Sega Saturn (Model 1)

Sega Saturn (Model 1)
	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 (Model 2)
Successor	Sega Saturn (Model 2)
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
Sega Saturn Model 1 Mainboard	File:Sega saturn va0.5 schematics.pdf

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

Gallery

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