Microvision

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Microvision

The Microvision was the very first hand-held game console using interchangeable cartridges. It was released by the Milton Bradley Company in November 1979^[1]. The Microvision was designed by Jay Smith, the engineer who would later design the Vectrex gaming console. The Microvision's combination of portability and a cartridge-based system led to moderate success, with Smith Engineering grossing $8 million in the first year of the system's release. The hand-held also appeared in the movie Friday the 13th Part 2. However, very few cartridges, a small screen, and a lack of support from established home video game companies led to its demise in 1981.^[2]

Production

The first Microvision cartridges were made with both Intel 8021 and Texas Instruments TMS1100 processors. Due to purchasing issues, Milton Bradley switched to using TMS1100 processors exclusively. The TMS1100 was a more primitive device, but offered more memory and lower power consumption than the 8021. First-revision Microvisions needed two batteries due to the 8021's higher power consumption, but later units (designed for the TMS1100) only had one active battery holder. Even though the battery compartment was designed to allow the two 9-volt batteries to be inserted with proper polarity of positive and negative terminals, when a battery was forcefully improperly oriented, while the other battery was properly oriented, the two batteries would be shorted and they would overheat. The solution was to remove termials for one of the batteries to prevent this hazard. Due to the high cost of changing production molds, Milton Bradley did not eliminate the second battery compartment, but instead removed its terminals and called it the spare battery holder.

Problems

Microvision units and cartridges are now very rare. Those that are still in existence are susceptible to three main problems: "screen rot," ESD damage, and keypad destruction.

Screen rot

The manufacturing process used to create the Microvision's LCD was primitive by today's standards. Poor sealing and impurities introduced during manufacture has resulted in the condition known as screen rot. The liquid crystal spontaneously leaks and permanently darkens, resulting in a game unit that still plays but is unable to properly draw the screen. While extreme heat (such as resulting from leaving the unit in the sun) can instantly destroy the screen, there is nothing that can be done to prevent screen rot in most Microvisions.^{[citation needed]}

ESD damage

A major design problem involves the fact that the microprocessor (which is inside the top of each cartridge) lacks ESD protection and is directly connected to the copper pins which normally connect the cartridge to the Microvision unit. If the user opens the protective sliding door that covers the pins, the processor can be exposed to any electric charge the user has built up. If the user has built up a substantial charge, the discharge can jump around the door's edge or pass through the door itself (dielectric breakdown). The low-voltage integrated circuit inside the cartridge is extremely ESD sensitive, and can be destroyed by an event of only a few dozen volts which cannot even be felt by the person, delivering a fatal shock to the game unit. This phenomenon was described in detail by John Elder Robison (a former Milton Bradley engineer) in his book Look Me in the Eye.

Keypad destruction

Instead of having buttons on a separate controller, the Microvision unit had a twelve-button keypad, with the switches buried under a thick layer of flexible plastic. To align the user's fingers with the hidden buttons, the cartridges had cutouts in their bottom (over the keypad). As different games required different button functions, the cutouts were covered with a thin printed piece of plastic, which identified the buttons' functions in that game. The problem with this design is that pressing on the buttons stretched the printed plastic, resulting in the thin material stretching and eventually tearing. Having fingernails exacerbated the condition.

Technical specifications

• CPU: Intel 8021/TI TMS1100 (on cartridge)
• Screen type and resolution: 16 x 16 pixel LCD
• Register width: 4 bit (TMS1100), 8 bit (8021)
• Processor speed: 100 kHz
• RAM: 32 nybbles (16 8-bit bytes, integrated into CPU)
• ROM: 2K
• Cartridge ROM: 2K masked (integrated into CPU; each game's CPU was different)
• Video Display Processor: Custom (made by Hughes)
• Sound: Piezo beeper
• Input: Twelve button keypad, one paddle
• Power requirements: One 9 volt battery (TMS1100 processors), Two 9 volt batteries (Intel 8021 processors)

Games

Star Trek: Phaser Strike

• 1979
  • Block Buster
  • Bowling
  • Connect Four
  • Mindbuster
  • Pinball
  • Star Trek: Phaser Strike (later just Phaser Strike)
  • Vegas Slots
• 1980
  • Baseball
  • Sea Duel
• 1981
  • Alien Raiders
  • Cosmic Hunter
• 1982
  • Barrage (Not released - no known prototypes)
  • Super Blockbuster (Released only in Europe)

See also

• Mattel Auto Race - an early handheld developed prior to Microvision.

External links

• Microvision Paper Model
• Milton Bradley Microvision information
• Microvision simulation page

References

A Brief History of Handheld Video Games by Donald Melanson, Engadget.com