Intellivision | Code Like It's 198x

“Atari vs. Intellivision? Nothing I could say would be more persuasive than what your own two eyes will tell you. But I can’t resist telling you more.” The writer George Plimpton signed that line under an advertisement in the first issue of Electronic Games, dated Winter 1981. Beside it Mattel printed pairs of screens: Atari’s baseball and Intellivision’s, Atari’s soccer and Intellivision’s. “They’ve got arms and legs like real players do,” the text pointed out.

The Intellivision took on the Atari 2600 by inviting buyers to compare the two, and it sold in millions. It was a very different machine to program. A 16-bit processor ran the game while a separate display chip drew the screen, and players steered with a 16-direction disc and a keypad that divided opinion. Mattel promised to turn it into a home computer and struggled to do so for four years. Mattel Electronics lost heavily in the 1983 crash and closed in January 1984, but the Intellivision was still on sale six years later.

Fast facts

Maker: Mattel Electronics, a division of the toy company Mattel. Sears sold it as the Super Video Arcade.
Launched: test market in Fresno, California, 1979; across the United States from 1980, at $299 list.
CPU: General Instrument CP1610, a 16-bit processor with eight 16-bit registers, run from the 3.58 MHz colour clock.
Memory: the service manual lists “7K internal ROM, RAM, and I/O structures”. Game cartridges plug into the rest of the 64K address space.
Video: the Standard Television Interface Chip (STIC, General Instrument AY-3-8900): a background of 20×12 character cards of 8×8 pixels, eight moving objects, 16 colours.
Sound: a General Instrument programmable sound generator with three channels; the Intellivision II’s parts list names an AY-3-8914.
Controllers: a 16-position disc, a 12-key keypad with printed overlays and four side buttons, wired to the console.
Sales: later estimates put total sales at between about 3.5 and 3.75 million.

Mattel’s answer to the 2600

Mattel already sold handheld electronic games when it began work on a console in 1978. According to Video Games in December 1982, Mattel unveiled the $299 Intellivision Master Component at the Consumer Electronics Show in January 1980. It was expensive, and analysts wondered whether a games-only machine could compete with the new home computers. Nobody questioned the pictures. The magazine recalled Newsweek trying the cartridges and asking, “But can this thing walk the dog?”

The price came down quickly. Mail-order advertisements in 80 Micro offered it at $299 in May 1980 and $229 by the end of that year. In October 1982 Video Games still called the Intellivision and the Bally Astrocade “the Lincoln and Cadillac of TV-game systems”, with the Intellivision selling for between $250 and $300, and a $59 add-on, the Intellivoice, gave some games speech.

Mattel’s service manual describes a system “based on two processors which time-share a bidirectional bus”. One is the General Instrument CP1610, a 16-bit microprocessor that “computes the game action against the stored program rules”. General Instrument’s manual for the CP1600 family gives it eight 16-bit registers. The other is the Standard Television Interface Chip, or STIC, which “interprets a condensed memory area and uses this to generate a color video signal”.

That division shaped every Intellivision game. The STIC provides “eight coordinate-positioned ‘foreground’ objects” (moving objects, or sprites) and a background built from character patterns, whose codes the program keeps in a table in RAM, one for each position on the screen. Joe Zbiciak’s documentation for the jzIntv emulator gives the details programmers later worked from: the background is a grid of 20 by 12 cards, each 8×8 pixels, drawn either from the 256 built-in patterns in the graphics ROM or from 64 that the program defines in graphics RAM. The moving objects can be magnified, mirrored and drawn at twice the vertical resolution of the background, and the STIC reports collisions between them, the background and the screen edge. Of the 16 colours, eight can be used freely and the other eight only in some modes.

The program tells the STIC what to draw and the STIC draws it, a contrast with the Atari 2600, whose programs build the picture line by line. Carol Shaw, who wrote River Raid for Activision, explained the difference to Electronic Fun in 1983: “Intellivision gives you a high resolution background that’s pretty easy to program but it doesn’t give you the flexibility to go in and do anything else.” On the 2600, “every line in your program is deciding what to display”, she said, while the Intellivision goes and does what it is told, “and you can’t go in and change something in the middle of the screen as easily.”

Memory was tight and oddly shaped. The jzIntv memory map shows 240 bytes of 8-bit scratch RAM and 352 words of 16-bit RAM, 240 of which hold the background table for the screen. Most game ROMs were only 10 bits wide, so a 16-bit constant had to be stored as two bytes and read with a special prefix instruction. Games could also call routines in the “executive” ROM built into the console, which the service manual describes as holding “program data common to all external programs”.

Sound came from a General Instrument programmable sound generator, whose two 8-bit input/output ports also read the hand controllers, “for user interface via the hand controllers”, in the service manual’s words. The Intellivision II’s parts list names the chip as an AY-3-8914, a separate part number from the AY-3-8910, though the jzIntv memory map shows the same kinds of register: a 12-bit period for each of three tone channels, a noise period, a 16-bit envelope period and an envelope shape. General Instrument’s own AY-3-8910 data sheet suggested driving its sound chips from the CP1610.

The disc and the keypad

Each controller had a flat disc that could be pressed in 16 directions, twice as many as a joystick, four side buttons and a 12-key keypad. Every game came with plastic overlays that slid over the keypad and labelled the keys, and sports and strategy games had players tap in codes and commands. Players were divided. Reviewing the Intellivision II in April 1983, Electronic Fun wrote that the “infamous disc controller” required “the nerves of a diamond cutter and the hands of a brain surgeon”, and that first-time players could spend more time looking at the keypad than at the screen.

Plimpton and the Blue Sky Rangers

Mattel sold the Intellivision on comparison. The Plimpton advertisements set its sports games beside Atari’s, and the rivalry spilled into fan clubs. In its first issue, dated Winter 1981, Electronic Games reported that Atari had started a club with a newsletter, Atari Age, and that Mattel had answered with an Intellivision Game Club, “with George Plimpton as honorary president”.

The games were written in-house. Mattel’s programmers were kept anonymous so that Atari could not hire them away, and according to later accounts it was a TV Guide article in June 1982 that named them the Blue Sky Rangers, after the “blue sky” meetings where they brainstormed game ideas. By 1983 Mattel also sold 2600 versions of its games under the M Network label. Other publishers followed: Coleco made Intellivision versions of its arcade conversions, and Activision brought out Pitfall! for the Intellivision in late 1982. In December 1982, Video Games reported, Atari took Imagic to court over the Intellivision version of Demon Attack, which it said copied the mothership from Phoenix.

The computer that never came

Mattel’s advertising promised that the Intellivision would become a home computer, with a Keyboard Component. It went on sale only in small numbers, in a few test markets. The Intellivision Lives history, written by former Mattel programmers, says about 4,000 were made. Complaints from buyers who had been promised a computer led the Federal Trade Commission to investigate Mattel. Mattel cancelled the Keyboard Component and offered to buy back the keyboards already sold.

Its replacement was the Entertainment Computer System, a much cheaper add-on built by a separate team. Electronic Fun described the Computer Adaptor in April 1983: 2K of extra RAM, 12K of ROM with BASIC built in, a second sound generator that raised the channels to six, and a keyboard. Video Games Player greeted it that November: “George Plimpton promised that we would someday be able to turn our Intellivisions into computers. Finally, that day has come.”

Intellivision II and the end of Mattel Electronics

In 1983 Mattel replaced the woodgrain console with the Intellivision II, smaller, lighter-coloured and cheaper. Electronic Fun found that “electronically, the set remains unchanged”, with the same processor, but with detachable controllers, a power light and a single on/off/reset button. By November Video Games Player reported it selling for as little as $99, and less after rebates, “even lower than the Atari VCS”. A System Changer let it play Atari 2600 cartridges.

It was not enough. The market collapsed during 1983, and Mattel lost $156.1 million in the second quarter alone, as the 1983 crash entry reports. In January 1984 Mattel closed its electronics division. That November a reader told Electronic Games he had been “greatly distressed to hear that Mattel was leaving the electronic games field”, and asked whether the investors who had bought the business would make new games. The magazine’s Game Doctor thought the Intellivision “a dead issue, barring a rise from the grave”.

INTV and after

It rose anyway. INTV Corporation, the company formed by those investors under Terrence Valeski, sold off Mattel’s stock of consoles and games and in 1985 brought out its own version of the console, the INTV System III. Public sources report that it hired former Mattel programmers to finish games Mattel had left incomplete, and that it stopped selling the Intellivision in 1990.

The Blue Sky Rangers kept the machine alive. In 1997 two of them, Keith Robinson and Stephen Roney, formed Intellivision Productions and acquired the rights to the Intellivision and its games, which they reissued for home computers on the Intellivision Lives CD. In 2018 the musician Tommy Tallarico took over the brand as Intellivision Entertainment and announced a new console, the Amico, which did not reach the shops. In May 2024 Atari bought the Intellivision brand and its library of games.

Sources

Mattel Electronics, Intellivision II Service Manual (1982): specifications (the CP-1610, “7K internal ROM, RAM, and I/O structures”, three sound channels, 16 colours, 192 by 160 picture elements); theory of operation (two processors sharing a bus, the STIC’s foreground objects and background mode, graphics ROM and RAM, the executive ROM, the 7.159090 MHz crystal and 3.579545 MHz clock, the sound generator’s I/O ports and the hand controllers); parts list (CP1610, AY-3-8900-1, RO-3-9503, AY-3-8914).
General Instrument, AY-3-8910/8912/8913 Programmable Sound Generator data sheet: the suggestion to drive the chip from “the General Instrument 16-bit CP1610”.
General Instrument, CP-1600 Microprocessor Users Manual (1975): eight 16-bit registers.
Joe Zbiciak, jzIntv emulator documentation, “STIC (AY-3-8900) Reference”, “Intellivision Memory Map” and “Introduction to CP-1600 programming” (community reference): the 20×12 background cards, 256 GROM and 64 GRAM cards, moving objects, their attributes and collision detection, the PSG registers, the colour sets, scratch and system RAM, 10-bit ROMs and double-byte data.
Sears, Super Video Arcade owner’s manual: the Sears version of the console.
80 Micro, May 1980 and December 1980: mail-order prices of $299 and $229.
Electronic Games vol. 1 no. 1, Winter 1981: Mattel’s Intellivision advertisement signed by George Plimpton; “Hotline” news of the Atari and Intellivision game clubs.
Video Games vol. 1 no. 2, October 1982, p. 64: Astrocade and Intellivision as “the Lincoln and Cadillac”, prices, the $59 Intellivoice.
Video Games vol. 1 no. 3, December 1982, p. 69: the $299 list price, the January 1980 CES and Newsweek’s “walk the dog”.
Video Games vol. 1 no. 6, March 1983, p. 80, “Atari v. Coleco & Imagic”: Atari’s suit over the Intellivision version of Demon Attack.
Electronic Fun with Computers & Games vol. 1 no. 6, April 1983: letters page, the Computer Adaptor (2K RAM, 12K ROM, BASIC, six sound channels); Michael Blanchet’s review of the Intellivision II, pp. 91–92 (the diamond cutter and the brain surgeon).
Electronic Fun with Computers & Games vol. 1 no. 10, September 1983, interview with Carol Shaw: the Intellivision and the 2600 compared.
Video Games Player vol. 2 no. 2, November 1983, pp. 20–21, “Mattel Strikes Back”: the Intellivision II at $99, the System Changer, M Network, the Entertainment Computer System and Plimpton’s promise.
Electronic Games vol. 2 no. 16, November 1984, p. 84, “Ask the Game Doctor”: Mattel leaving the field, the investors, “a dead issue”.
Videogames Hardware Handbook vol. 1, 2nd edition (Imagine Publishing, 2016), pp. 28–31, “Intellivision”: Mattel’s handheld games and the start of work in 1978, the 1979 test market, INTV and the System III, the former programmers obtaining the rights, total sales of about 3.5 million.
Intellivision Lives, “Keyboard Component” (history by former Mattel programmers, web, secondary): about 4,000 made, the FTC investigation, the Entertainment Computer System and the buy-back offer. https://history.blueskyrangers.com/hardware/keyboardcomponent.html
Wikipedia, “Intellivision” (web, secondary): the Fresno test market, the Keyboard Component’s test markets and the FTC, the closure of Mattel Electronics, INTV and Terrence Valeski, the end of sales in 1990, Intellivision Productions in 1997, Intellivision Entertainment in 2018 and Atari’s purchase in May 2024, and sales of more than 3.75 million. https://en.wikipedia.org/wiki/Intellivision
ClassicGamer Magazine vol. 1 no. 1, Fall 1999: the Blue Sky Rangers’ website and the Intellivision Lives CD.
Wikipedia, “Blue Sky Rangers” (web, secondary): the programmers’ anonymity and the TV Guide article of June 1982. https://en.wikipedia.org/wiki/Blue_Sky_Rangers