Sega 32X

The 32X, codenamed Project Mars, is a hardware add-on system developed by Sega for the Sega Genesis console.

Released worldwide in 1994, the 32X was designed to extend the Genesis' lifespan by giving it significantly enhanced 32-bit processing power and texture-mapped 3D capabilities. It was succeeded by the Sega Saturn.

The 32X went under different names in the regions that it was released in. In Japan, it was named the Sega Super 32X (Japanese: セガスーパー32X Sega Sūpā 32X). In North America, it was sold as the Sega Genesis 32X. It was dubbed the Sega Mega Drive 32X in Europe, Asia, and Australia. In Brazil, it was named the Mega 32X. It was distributed in South Korea by Samsung as the Samsung Super 32X (Korean: 삼성수퍼 32X Samseong Supeo 32X).

General Overview

The 32X attaches to the Genesis by plugging into the console's cartridge slot, designed as a permanent addition to a Genesis setup, acting as both a means of playing 32X cartridges and a passthrough device for playing standard Genesis games. The 32X's video encoder is of a slightly higher build quality than those usually found in later iterations of the Genesis, potentially resulting in a slightly clearer image when playing Genesis titles. A plastic spacer piece comes included with the 32X to ensure that it fits into the console securely.

The 32X is designed to play its own game cartridges, which are designed to take advantage of the enhancements of the system. The cartridges cannot fit onto the cartridge slot of the standard Genesis console (or any console produced since), and the setup is designed that it doesn't interfere with an attached Sega CD unit. But, like the Sega CD, the 32X can't function on its own.

On the topic of the Sega CD, when both it and the 32X are attached to the Genesis, it creates the Sega CD 32X set-up, which allows the user to play any of the six enhanced Sega CD 32X software titles. Its ability to access a wider palette of colors allows for higher quality FMV than a standard Sega CD, whose FMV games were often criticized for their lack of color and detail.

Despite the lower price and its positioning as an inexpensive entry into 32-bit gaming, the 32X was commercial failure, due to a shallow library of titles, the oncoming arrival of the Sega Saturn, Sony PlayStation, and Nintendo 64, bad market timing, and the resulting market fragmentation of the Genesis. Not helping things, was that many developers did not want to make games for an add-on system that was a technological dead end.

Drawbacks

One major issue is that before the system is even switched on, the 32X requires its own AC adapter, and a second connection to the Genesis console from the back of it. If the user also has a Sega CD, this means no less than three power adapters are required (plus a fourth for a TV). Both the AC adapter and 32X Connector Cable are bespoke units - the AC adapter is more common, as it is identical to that seen with the second model Genesis (though is not often covered by universal AC adapters), but the 32X Connector Cable is unique to the 32X and was not sold separately (though third parties variants exist).

Furthermore, Sega's AC adapters of the day were designed so that the transformer was located around the plug area. This often resulted in several bulky units obstructing surrounding sockets. Due to the extra space required just to plug the console into the wall, Sega eventually released their own Sega Power Strip in North America.

Dynamite Headdy

A port of Dynamite Headdy was planned for the 32X, but due to the system's low popularity, it was cancelled.

Technical Specifications

• Main CPU: 2x Hitachi SH-2 (SH7095) 32-bit RISC processors
  • Clock speed: 23.01136 MHz (NTSC), 22.801467 MHz (PAL)
  • Clock cycles: 46.022721 MHz (NTSC, 23.01136 MHz per SH-2), 45.602934 MHz (PAL, 22.801467 MHz per SH-2)
  • 2x CPU cores: 32‑bit RISC instructions/registers, up to 4 instructions/cycle (2 instructions/cycle per SH-2), 1.3 MIPS per MHz, 59.829537 MIPS (NTSC, 29.914768 MIPS per SH-2), 59.283814 MIPS (PAL, 29.641907 MIPS per SH-2)
  • 4x internal fixed‑point math processors: 2x MULT multiplier DSP, 2x DIVU division units, parallel processing
  • 2x MULT multiplier DSP: 46.022721 MOPS (NTSC, 23.01136 MOPS per SH-2), 45.602934 MOPS (PAL, 22.801467 MOPS per SH-2)
  • 2x DIVU division units: 16/32/64-bit division, 1,180,069 divides/sec
  • 2x DMA units: 2x DMAC (Direct Memory Access Controller), parallel processing
  • Bus width: 64‑bit (2× 32‑bit) internal, 32‑bit external
• CPU co-processors: Overlay/Underlay processors
  • Genesis CPU:
    • Motorola M68000 — 7.670453 MHz (NTSC), 7.600489 MHz (PAL), 16/32-bit instructions, 32-bit internal data bus, 16-bit external data bus, 1.342329 MIPS (NTSC), 1.330085 MIPS (PAL)
    • Zilog Z80 — 3.579545 MHz (NTSC), 3.546894 MHz (PAL), 8/16-bit instructions, 8-bit data bus, 0.519034 MIPS (NTSC), 0.514299 MIPS (PAL)
  • Sega CD CPU: Motorola M68000 — 12.5 MHz, 2.1875 MIPS

• Graphics
  • 32X graphics chip: Sega 32X VDP (Sega Custom LSI) @ 23.01136 MHz (NTSC), 22.801467 MHz (PAL)
  • Data bus width: 32-bit (16-bit per framebuffer)
  • Word length: 16-bit
  • Features: 3D polygon graphics, Gouraud shading, texture mapping, more sprites, quicker animation
  • Color palette: 32,768 colors
  • Double-buffered framebuffer with three modes:
    • 8bpp "packed pixel" mode: 256 simultaneous colors on screen; each pixel is an index into CRAM (can use full screen)
    • 16bpp "run length" mode: 256 simultaneous colors on screen; each pixel is both a number of pixels to display and the index of CRAM (limits screen size)
    • 16bpp "direct color" mode: 32,768 simultaneous colors on screen; each pixel is the color value (limits screen size)
  • VRAM: 256 KB, split into two 128 KB segments for each framebuffer. A priority system allows partial overlaying/underlaying of Mega Drive/Mega-CD graphics.
    • Sprites, polygons and textures accessed from 256 KB main SDRAM and 4–8 MB ROM cartridge.
  • Resolutions: 320×224, 320×240, 320×204 (direct color), 320×408 (8bpp)
    • Overscan: 450×262 (NTSC), 450×313 (PAL)
  • Refresh rate: 60 Hz (NTSC), 50 Hz (PAL)
    • Maximum frame rate: 60 FPS (NTSC), 50 FPS (PAL)
  • Framebuffer bandwidth: 72.727272 MB/s (36.363636 MB/s per framebuffer)
    • SH-2: 36.363636 MB/s (read/write, 1 byte/cycle per SH-2)
    • 32X VDP: 29.488906 MB/s (14.148 MB/s read, 15.340906 MB/s write)
    • 68000: 1.917613 MB/s (read/write, 4 cycles/byte)
  • Framebuffer fillrate: 18.181818 MPixels/s (16bpp), 36.363636 MPixels/s (8bpp)
    • SH-2: 18.181818 MPixels/s (16bpp), 36.363636 MPixels/s (8bpp)
    • 32X VDP: 7.670453 MPixels/s (16bpp), 15.340906 MPixels/s (8bpp)
    • 68000: 958,806 pixels/s (16bpp), 1.917613 MPixels/s (8bpp)
  • 3D polygon geometry calculations:
    • Polygon transformations: 260,000 polygons/sec
    • Lighting calculations: 230,000 polygons/sec (flat), 180,000 polygons/sec (Gouraud)
  • 3D polygon rendering:
    • Flat shading: 160,000 polygons/sec
    • Gouraud shading: 100,000 polygons/sec
    • Texture mapping: 50,000 polygons/sec
    • Texture Gouraud shading: 40,000 polygons/sec
  • 2D sprite/tile capabilities: Scrolling, scaling, rotation, alpha blending
    • Colors per sprite/tile: 128 (8bpp), 256 (8bpp), 8192 (16bpp), 32,768 (16bpp)
    • Tile size: 8×8 texels, 64 bytes (8bpp), 128 bytes (16bpp)
    • Sprite sizes: 8×8 to 320×240 texels, 64 bytes to 150 KB
    • Maximum sprites/tiles per frame: 3800 sprites/tiles (8bpp, 8×8, 237.5 KB), 1900 sprites/tiles (16bpp, 8×8, 237.5 KB)
    • Maximum sprites/tiles per scanline: 1463 texels, 182 sprites/tiles (8×8)
• Overlay/Underlay
  • Overlay/Underlay graphics processors:
    • Genesis VDP — 13.423294 MHz (NTSC), 13.300856 MHz (PAL), 8/16-bit data bus
    • Sega CD ASIC — 12.5 MHz, 32-bit (2x 16-bit) data bus
  • Overlay/Underlay Genesis VDP planes: 512–1536 color palette, 61–512 colors on screen
    • Sprite plane: 80 sprites/frame, 8×8 to 32×32 pixels/sprite, 16 colors/sprite, maximum 1280 sprite tiles/frame
    • Background planes: 2 tiled scrolling background layers, 8×8 pixels/tile, 16 colors/tile, 320×224 tilemaps, maximum 1808 tiles/frame
    • Fillrate: 6.934358 MPixels/s (read), 6.41376 MPixels/s (write), 6.934358–36.325644 MPixels/s (effective tile fillrate)
  • Overlay/Underlay Sega CD ASIC planes: Enhanced Mega Drive VDP planes, enhanced FMV plane
    • Sprite/Tile planes: 128–1536 colors on screen, sprite/tile scaling and rotation
    • FMV plane: Full motion video, 32,768 colors on screen
    • Fillrate: 6.934358 MPixels/s (read/write), 6.934358–36.325644 MPixels/s (effective tile fillrate)

• Sound
  • Sound chip: QSound PWM @ 23.01136 MHz (NTSC), 22.801467 MHz (PAL)[47]
    • Stereo PWM (Pulse Wave Modulation) mixing with Mega Drive sound; additional 2 channels (12 channels in total)
    • 11-bit PWM, stereo PCM output, surround sound

• Memory
  • System RAM: 648.5–1368.5 KB total, 512 KB (4 MBit) additional RAM to Mega Drive or Sega CD memory
    • Main RAM: 256 KB SDRAM
    • VRAM: 256 KB FPM DRAM (dual 128 KB framebuffers)
    • Genesis RAM: 136 KB (64 KB main, 64 KB video, 8 KB sound)
    • Sega CD RAM: 856 KB (512 KB main, 256 KB video, 64 KB audio)
  • RAM Clear Hardware: 512 bytes (used for flat-shaded polygons)
  • Internal processor cache: 5 KB
    • SH-2: 4 KB (2 KB per CPU)
    • 32X VDP: 1 KB, including 512 bytes (256 words) color palette RAM (CRAM)
  • Cartridge ROM: 4–8 MB

• Bandwidth
  • System RAM bandwidth: 118.749992 MB/s (NTSC), 118.330206 MB/s (PAL), 3 data buses, 48-bit data bus width
    • SDRAM: 46.02272 MB/s (NTSC, 16-bit, 23.01136 MHz, 43ns), 45.602934 MB/s (PAL, 16-bit, 22.801467 MHz, 43ns)
    • VRAM: 72.727272 MB/s (32-bit, 18.181818 MHz, 55 ns, 16-bit per framebuffer, 36.363636 MB/s per framebuffer, 55ns cycles, 80ns access)
  • Cartridge bandwidth:
    • Game ROM: 13.333333 MB/s (16-bit, 6.666666 MHz, 150 ns) to 28.571428 MB/s (16-bit, 14.285714 MHz, 70 ns)
    • Non-volatile SRAM: 6.666666 MB/s (6.666666 MHz, 150 ns) to 14.285714 MB/s (14.285714 MHz, 70 ns)
  • Internal processor cache bandwidth:
    • SH-2: 184.09088 MB/s (92.04544 MB/s per SH-2, 32-bit per SH-2)
    • 32X VDP: 92.04544 MB/s (32-bit, 23.01136 MHz), including 46.02272 MB/s (16-bit, 23.01136 MHz) color palette RAM

External Links

• Sega 32X on segaretro.org
• Wikipedia article on the 32X
• Dynamite Headdy on segaretro.org