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VCO Object

From Sega Retro

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Fast facts on VCO Object
Manufacturer: Sega
Main processor: Zilog Z80
Release Date RRP Code
Arcade
World
1981-10  ?


VCO Object arcade hardware was used by Sega for a brief period between 1981 and 1983. It was Sega's second attempt at creating hardware specifically designed for sprite scaling (after the Sega Fonz hardware in 1976), something that would be widely used in the Super Scaler series of arcade hardware (Sega Hang-On, Sega OutRun, X Board, Y Board, 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).Media:SubRoc3D VCOObject US Flyer.pdf[3]

Technical specifications

VCO Object specifications

Graphics

  • Graphics chipset:[7]
    • 315-0138: Custom Chip PA-06R (PAL16R4MJ)
    • 315-0139: Custom Chip PA-06L (PAL16L8MJ)
    • 12x 314-0101: 74LS283 4-bit Binary Full Adder with Fast Carry[8]
    • Video scaling hardware: 8x Voltage Controlled Oscillators (VCOs)[2]
  • Video clock rate: 9.984 MHz[9]
    • Pixel clock rate: 4.992 MHz[5]
  • Video resolution:[5]
    • Horizontal: 256×224 (display), 320×264 (overscan)
    • Vertical: 224×256 (display), 264×320 (overscan)
  • Analog scaling resolution:[9]
    • Horizontal: 512×224 (display), 640×264 (overscan)
    • Vertical: 224×512 (display), 264×640 (overscan)
  • Refresh rate: 59.090909 Hz (V-sync)[5]
  • Color palette: 832[5]
  • 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[1][5]
    • Sprite sizes: 8×8 to 256×224 texels
    • Sprites on screen: 128 sprites (8 KB sprite position RAM, 8 bytes per sprite position)
    • Fillrate: 4.992 MPixels/s
    • Sprites per scanline: 16 sprites, 322 texels

Memory

SubRoc-3D specifications

SubRoc-3D featured the following hardware changes and upgrades in mid-1982:[5]

  • Frame rate: 30 frames per second
  • Color palette: 768
  • Stereoscopic 3D: Sega-Matsushita active shutter 3D system
  • RAM: 14.75 KB
    • Main RAM: 6.25 KB (2 KB main, 2 KB analog reset, 256 bytes input, 2 KB handle)
    • VRAM: 8.5 KB (2 KB video, 1 KB sprite line buffer, 1 KB sprite position, 2 KB characters, 512 bytes collision, 2 KB collision clear)
  • ROM: 302.5 KB
    • Main ROM: 40 KB
    • VROM: 262.5 KB (256 KB sprites, 4 KB foreground tiles, 768 bytes color, 1.75 KB other)

Zoom specifications

Zoom 909 and Buck Rogers: Planet of Zoom featured the following hardware upgrades in late 1982:[5]

  • Board composition: CPU board, Sound board, ROM board
  • CPU: 2x Z80 @ 5 MHz (1.45 MIPS)
    • Zilog Z80 @ 5 MHz
    • Sega 315-5014 (Z80) @ 5 MHz
  • Frame rate: 60 frames per second
  • Color palette: 1536
    • Colors on screen: 1024
  • RAM: 104 KB (SRAM)
    • Main RAM: 39.5 KB (2 KB main, 2 KB analog reset, 256 bytes input, 2 KB handle, 2 KB CPU 2 mirror, 31.25 KB other)
    • VRAM: 64.5 KB (2 KB video, 1 KB sprite line buffer, 1 KB sprite position, 2 KB characters, 512 bytes collision, 2 KB collision clear, 56 KB bitmap)
  • ROM: 310.5625 KB
    • Main ROM: 40 KB
    • VROM: 270.5625 KB (256 KB sprites, 4 KB foreground tiles, 9.5 KB color, 1.0625 KB other)

List of games

Only three games make use of VCO Object hardware:

References

Sega Arcade Boards
Originating in Arcades
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08
Fonz Galaxian Zaxxon Appoooh X Board Model 2 Hikaru Atomiswave
Blockade G80 Hang-On / Space Harrier Model 1 H1 Model 3 NAOMI 2
VIC Dual System 1 System 24 NAOMI
VCO Object LaserDisc System SP
System 2 System 18
System 16
OutRun System 32
Gigas
Y Board
Based on Consumer Hardware
83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
SG-1000 System E System C Triforce Europa-R RingEdge 2
Mega-Tech System Sega Titan Video Chihiro Nu
Mega Play Lindbergh
RingEdge
RingWide
Hardware Series / Generations
1960s 1970s 1980s 1990s 2000s 2010s
Electro-mechanical systems Sega System series Sega NAOMI series
Discrete logic systems Super Scaler series Post-NAOMI systems
Pre-System boards Sega Model series