AY-3-8500

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The AY-3-8500 is an integrated circuit by General Instrument Corporation that was manufactured from 1976 onwards. Also called Ball & Paddle by its manufacturer , it is used to output seven different video games, for example on a television set. Five of the individually selectable games are based heavily on Pong in terms of their gameplay, controls and audiovisual presentation . The other two are shooting games that require a light rifle as a controller. For marketing areas with NTSC television standard, General Instrument manufactured its own variant of the chip under the name AY-3-8500-1 .

The circuit contains all assemblies for querying hand controllers, for executing the game mechanics and for generating both sound and image. In contrast to the then much more expensive microprocessors , the AY-3-8500 is not programmable. The game mechanics and the graphic display cannot be changed, only some game parameters can be set. The games are therefore often referred to as hard-wired (English hard-wired ) and the associated console as specialized (English dedicated called).

The AY-3-8500 was mass-produced and offered inexpensively. Smaller or non-specialist companies such as the toy manufacturer Coleco Industries were also able to manufacture their own devices for the prospering video game market in 1976. The circuit was then used in millions of video game consoles, which quickly led to an oversupply. As a result of the associated ruinous price war among manufacturers, the video game market collapsed in the course of 1977, the first video game crash . Then bigger companies like Atari finally switched to the much more flexible microprocessor-controlled video game consoles. In contrast, companies from the Far East in particular continued to produce video game consoles with the AY-3-8500 until around 1983.

history

In 1972, the US introduced the first commercial video games to the entertainment world. The Odyssey from Magnavox and later also other devices for the home area were considerably less powerful than the arcade machines set up in public places like Ataris Pong with their expensive electronic assemblies. In order to be able to supply the apparently lucrative home entertainment market with high-performance and at the same time inexpensive devices, various companies began developing highly integrated electronic circuits. These should combine the machine electronics in a handy component with only low manufacturing costs. The first video game console with such a special component was Atari Home Pong from 1975. However, Atari reserved the sole use of the circuit. Other manufacturers of consumer electronics were initially left out.

development

Presumably as early as 1973 the semiconductor manufacturer General Instrument in Glenrothes, Scotland, evaluated the miniaturization of video game electronics at the time. However, the management saw no potential and rejected any further involvement in this area. Nevertheless, the employed engineers Gilbert Duncan Harrower and Dave Coutts began - in their spare time - to develop the first hand-wired prototype of a corresponding special component. This functional design was convincing in-house and the management of General Instrument decided only a little later to check the economic viability of the project. In 1975, General Instrument officially began developing the chip on behalf of the Finnish television manufacturer Salora Oy. With the well-known companies Telefunken , Loewe-Opta and the Spanish Vanguard SA, further future customers soon followed. At the request of interested parties, General Instrument also integrated games other than the screen tennis originally planned . There were also additional options for greater variety within the individual games.

In the course of 1975, General Instruments transferred the adapted prototype with its 66 component groups into corresponding photo masks in order to be able to produce the highly integrated circuit. Because the company saw great sales potential in non-European markets, the company had previously deployed 15 engineers in Hicksville, USA, to design a variant for the NTSC television standard. After completion of the development work, the production of test samples started in January 1976. The first demonstration models of the chip with its various Pong variants and light rifle shooting games were available in February. In order to be able to produce the chip in large quantities, General Instrument has now converted its own factories that had previously produced components for pocket calculators. In addition, suitable wiring electronics were provided for the sound and image generation for the chip now called AY-3-8500 Ball & Paddle . This made it easier to use, which in turn increased the circle of potential customers. In addition, there were extensions that could be purchased separately for the generation of color screen content for the color television sets, which were not ubiquitous at the time.

marketing

In the search for future non-European customers, which had already begun in 1975, General Instrument also presented itself to the US toy manufacturer Coleco Industries in March . Shortly afterwards, Coleco ordered the first significant quantities in order to be able to enter the promising video game business with its own game console - the Telstar , which is still to be developed . In April 1975 a hand-wired prototype of the new chip was presented to Magnavox , the leading US manufacturer of video game consoles. Aware of the emerging competition from Coleco, Magnavox also promised the purchase of large quantities that were to be installed in its own console - the later Odyssey 300 . Atari also showed interest in the new circuit. However, the deal did not materialize because of Atari's schedule: General Instrument was unable to deliver the 500,000 chips in demand in September 1975.

After the start of sales in February 1976, one million chips could be sold by August of the same year. Unit prices for bulk buyers like Coleco ranged from $ 5 to $ 6. All of the other electronic parts needed to make a full console cost $ 25-30. This enabled console manufacturers to achieve end-use prices between 60 and 75 US dollars, depending on the equipment. The interest in the new chip was therefore unexpectedly great and as a result, massive delivery bottlenecks quickly arose. Although the five millionth circuit had been delivered in December 1976, many pre-orderers were only able to sell a fraction of the number of consoles they had planned by the 1976 Christmas business.

At the beginning of January 1977 General Instrument sold seven million copies of the AY-3-8500, and in March nine million. The subsequent monthly production output of around one million pieces was accompanied by price reductions also for the accessories, so that the manufacturing costs for a video game console fell to around 40 US dollars by June 1977. As a result of the cheap manufacturability, there was an oversupply of video game consoles in the course of 1977, which resulted in a ruinous fall in prices - the first video game crash. In the course of 1978, the production of consoles had then largely relocated to the Far East. With the exception of Atari, Coleco and Magnavox, in 1978 with Conic, Radofin and others almost exclusively manufacturers from Hong Kong produced game consoles with the AY-3-8500. By 1983 at the latest, the circuit was no longer used to any mention. In Poland, on the other hand, the AmeProd TVG-10 game console with the AY-3-8500 was probably manufactured until 1984.

Presumably as early as 1976 General Instrument launched the AY-3-8550 Ball & Paddle IA, an expanded version of the AY-3-8500 with additional playing options. In the years that followed, both circuit models were used in various game consoles, plug-in modules and televisions from a wide variety of manufacturers. The West German company Interton, for example, produced the AY-3-8500-based consoles Interton Video 3000 and Interton Video 2400 , while Telefunken produced its Palcolor 8610 television with an integrated "game module". In the German Democratic Republic, the electronics company RFT produced the screen game 01 ( BSS 01 for short ) from 1980 . In addition, countless electronics magazines published instructions on how to build a game console yourself.

Modern replicas

The simple architecture of the system and extensive reverse engineering work enable the miniaturized replica of the electronics with today's technical means with at the same time manageable effort. Such a modern realization took place for the first time in 2020 - as with other video game and home computer systems - as an implementation on a programmable logic circuit ( FPGA ) along with an embedding system .

Games

The AY-3-8500 contains a total of seven games, one of which is undocumented by the manufacturer.

Screenshot of Ataris Pong from 1972.

In addition to the two games for use with a light rifle, the circuit includes a total of five variants of Pong , a game that was first published by Atari in 1972 in the form of an arcade machine. Similar to the ping-pong or table tennis from which it is named, two players take turns hitting a ball into the opposing playing field in such a way that it cannot be returned. The rules, the game mechanics and the audiovisual presentation are greatly simplified due to the poorly performing hardware at the time. The playing field is shown in top view and without any textures or other graphic details in black and white. The game pieces are each indicated by an upright block-like line - the paddle . The ball, the movement of which is always straight in the sense of technically simple handling, is represented by a square point that was also easy to generate using the hardware of the time. In order to be able to play this ball back, the racket must be brought into such a vertical position using the console hand controller that it crosses the path of movement of the ball. The impacting ball then ricochets off with an angle of incidence opposite to the angle of incidence and is thus played back to the opposing side. If one of the players misses the ball and it leaves the field of play, the opponent receives a point. The game ends when one of the two players has reached 15 points. The score is indicated by roughly resolved, blocky digits. Pong is one of the simplest possible video games because of the strong abstraction in both the presentation and the game mechanics. It cannot be compared with the much more complex sports games that appeared later.

tennis

Screenshot tennis

Analogous to the real tennis game, two players face each other. The net shown as a line in the middle of the screen only serves to visually separate the playing field and has no influence on the ball. The upper and lower playing field boundaries, which are also shown, are - in contrast to real tennis - integrated into the game because the ball is directed back into the playing field when touched becomes with an angle of reflection opposite to the angle of incidence.

Soccer (soccer, hockey)

Screenshot Soccer

The playing field differs from the tennis court by two additional reflective lines on the right and left edge of the field. These vertical boundaries of the playing field are not continuous, but perforated in the middle. If a ball passes this opening, the goal, the opposing team receives one point. In contrast to the real soccer or hockey team, each of these teams consists of only one striker and one goalkeeper , each in two different halves of the pitch. These are also only shown schematically in line form. Both are simultaneously moved in a vertical direction by the player in order to hit the ball back and score or prevent a goal.

squash

Screenshot squash

As in real squash , two players alternately hit a ball against a fixed, vertical, reflective wall until one of the two parties can no longer play it back.

Practice (practice mode)

Screenshot Practice

The practice mode corresponds to the game of squash for a single player. This allows fine motor skills and hand-eye coordination to be trained in the absence of a second player.

Rifle Shooting Game 1 and 2 (shooting games)

Console with light gun

Both shooting games are based on the principle of clay pigeon shooting . The dummy target to be hit is shown on the screen as a white square on a black background. This pixel moves in a straight line across the screen at a certain angle at a predetermined speed. The player has to aim at this object with a light rifle and "shoot" it by pressing the trigger. In contrast to real shooting, no projectile is emitted by the rifle. Rather, a light-sensitive photocell at the rear end of the gun barrel is used to check whether the bright image point and the gun barrel form a straight line at the time of the trigger. If this condition is not met, not enough light will reach the photocell from the pixel. As a result, it does not provide an evaluation signal for the AY-3-8500 and only the counter for the number of shots is increased. If, on the other hand, there is a hit, the count for the hits is also increased. After 15 shots the number of hits is displayed.

The two game variants Straight Flight and Random Target differ only in that the screen borders reflect the target object or not. In the first shooting game, the target appears on the left edge of the screen and moves to the right until it is either hit or reaches the right edge of the screen. Then it appears again in a different position on the left edge of the screen and moves - now with a different path angle - to the right again. In the second variant, however, the movement always takes place within all four, now reflective, screen boundaries. If you scored a hit in the second variant of the game, the target that is still moving is temporarily hidden. It then reappears on the screen in its newly reached position and the game starts over.

Undocumented game (soccer amateur / professional, handicap)

The game is an expanded version of soccer. On the right side of the field there are now three clubs instead of the two. This game is carried out if none of the other six is ​​chosen.

Setting options

The level of difficulty of the games and thus the entertainment value can be varied using different setting options. For example, the club size, the rebound angle of the ball from the club, the type of ball throw and the speed of the ball can be changed.

General Instrument provides additional operating modes, but they require additional circuitry. Examples are randomly changing ball speeds and three different rebound angles that make the game more interesting. A playing field with a gray background with white and black rackets for squash is also possible in order to be able to better distinguish the rackets, especially if they overlap. A double mode can be implemented for the game of tennis, which enables the connection of four hand controllers and thus a game for four people. However, up to and including 1977 this extension was implemented by only one manufacturer. With the AY-3-8515, General Instrument provided a corresponding converter module for outputting colored playing fields.

Technical information

construction

Metallic layer of the AY-3-8500-Die with conductor tracks and components.

The 28-pin DIL housing of the AY-3-8500 contains an approximately 4.3 mm wide square silicon carrier . All passive and active electronic components, including around 3000 NMOS transistors , are housed in miniature format on this die. This makes the AY-3-8500 one of the highly integrated circuits that are often referred to as LSI chips (from Large Scale Integration ). The current consumption is around 30  mA , which means that the corresponding game consoles can be operated on batteries.

With the AY-5-8500 a 24-pin version appeared only a little later and the American semiconductor manufacturer Texas Instruments brought with its two circuits TMS 1955 and TMS 1965 direct replicas of the AY-3-8500-1 and AY-3-8500 respectively on the market. The successor model AY-3-8550 has extended functionalities, for example the possibility to move the club horizontally. Due to the additional assemblies required, the size of the die increased by about a tenth.

functionality

In contrast to the then much more expensive microprocessors such as the Intel 8080 , the AY-3-8500 is not programmable and it also has no screen memory that can be changed. The course of the game and all graphic data are specified by appropriately connected electronic components inside. In particular, these cannot be modified. Based thereon video game systems are also called for greater clarity of this situation hardwired (English hard-wired ) or specialized (English dedicated called).

Game parameters that can be changed, such as the club size and the rebound angle of the ball, but also additional options such as the 4-player mode, are only set using external circuit elements such as resistors or switches. A game is also selected externally via a switch with which the modules belonging to the respective game are activated within the chip and all those that are not required are deactivated. Different television standards are implemented by different variants of the circuit: the AY-3-8500 for PAL televisions and the AY-3-8500-1 for NTSC devices.

The electrical signals for the television picture are generated in accordance with the technical specifications for the analog tube television sets that were exclusively used in the 1970s . This includes, for example, that an image is made up of lines and that 50 images are to be output per second. This ensures that motion sequences appear as fluid as possible for the viewer and that still images appear largely flicker-free.

Image generation

To build up the picture, the television needs the corresponding control signals for the line and picture changes , which are provided by the AY-3-8500. These sync signals are combined with additional blanking signals and the image data generated by the circuit in an external electronic assembly, the video summer, to form the BAS signal . In most game consoles, a high-frequency modulator and an antenna cable are then fed into the antenna socket on the television.

Sync signals

The generation of the synchronous signals in the AY-3-8500 is based on the use of two binary counters . They divide the externally supplied clock signal with a frequency of 2 M Hz down to the line frequency of 15625 Hz and the frame frequency of 50 Hz. Square-wave pulses derived therefrom, the horizontal and vertical pulses, are then available as synchronization signals at a circuit connection pin. Compared to radio broadcasts, the mix of horizontal and vertical pulses emitted by the AY-3-8500 is less complex. Instead of the fields shifted against each other in the interlace method, congruent fields are generated on the television screen. This simplification has been widely used in the video game field because of its better technical manageability. However, only every second of the 625 screen lines usual in television broadcasts can be displayed, which means that the image generated by the AY-3-8500 with its maximum of 312 lines only has half the vertical resolution of a normal television image. The horizontal resolution, i.e. H. the number of dots per image line is also subject to restrictions compared to radio transmissions. The AY-3-8500 can only generate 128 points per line. A grid of 128 by 312 points is therefore available to generate what is happening on the screen.

Image data and control logic

When building the image, it is checked for each individual grid point one after the other whether there is a graphic object (ball, bat, playing field, score display) or a part of it. The coordinates of such a point are provided by the binary counters already used to generate the synchronization signals. The 7-bit horizontal counter contains one of the 128 possible values ​​for the position within a line and the 9-bit vertical counter contains the corresponding line number. Using 7-bit column decoding or 9-bit row decoding, the control logic carries out all the necessary checks for the current point. If there is a match, d. H. If a graphic object is at the point currently being examined, the so-called character generators of the circuit assigned to this object generate a square pulse. This pulse with a duration of half a microsecond leads to a bright pixel on the screen. If, on the other hand, there is no object at the current position, no pulse is generated and the screen point accordingly remains dark. By increasing the horizontal count, which occurs every half microsecond, the procedure is applied to the next raster point. When the end of a line is reached, the line counter is reset and the vertical count is increased at the same time - and so on. When all 39,936 points of the grid have been processed, the television picture is completely displayed. During the image change, the position counters for the portable clubs and the ball are updated. This is done taking into account collisions and user inputs. If necessary, the game logic updates the score counters.

Ball, bat, score display

In contrast to its real model, the ball is shown as a square. Its position within the grid corresponds to the values ​​of two up / down counters that count once per image, i.e. H. continue counting every 20 milliseconds. With the help of the control logic, the ball coordinates are compared with those of the reflection objects. If they are the same in pairs, a reflection occurs. The control logic differentiates between reflections on horizontally and vertically positioned objects. When reflecting on horizontal objects, the horizontal movement is maintained and the vertical counting direction is reversed. If the ball hits a vertical object, the horizontal counting direction is reversed and the vertical counting direction remains unaffected. Exceptions to this are the permeable center line and, under certain circumstances, the clubs. In the case of clubs, it is possible in some cases to reverse both counter directions, and they can also be permeable to the ball. The latter occurs when the racket is hit by the ball in the back or when the game has ended.

The clubs can be divided into two or four sections. The two inner sections reflect the hitting ball at an angle of 20 degrees, while the two outer sections reflect at an angle of 40 degrees. The horizontal positions of the clubs are fixed. The vertical positions that can be changed by the hand controller are defined by the time difference to the vertical pulse. With the help of further binary counters, the conversion into a corresponding digital address takes place, with the help of which the control logic addresses the character generators for the clubs the next time the image is displayed.

The registration and correct assignment of a gate or fault is also carried out by the control logic during the image change. At the same time, the scores from 0 to 15 are updated accordingly in two 4-bit counters. Because of the high complexity of the circuitry, the counting assembly, together with the associated generator for displaying the digits, occupies about one eighth of the area of ​​the circuit.

Sound generation

The AY-3-8500 delivers square wave signals of three different frequencies, which acoustically accompany the game. When the ball is reflected on clubs and the borders of the playing field, short tones of different heights are emitted. Changes in the score, on the other hand, are accompanied by a longer lasting tone.

Block diagram of the AY-3-8500

reception

Contemporary

In a contemporary market survey published in the US magazine Popular Electronics in late 1976 , the AY-3-8500 was recognized as a pioneer in the use of large-scale integrated circuits (LSI) in the video game industry. Like Magnavox and Atari, he made handheld video games for home use possible for the first time, albeit on a much larger scale. In addition, it is easy to connect and can be used more flexibly than its competing products, which means that a console manufacturer has more configuration and thus pricing options. This slight tailoring of consoles to different needs and target groups is of particular benefit to small and medium-sized companies, said Les Penner, who works for General Instrument, in 1977 at the Gametronic conference, one of the major annual meetings of the video game industry. Les Penner goes on to explain that the circuit was therefore responsible for “almost single-handedly” the game consoles sold in the millions in 1976.

Retrospective

Various Pong consoles with the AY-3-8500 in the Pixel Museum in Schiltigheim

As early as the 1980s, the press unanimously judged that the circuit had changed the video game industry and, according to InfoWorld, even revolutionized it. With the appearance of the AY-3-8500 "everything changed forever", according to the inventor of the first video game console Ralph Baer in 2005 - anyone could now have made a high quality pong game for home use. Thanks to its ease of use, the chip has made the decision easy for many companies like Coleco that have already considered entering the "TV games" industry and enabled high sales figures. On the other hand, companies like First Dimension, which were already active in the industry before it was published and invested considerable sums in the production of expensive predecessor consoles with TTL technology , "fell by the wayside", according to author Steve Bloom. The change in the competitive situation caused by the AY-3-8500 and the associated oversupply led, in the opinion of many authors, to the first collapse of the global video game market in 1977, the Video Game Crash of 1977. According to InfoWorld, even established manufacturers like Atari had to get help from a financially strong investor like Times Warner to ensure the development and manufacture of a new generation of consoles - the later Atari VCS 2600 - needed for survival.

Game consoles with the AY-3-8500 are permanent exhibits in various computer museums, including the Computerspielemuseum Berlin and the Pixel Museum in Schiltigheim, Alsace.

Web links

Commons : AY-3-8500 chip and derived games  - Collection of images, videos and audio files

Individual evidence

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This article was added to the list of excellent articles on June 1, 2020 in this version .