VCO Object
From Sega Retro
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VCO Object | |||||
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Manufacturer: Sega | |||||
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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.
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
- Board composition: CPU Board, Sound Board, P-ROM Board[4][5]
- CPU: Zilog Z80 @ 5 MHz (8/16-bit instructions, 0.725 MIPS)
- Sound board: Sega Sound Board
- Sound chip: Custom
- Audio output: Stereo
Graphics
- Graphics chipset:[6]
- Video clock rate: 9.984 MHz[7]
- 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:[7]
- Refresh rate: 59.090909 Hz (V-sync)[5]
- Frame rate: 59.090909 frames per second
- Color palette: 832[5]
- 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[1][5]
Memory
SubRoc-3D
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
- 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
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 VCO Object Games
Only three games make use of VCO Object hardware:
- Turbo (1981)
- SubRoc-3D (1982)
- Zoom 909 / Buck Rogers: Planet of Zoom (1982)
References
- ↑ 1.0 1.1 1.2 Sega Z80-3D system (video hardware) (MAME)
- ↑ 2.0 2.1 Sega VCO Object Hardware (System 16)
- ↑ File:SubRoc3D VCOObject US Flyer.pdf
- ↑ File:Turbo Schematics.pdf
- ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 Sega Z80-3D system (MAME)
- ↑ 6.0 6.1 Turbo: Operating Instructions and Service Manual (page 106)
- ↑ 7.0 7.1 Sega Z80-3D system (data) (MAME)
- ↑ Turbo (MAME)
- ↑ File:Turbo Schematics.pdf, page 19
- ↑ File:Turbo Schematics.pdf, page 21
- ↑ File:MB8128 datasheet.pdf
- ↑ File:NTE2764 datasheet.pdf
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