Sega Saturn (Model 2)
The Sega Saturn (Model 2) is a 32-bit fifth-generation home video game console developed by Sega. Released in Japan in late 1994 and internationally in 1995, the Saturn is renowned for its advanced dual-CPU architecture and powerful 2D and 3D graphics capabilities, making it a favourite among retro gaming enthusiasts.
| File:Sega Saturn logo.svg | |
| File:Sega-Saturn-Model2-JP.jpg | |
| Sega Saturn Model 2 (Japanese version) | |
| Specifications | |
|---|---|
| Manufacturer | Sega |
| Type | Home video game console |
| Released | November 22, 1994 (Japan); May 11, 1995 (North America); July 8, 1995 (Europe) |
| Discontinued | 2000 (Japan); 1998 (North America/Europe) |
| Intro price | JP¥44,800 (launch); US$399 (launch) |
| CPU | Dual Hitachi SH-2 32-bit RISC @ 28.6 MHz |
| Memory | 2 MB RAM, 1.54 MB VRAM, 512 KB sound RAM, 4 MB CD buffer RAM |
| Storage | CD-ROM (2× speed), optional backup RAM cartridge |
| Display | 320×224 to 704×480, 16.77 million colours (24-bit, 32,768 on screen) |
| Sound | Yamaha YMF292-F (SCSP): 32-channel PCM/ADPCM, 8–44.1 kHz, 16-bit stereo |
| Dimensions | 260 mm × 230 mm × 83 mm |
| Weight | 2.0 kg |
| OS / Firmware | Sega proprietary BIOS |
| Predecessor | Sega Mega Drive / Genesis |
| Successor | Dreamcast |
| Codename | Saturn |
| Model no. | HST-3220 (Model 2) |
🧠 Architecture and Processor
At the heart of the Sega Saturn is a complex, parallel-processing architecture designed to excel at both 2D sprite manipulation and 3D polygonal graphics. Its main processing components include:
- Dual Hitachi SH-2 32-bit RISC CPUs running at 28.6 MHz, operating in parallel for increased performance.
- Hitachi SH-1 as the CD-ROM controller.
- Two custom video display processors:
- VDP1 – Handles sprites and polygons (2D/3D graphics).
- VDP2 – Manages backgrounds, scrolling, and effects.
- Additional support chips for sound, DMA, and I/O.
This architecture allowed for advanced graphical effects, but also posed programming challenges due to its complexity.
💾 Memory and Storage
The Saturn Model 2 features a diverse memory map optimised for graphics and sound:
- 2 MB main RAM
- 1.54 MB VRAM (split between VDP1 and VDP2)
- 512 KB sound RAM
- 4 MB CD-ROM buffer RAM
- 32 KB backup RAM (internal), expandable via optional cartridge
Storage is provided by a 2× speed CD-ROM drive, supporting up to 640 MB per disc. Game saves are stored in internal backup RAM or on external RAM cartridges.
🖥️ Display and Graphics
The Saturn's graphics subsystem is built around its dual VDPs:
- Resolution: 320×224 to 704×480 pixels (interlaced and non-interlaced modes)
- Colour palette: 16.77 million (24-bit), with up to 32,768 colours displayed simultaneously
- VDP1: Renders sprites, polygons, scaling, rotation, and texture mapping
- VDP2: Handles up to five scrolling background planes, transparency, and special effects
Hardware support for both 2D and 3D graphics made the Saturn especially strong for arcade-style and sprite-based games.
🔊 Sound Capabilities
Audio on the Saturn is powered by the Yamaha YMF292-F (SCSP) sound processor:
- 32 sound channels supporting PCM and ADPCM playback
- Sampling rates from 8 kHz to 44.1 kHz, 16-bit stereo output
- Integrated DSP for effects such as reverb and modulation
- Additional Motorola 68EC000 CPU (11.3 MHz) for sound control
This robust sound system enabled high-quality music and effects, including streaming audio from CD.
🎮 Input/Output and Expansion
The Saturn Model 2 offers a wide range of connectivity and expansion options:
- Controller ports: 2 × proprietary 9-pin connectors (supporting digital and analogue pads, multitap)
- AV output: Composite video, S-Video, RGB SCART (PAL/JP), stereo audio
- Serial port: For link cable multiplayer
- Cartridge slot: For backup RAM, ROM cartridges, and RAM expansion (up to 4 MB for certain games)
- Communication connector: For modem or network peripherals (Japan only)
- Power: Internal PSU (100–240 V, region dependent)
🔍 PCB Schematics & Service Manual
The Model 2 Saturn features a revised mainboard with integrated components and simplified circuitry compared to the original model. Service documentation and schematics are available for maintenance and repair.
| Mainboard (Model 2) | Power Supply Unit |
|---|---|
- For detailed board layouts and service procedures, refer to the Sega Saturn Service Manual (Model 2).
📷 Gallery
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Sega Saturn Model 2 (Japan)
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Sega Saturn Model 2 (Europe)
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Model 2 mainboard
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Power supply unit
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Standard Saturn controller (Model 2)
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Cartridge slot detail
