VCO Object

From Sega Retro

VCO Object arcade hardware was used by Sega for a brief period between 1981 and 1983. It was Sega's earliest attempt at creating hardware specifically designed for sprite scaling, something that would be widely used in the Super Scaler series of arcade hardware (Sega Hang-On, Sega OutRun, Sega X Board, Sega Y Board, Sega System 32), and a handful of Sega System boards in between.

The hardware debuted with the release of Turbo, and is also known as the Turbo Hardware because of this. It is also known as the Sega Z80-3D system.[1]

All VCO Object games rely on external LED displays for parts of the HUD. This means extra precautions must be taken when attempting to emulate VCO Object games.

Hardware

It was the first system specifically designed for pseudo-3D sprite-scaling graphics, using an analog scaling technique, with Voltage Controlled Oscillators (VCOs) generating clock signals controlling the data fetched from the sprite/object ROM; the slower the clock signal, the larger the sprite on screen.[2] In 1982, SubRoc-3D also introduced an active shutter 3D system, jointly developed by Sega with Matsushita (now Panasonic).[3]

Technical Specifications

VCO Object Specifications

  • CPU: Z80 @ 5 MHz (8-bit & 16-bit instructions @ 0.725 MIPS)
  • Sound board: Sega Sound Board
  • Video resolution:[4][5]
    • Standard resolution:
      • Horizontal: 256×224 (display), 320×264 (overscan)
      • Vertical: 224×256 (display), 264×320 (overscan)
    • Analog scaling resolution:
      • Horizontal: 512×224 (display), 640×264 (overscan)
      • Vertical: 224×512 (display), 264×640 (overscan)
  • Refresh rate: 60 Hz (V-sync)
  • Frame rate: 60 frames per second
  • Color palette: 832
  • Colors on screen: 256
  • Background planes:
  • Sprite capabilities: Pseudo-3D sprite-scaling (analog scaling), line buffer, 64 sprites on screen, 16 sprites per scanline, 4 to 8 colors per sprite
    • Pixel clock cycles: 4.992 MHz (standard) to 9.984 MHz (scaling)
    • Fillrate: 4.992 million (standard) to 9.984 million (scaling) pixels/texels per second, 83,200 (standard) to 166,400 (scaling) pixels/texels per frame
    • Sprite pixels/texels per scanline: 315 (standard) to 630 (scaling)

SubRoc-3D Specifications

SubRoc-3D featured the following hardware changes and upgrades in mid-1982:

Buck Rogers Specifications

Buck Rogers: Planet of Zoom featured the following hardware upgrades in late 1982:

  • CPU: 2× Z80 @ 5 MHz (8-bit & 16-bit instructions @ 1.45 MIPS)
  • Frame rate: 60 frames per second
  • Color palette: 1536
  • Colors on screen: 1024

List of VCO Object Games

Only three games make use of VCO Object hardware:


Sega arcade boards
Originating in arcades









Console-based hardware








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PC-based hardware








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