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.
Contents
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
- Board composition: CPU board, Sound board[4]
- CPU: Zilog Z80 @ 5 MHz (8-bit & 16-bit instructions @ 0.725 MIPS)
- Sound board: Sega Sound Board
- Sound chip: Custom
- Audio output: Stereo
- Video scaling hardware: 8× Voltage Controlled Oscillators (VCOs)
- RAM: 12 KB[4]
- Video resolution:[5][6]
- 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:[4]
- RAM: 14.75 KB
- Main: 6.25 KB (2 KB main, 2 KB analog reset, 256 bytes input, 2 KB handle)
- Video: 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)
- Frame rate: 30 frames per second
- Color palette: 768
- Stereoscopic 3D: Sega-Matsushita active shutter 3D system
Zoom Specifications
Zoom 909 and Buck Rogers: Planet of Zoom featured the following hardware upgrades in late 1982:[4]
- Board composition: CPU board, Sound board, ROM board
- CPU: Zilog Z80 & Sega 315-5014 (Z80) @ 5 MHz (8-bit & 16-bit instructions @ 1.45 MIPS)
- RAM: 104 KB (96 KB DRAM, 8 KB high-speed SRAM)
- Main: 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)
- Video: 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)
- Frame rate: 60 frames per second
- Color palette: 1536
- Colors on screen: 1024
List of VCO Object Games
Only several games make use of VCO Object hardware:
- Turbo (1981)
- SubRoc-3D (1982)
- Zoom 909 (1982)
- Buck Rogers: Planet of Zoom/Zoom 909 (1982)
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