Bubble memory, developed by Bell Labs in 1967, was a non-volatile storage technology that used small magnetic domains to store data. Initially, it found applications in rugged environments like Bell Telephone's digital recording systems and NASA spacecraft, valued for its reliability. Intel later produced a 1-megabit bubble memory chip used in early portable computers, offering faster performance than floppy disks. In 1985, Konami uniquely adopted bubble memory for its GX400 arcade system, primarily to combat widespread piracy, marketing it as "copy-proof." The technology worked by generating and moving magnetic bubbles along etched "racetrack" patterns using rotating magnetic fields, with a "seed bubble" creating new data bits. However, despite its innovative approach, bubble memory faced commercial failure. Its downfall was attributed to the rise of cheaper alternatives like DRAM and hard disks, its high sensitivity to power loss and electromagnetic interference, and a notable 10-minute warm-up time required before arcade games could start. Konami eventually abandoned bubble memory, switching the GX400 to ROM-based game cards.
Konami GX400 system board with bubble memory cartridge
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Introduction to Bubble Memory and Konami's Innovation [0:00]
Konami sought to increase profit and give arcade operators confidence in purchasing their games amidst the competitive 1985 arcade market.
Konami's solution involved developing an arcade system board with swappable games, similar to home consoles but with more powerful and expensive custom hardware.
Unlike other developers, Konami uniquely integrated bubble memory into their system.
History and Early Applications of Bubble Memory [0:01:22]
Development: Bubble memory was developed at Bell Labs in 1967.
It was a non-volatile storage medium, meaning data persisted even when powered off.
It operated on the principle of using small cylindrical magnetic domains (bubbles) to store data.
Early Investments and Applications:
In the early 1970s, companies like Texas Instruments, Intel, and Hitachi invested in the technology.
Bell Telephone [1977]: Used it for their digital recording and playback machines, such as the automated "call cannot be completed" messages.
British Telecom [1982]: Advertised systems like the Plessey 4660/20 Telex and data switch with microprocessor-based program control and bubble memory.
British Telecom Journal advertising a Plessey 4660/20 Telex and data switch with bubble memory.
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Ruggedness and Reliability: Bubble memory was considered rugged and reliable, leading to its use in critical systems.
Rockwell: Utilized it in blackbox flight recorders.
NASA [1978]: Evaluated bubble memory for spacecraft, concluding it could operate reliably over long periods at low error rates, with no detectable wear-out or aging mechanisms.
Intel's Contribution: Intel produced the first 1-megabit bubble memory storage device, the Intel 7110, in 1979, quadrupling previous capacities to 128KB of data.
Intel 7110, the first 1-megabit bubble memory storage device.
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Home Computing Applications (Early 1980s):
Grid Compass [1982]: This portable computer, considered by some as the first laptop, contained the Intel 7110 memory module. It was expensive, costing $8,000-$10,000.
Apple II [1982]: A bubble memory card for the Apple II reportedly ran 3 to 5 times faster than a floppy disk.
Bubble memory was positioned between high-end solid-state memory and magnetic media (cassette tapes, floppy disks).
Emergence of Cheaper Alternatives: The arrival of more affordable memory alternatives in the 1970s, such as Dynamic RAM (DRAM), EPROMs, and later hard disks, made bubble memory less appealing.
Sensitivity Issues: It was found to be very sensitive to power loss and electromagnetic interference, which are common in arcade environments.
Industry Abandonment: By 1981, companies like Texas Instruments had abandoned bubble memory, with only a few, like Intel, continuing to develop it. By 1985, the technology was in decline.
Konami's Rationale for Using Bubble Memory [0:05:13]
Despite the general decline, Konami chose bubble memory for its video game arcade systems in 1985 primarily to combat piracy.
Anti-Piracy Measure: Bootlegging was rampant in the mid-80s arcade industry, where ROM chips could be easily copied using gang programmers.
John Richards demonstrating how ROM chips were easily copied using a gang programmer.
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"Copy-Proof" System: Konami marketed its Bubble System as "copy-proof," guaranteeing "smooth and steady distribution," which was a major selling point.
Konami Bubble System (GX400) Hardware and Games [0:06:07]
Konami's GX400 system board integrated the bubble memory game cartridge.
Processor: It featured a Motorola 68000 CPU running at just over 9 MHz.
Sound: A Zilog Z80 managed sound alongside two AY chips and Konami's proprietary Sound Creative Chip (SCC), a two-channel wavetable sound generator.
Speech Synthesis: It included a Sanyo developed VL5030 chip specifically designed for speech synthesis.
Graphics: Custom chips handled sprites, tile maps, and video timing, enabling 2048 colors on screen simultaneously.
Notable Games: The system hosted several popular arcade games, including:
Gradius (also known as Nemesis overseas)
TwinBee
Galactic Warriors
Konami GT (also known as RF2)
Screenshot from Konami GT, one of the arcade games on the Bubble System.
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Richard explains the intricate workings of bubble memory using a physical demonstration with balls.
Basic Principle:
Bell Labs discovered that a gallium garnet substrate with a very thin magnetic layer could produce a field of magnetically doped material.
Introducing a magnetic field creates "domains" or magnetic "bubbles" (small cylindrical magnetic regions within the material).
Diagram illustrating how magnetic domains (bubbles) form on a substrate.
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These domains naturally cluster together to minimize energy.
By introducing more energy, the domains cluster tighter and then "pop" into single, spaced-out bubbles, representing a "bit" of data (1 or 0).
Controlling Bubble Movement ("Racetrack"):
The breakthrough was finding a way to control and sequence these bubbles.
Early methods involved etching small magnetic T's and I's, which evolved into "chevron patterns" on the substrate.
These patterns form a "racetrack" that guides the bubbles.
A "racetrack" pattern made of chevrons used to guide magnetic bubbles.
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Magnetic Field Coils: To move the bubbles along the racetrack in a desired direction, magnetic field coils are wrapped around the substrate.
One coil is oriented in the X-direction and another in the Y-direction, effectively "sandwiching" the racetrack.
By modulating the energy input, a rotating magnetic field is generated, similar to how a motor spins. This field quickly moves the bubbles along the racetrack.
Diagram showing how permanent magnets and field coils generate a rotating magnetic field to move bubbles.
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Permalloy Jacket: A crucial component is the permalloy metal jacket that wraps around the entire assembly.
It seals both ends and controls the generation and concentration of magnetic flux, ensuring the energy is focused to make the system work.
Writing Data (Generating Bubbles):
Initially, the bubble memory racetrack is "empty" (all zeros).
To write a "1" (create a bubble), a "seed bubble" is used.
This seed bubble is slightly larger and requires less energy to "pinch off" a new bubble compared to creating one from scratch using the XY planes.
The seed bubble pops a new bubble onto the racetrack at a known, controlled point.
To write a "0", no bubble is generated at that point in the sequence.
The "seed bubble" can be intentionally destroyed, making the memory read-only.
Diagram of a bubble memory racetrack showing points for generating, detecting, and annihilating bubbles.
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The Konami Bubble System ultimately did not achieve commercial success.
High Failure Rate: The majority of Konami Bubble System boards are non-functional due to their extreme sensitivity.
They are easily destroyed by magnetic interference, power loss, overheating, or physical mistreatment.
Slow Startup Time: A significant operational drawback was the required 10-minute warm-up period before a game could start.
Manual indicating a 10-minute warm-up period is required for the Konami Bubble System.
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The system needed to reach an operating temperature of 30-40°C.
A large fan on the board was used to cool the cartridge if it overheated, keeping it within the optimal temperature range.
Upon power-on, a countdown timer and "morning music" would play during this warm-up phase.
The Konami Bubble System displaying a countdown timer during its warm-up phase.
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Contributing Factors to Demise:
Slow startup times were commercially unacceptable for arcades.
The system was more expensive than most ROM-based alternatives.
Its sensitivity to electromagnetic interference and power loss proved problematic in real-world arcade environments.
Konami's Pivot: Konami eventually replaced the bubble memory software with ROM-based game cards on their GX400 system board, and existing bubble games were ported to ROMs.
Modern Emulation: Devices like the "Bubble Drive 8" exist to emulate the data stream from the bubble system, allowing non-functional boards to run games, but these are in short supply.
