Sega Saturn (Model 1)

Sega Saturn (Model 1)

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File:Sega-Saturn-Model1-JP.jpg
Sega Saturn Model 1 (Japanese launch version)
Specifications
Manufacturer	Sega
Type	Home video game console
Released	JP: 22 November 1994 NA: 11 May 1995 EU: 8 July 1995
Discontinued	1998 (JP), 1998 (NA), 1998 (EU)
Intro price	JP: ¥44,800 NA: US$399 EU: £399.99
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 pixels, 16.77 million colours (24-bit, 16-bit output)
Sound	Yamaha YMF292-F (SCSP): 32 channels, 16-bit PCM, 8 FM channels
Dimensions	260 mm × 230 mm × 83 mm
Weight	2.0 kg
OS / Firmware	Proprietary Sega Saturn OS (in ROM)
Predecessor	Sega Mega Drive / Genesis
Successor	Dreamcast
Codename	"Saturn"
Model no.	HST-3200 (JP), MK-80000 (NA/EU)

The Sega Saturn (Model 1) is a 32-bit fifth-generation home video game console developed by Sega and released in Japan in November 1994, followed by North America and Europe in 1995. Renowned for its complex dual-CPU architecture and advanced 2D/3D graphics capabilities, the Saturn was Sega's answer to the Sony PlayStation and Nintendo 64.

🧠 Architecture and Processor

At the heart of the Saturn is a sophisticated multi-processor design:

• Main CPU: Dual Hitachi SH-2 32-bit RISC processors, each running at 28.6 MHz, connected via a custom bus.
• Video Display Processors: Two custom VDPs:
  • VDP1 – Handles sprites, polygons, and texture mapping for 2D/3D graphics.
  • VDP2 – Manages backgrounds, scrolling, and advanced effects.
• Sub-CPUs and Co-processors:
  • Hitachi SH-1 (CD-ROM controller)
  • Motorola 68EC000 (sound CPU)
  • Custom DSPs for geometry and audio processing.

This parallel architecture enabled advanced graphical effects but presented programming challenges, impacting third-party development.

💾 Memory and Storage

The Saturn's memory subsystem includes:

• 2 MB main RAM
• 1.54 MB video RAM (VDP1: 512 KB, VDP2: 1 MB)
• 512 KB sound RAM
• 4 MB CD-ROM buffer RAM
• 32 KB backup RAM (internal, battery-backed; expandable via external cartridge)

Storage is provided by a double-speed (2×) CD-ROM drive, supporting up to 640 MB per disc. Save data is stored in internal backup RAM or optional external RAM cartridges.

🖥️ Display and Graphics

The Saturn excels at 2D graphics and supports 3D rendering:

• Resolution: Ranges from 320×224 up to 704×480 pixels (interlaced and non-interlaced modes)
• Colour: Up to 16.77 million colours (24-bit palette), with 16-bit output per pixel
• Sprites: Hardware support for scaling, rotation, and transparency
• Backgrounds: Multiple scrolling backgrounds, line scrolling, and colour effects via VDP2
• 3D Graphics: Flat and texture-mapped polygons, Gouraud shading, and mesh effects

The Saturn's architecture was optimised for 2D arcade-style games but could deliver impressive 3D visuals when fully utilised.

🔊 Sound Capabilities

Audio on the Saturn is handled by the Yamaha YMF292-F (SCSP) sound processor:

• 32 sound channels (16-bit PCM or 8 FM synthesis)
• 44.1 kHz sampling rate
• DSP effects: reverb, chorus, and modulation
• Sound RAM: 512 KB dedicated
• CD-DA playback and Red Book audio support

The system's sound hardware enabled rich, multi-layered music and effects, rivaling dedicated audio workstations of the era.

🎮 Input/Output and Expansion

The Saturn provides a range of connectivity and expansion options:

• Controller ports: 2 standard 9-pin Sega controller ports (supporting multitap for up to 6 players)
• AV output: Composite video, S-Video, and RGB SCART (PAL/JP models)
• Stereo audio output
• Backup RAM cartridge slot (for save data expansion)
• Communication connector (for link cable and network peripherals in some regions)
• Cartridge slot (for memory expansion, cheat devices, and region adapters)
• Serial port (for modem and link cable, Japan only)
• Power supply: Internal

🔍 PCB Schematics & Service Manual

Saturn Model 1 Mainboard	Mainboard Schematic
File:SegaSaturn-Model1-LogicBoard.jpg Sega Saturn Model 1 Mainboard	File:SegaSaturn-Model1-Schematic.png Sega Saturn Model 1 Mainboard Schematic

The official Sega Saturn Service Manual and schematics are available via Sega Saturn Service Manual (PDF) and Sega Saturn Technical Reference.

📷 Gallery

• Sega Saturn Model 1 (Japanese launch)
  Sega Saturn Model 1 (Japanese launch)
• Saturn Model 1 mainboard (top view)
  Saturn Model 1 mainboard (top view)
• Sega Saturn Model 1 controller
  Sega Saturn Model 1 controller
• Saturn CD-ROM drive assembly
  Saturn CD-ROM drive assembly
• Official Backup RAM Cartridge
  Official Backup RAM Cartridge

🧪 Related Pages

• Sega Saturn General Maintenance
• Sega Saturn Troubleshooting Guide
• Sega Saturn Controller Repair Guide
• Sega Saturn Capacitor Replacement Guide