this means six notes can be played simultaneously.


The 12K ECS EXEC/BASIC ROM chip contains three types of information:

  • Additional EXEC routines that the game program can call on for functions such as decoding the keyboards, reading or writing data to tape, playing music, or printing.
  • The ECS BASIC programming language. This is a sub-subset of BASIC, with many idiosyncrasies and limitations. The different elements of a program (commands, variables, constants) are color-coded. Special commands in ECS BASIC can read the locations in plugged-in game cartridges where moving-object (sprite) graphics are (usually) defined. Nicknamed the "sucky" feature, this allows the consumer to pull moving objects from a cartridge and use them on screen with his or her own BASIC program.
  • Graphics of musical notes to be used with the music keyboard and cartridges.

The default on reset for the ECS is to display a menu selection of game, BASIC, or music. However, the game designer can program his or her cartridge to bypass the ECS menu and go directly to the cartridge's title screen. Even if the menu screen is bypassed, the ECS features are available to the programmer. [No policy on this was defined; it was left to the individual programmer on whether or not to bypass the menu. Pre-ECS Intellivision game cartridges all allow the menu to be displayed; the ECS games Mind Strike and Scooby-Doo's Maze Chase, for example, bypass it.]


An additional 2K of 8-bit RAM is contained in the ECS. How much of it is available for use by the game program depends on how many of the ECS EXEC/BASIC routines are used. If the game does not use any of the ECS EXEC routines or BASIC, 1,984 RAM locations are available to the program. If all features are used, including BASIC which reserves a 1,535 location block for programming, only 2 locations of the system RAM are left over.

Note: Use of the ECS/BASIC features also eats up some of the Master Component's 147 8-bit scratchpad RAM locations normally available to the programmer; from 3 to 14 locations, depending on the features used.


The Computer Adaptor contains a UART (Universal Asynchronous Receive/Transmit) allowing data to be moved serially to or from a cassette recorder or to be printed under program control.

[The ECS was designed to work with standard audiocassette recorders, and in fact came with a list of current models that it was compatible with, and the same 40-column thermal printer sold both for the original Keyboard Component and the Aquarius system. At the June 1983 CES, the ECS was shown with Aquarius Data Recorders and Printers affixed with "Intellivision" nameplates; they were never actually released with those labels.]


The Computer Adaptor has two input ports (as in the Intellivision, these ports are physically the input ports of the Adaptor's sound chip). These ports can be used for:

  • The Computer Keyboard, which uses both ports
  • Two additional Hand Controllers so that four-player games are possible
  • The Music Synthesizer, which also uses both ports.

Optional add-ons[]


Sprinter40 Thermal Printer add-on

*Music Synthesizer 49-key music keyboard

  • extra Intellivision game controllers (for 4-player games)
  • data cassette drive
  • 40-column thermal printer