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Sega 32X/Technical specifications

From Sega Retro

Back to: Sega 32X.

Technical specifications for the Sega 32X.

The following are upgrades over the Sega Mega Drive technical specifications.

See Sega Mega Drive technical specifications for details of the base Mega Drive hardware
  • System master clock rate: 53.693175 MHz (NTSC), 53.203424 MHz (PAL)[1]

CPU

  • Main CPU: Twin Hitachi SH-2 (SH7095) 32-bit RISC processors
  • Clock speed: 23.01136 MHz (NTSC), 22.801467 MHz (PAL)[1]
  • 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),[2] 1.3 MIPS per MHz,[3] 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:[4] 2x MULT multiplier DSP,[5][6][7] 2x DIVU division units,[5][6] parallel processing[8]
  • 2x MULT multiplier DSP: 46.022721 MOPS (NTSC, 23.01136 MOPS per SH-2), 45.602934 MOPS (PAL, 22.801467 MOPS per SH-2)[fn 1]
  • 2x DIVU division units: 16/32/64-bit division,[8] 1,180,069 divides/sec[fn 2]
  • 2x DMA units: 2x DMAC (Direct Memory Access Controller),[5] parallel processing[11]
  • Bus width: 64‑bit (2× 32‑bit) internal, 32‑bit external[12]
  • CPU co-processors: Overlay/Underlay processors
  • Motorola M68000 — 7.670453 MHz (NTSC), 7.600489 MHz (PAL),[1] 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)[13][1]
  • 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[14]
  • Color palette: 32,768 colors[15]
  • Double-buffered framebuffer with three modes:[16]
  • 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,[16] 320×204 (direct color),[17] 320×408 (8bpp)[18]
  • Overscan: 450×262 (NTSC), 450×313 (PAL)[19]
  • Refresh rate: 60 Hz (NTSC), 50 Hz (PAL)
  • Maximum frame rate: 60 FPS (NTSC), 50 FPS (PAL)
  • SH-2: 36.363636 MB/s (read/write, 1 byte/cycle per SH-2)[22]
  • 32X VDP: 29.488906 MB/s (14.148 MB/s read,[19] 15.340906 MB/s write)[23][24]
  • 68000: 1.917613 MB/s (read/write, 4 cycles/byte)[25]
  • SH-2: 18.181818 MPixels/s (16bpp),[22][21] 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:[fn 3]
  • Theoretical 3D polygon rendering performance, with both CPUs dedicated to graphics:
  • Practical 3D polygon rendering performance, with one CPU dedicated to graphics:
  • Flat shading: Up to 80,000 polygons/sec
  • Gouraud shading: Up to 50,000 polygons/sec
  • Texture mapping: Up to 25,000 polygons/sec
  • Texture Gouraud shading: Up to 20,000 polygons/sec
  • 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:
  • Mega Drive 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 Mega Drive 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)

Audio

  • Sound chip: QSound PWM @ 23.01136 MHz (NTSC), 22.801467 MHz (PAL)[36]
  • Stereo PWM (Pulse Wave Modulation) mixing with Mega Drive sound; additional 2 channels (12 channels in total)
  • 11-bit PWM, stereo PCM output,[15] surround sound

Memory

  • System RAM: 648.5–1368.5 KB total, 512 KB (4 MBit) additional RAM to Mega Drive or Sega CD memory[14]
  • Main RAM: 256 KB SDRAM
  • VRAM: 256 KB FPM DRAM (dual 128 KB framebuffers)[36]
  • Mega Drive 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)[22]
  • Internal processor cache: 5 KB
  • SH-2: 4 KB (2 KB per CPU)[14]
  • 32X VDP: 1 KB,[37] including 512 bytes (256 words) color palette RAM (CRAM)[38]

Bandwidth

  • System RAM bandwidth: 118.749992 MB/s (NTSC), 118.330206 MB/s (PAL), 3 data buses, 48-bit data bus width[13][21]
  • SDRAM: 46.02272 MB/s (NTSC, 16-bit, 23.01136 MHz, 43ns), 45.602934 MB/s (PAL, 16-bit, 22.801467 MHz, 43ns)[40][41]
  • 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)[42][20]
  • 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[43]

Storage

  • Cartridge: Compatible with all Mega Drive models, JVC Wondermega can store save game/score information.
  • CD-ROM: If you have a Sega Mega-CD; speed same as Sega Mega-CD compatible with audio CD, CD&G, SegaCD and JVC WonderMega

Input/Output

  • I/O: Same as Mega Drive; 32X upgradable; can upgrade the 32X

Notes

  1. 1 operation per cycle[9]
  2. 39 cycles per divide[10]
  3. 46,022,720 DSP operations/sec, 1,180,069 DIVU divides/sec
  4. 96 adds/multiplies and 9 divides per polygon:[27]
    • 131,118 polygons/sec: 12,587,328 DSP operations, 1,180,069 DIVU divides
    • 134,397 polygons/sec: 32,255,280 SH-2 cycles (96 adds/multiplies, 144 divide cycles)[10]
  5. 128 adds/multiplies and 9 divides per polygon:[27]
    • 131,118 polygons/sec: 16,783,104 DSP operations, 1,180,069 DIVU divides
    • 103,160 polygons/sec: 28,059,520 SH-2 cycles (128 adds/multiplies, 144 divide cycles)
  6. 192 adds/multiplies and 9 divides per polygon:[27]
    • 131,118 polygons/sec: 25,174,656 SH-2 DSP operations, 1,180,069 DIVU divides
    • 58,535 polygons/sec: 19,667,760 SH-2 cycles (192 adds/multiplies, 144 divide cycles)
  7. 46,022,720 SH-2 cycles/ops per sec (23.01136 MHz per SH-2), 1,180,069 DIVU divides/sec, 23.01136 MHz 32X VDP
    • SH-2: 215 cycles (128 geometry adds/multiplies, 30 SDRAM cycles for 40 bytes,[28] 30 raster ops,[29][30] 27 cycles 32X VDP command)[23] and 9 divides per polygon, 1 add per pixel,[31] 247 cycles and 9 divides per 32-pixel polygon:
    • 131,118 polygons/sec: 32,386,146 SH-2 cycles, 1,180,069 DIVU divides
    • 31,858 polygons/sec: 12,456,478 SH-2 cycles (247 cycles, 144 divide cycles)
    • 32X VDP: 7 cycles/poly, 3 cycles/pixel (16bpp),[23][24] 1.5 cycles/pixel (8bpp),[18] 103 cycles per 32-pixel 16bpp polygon, 55 cycles per 32-pixel 8bpp polygon
  8. 252 cycles (192 geometry adds/multiplies,[27] 30 SDRAM cycles, 30 raster ops) and 9 divides per polygon, 3 operations/scanline per polygon,[30][21] 264 cycles and 9 divides per 4-scanline polygon
    • 16bpp: 3 cycles per pixel, 369 SH-2 cycles and 9 DIVU divides per 32-pixel polygon
  9. Texture mapping:
    • Flat shading: 188 SH-2 cycles (128 geometry adds/multiplies, 30 SDRAM cycles for 40 bytes,[28] 30 raster ops)[29][30] and 9 divides per polygon, 1 add per pixel,[31] 220 SH-2 cycles and 9 divides per 32-pixel polygon
    • Texture mapping: 132 SH-2 cycles and 41 divides per 32-texel polygon
    • 132 SH-2 cycles per 32-texel texture: 2 block moves, 2 cycles per texel (2 bytes per texel), 2 cycles access
    • 41 divides per 32-texel polygon, 9 divides per polygon, 32 divides per 32-texel polygon (1 divide per texel)[33]
    • Texture mapping: 352 SH-2 cycles and 50 divides per 32-texel polygon
    • 23,601 polygons/sec: 9,487,602 SH-2 cycles, 1,180,069 DIVU divides
    • 31,714 polygons/sec: 36,535,118 SH-2 cycles (1152 cycles per polygon)
  10. Texture Gouraud shading:
    • Gouraud shading: 369 SH-2 cycles and 9 divides per 32-pixel polygon
    • Texture mapping: 132 SH-2 cycles and 41 divides per 32-texel polygon
    • Texture Gouraud shading: 501 SH-2 cycles and 50 divides per 32-texel polygon
    • 23,601 polygons/sec: 11,824,101 SH-2 cycles, 1,180,069 DIVU divides
    • 25,379 polygons/sec: 33,018,079 SH-2 cycles (1301 cycles per polygon)

References

  1. 1.0 1.1 1.2 1.3 File:32XUSHardwareManual.pdf, page 54
  2. File:Hitachi SuperH Programming Manual.pdf, page 390
  3. File:SH-2A.pdf, page 2
  4. File:Sega Service Manual - Sega Saturn (PAL) - 013-1 - June 1995.pdf
  5. 5.0 5.1 5.2 File:SH7604 Hardware Manual.pdf, page 3
  6. 6.0 6.1 File:SH7604 Hardware Manual.pdf, page 22
  7. File:ST-103-R1-040194.pdf, page 23
  8. 8.0 8.1 File:SH7604 Hardware Manual.pdf, page 303
  9. File:Hitachi SuperH Programming Manual.pdf, page 31
  10. 10.0 10.1 File:Hitachi SuperH Programming Manual.pdf, page 155
  11. File:SH7604 Hardware Manual.pdf, page 219
  12. File:ST-103-R1-040194.pdf
  13. 13.0 13.1 File:Genesis32XUSManual.pdf, page 7
  14. 14.0 14.1 14.2 File:Genesis32XUSOverview.pdf
  15. 15.0 15.1 File:32XUSHardwareManual.pdf
  16. 16.0 16.1 File:Genesis32XUSOverview.pdf, page 7
  17. File:32XUSHardwareManual.pdf, page 49
  18. 18.0 18.1 18.2 File:32XUSHardwareManual.pdf, page 50
  19. 19.0 19.1 File:32XUSHardwareManual.pdf, page 55
  20. 20.0 20.1 File:TC511664B datasheet.pdf
  21. 21.0 21.1 21.2 21.3 21.4 21.5 File:32XUSHardwareManual.pdf, page 76
  22. 22.0 22.1 22.2 File:Genesis32XUSOverview.pdf, page 9
  23. 23.0 23.1 23.2 File:32XUSHardwareManual.pdf, page 53
  24. 24.0 24.1 File:Genesis32XUSOverview.pdf, page 51
  25. File:Genesis32XUSOverview.pdf, page 53
  26. File:32XUSHardwareManual.pdf, page 42
  27. 27.0 27.1 27.2 27.3 Design of Digital Systems and Devices (pages 95-97)
  28. 28.0 28.1 File:32XUSHardwareManual.pdf, page 77
  29. 29.0 29.1 Algorithms for Parallel Polygon Rendering (pages 33-36)
  30. 30.0 30.1 30.2 Transformation Of Rendering Algorithms For Hardware Implementation (page 53)
  31. 31.0 31.1 Algorithms for Parallel Polygon Rendering (page 35)
  32. Service Games: The Rise and Fall of SEGA, page 154
  33. State of the Art in Computer Graphics: Visualization and Modeling (page 110)
  34. File:32XUSHardwareManual.pdf, page 51
  35. Sprite engine for the Sega 32X
  36. 36.0 36.1 File:Genesis32XUSManual.pdf
  37. File:32XUSHardwareManual.pdf, page 41
  38. File:32XUSHardwareManual, page 13
  39. 39.0 39.1 Dr. DevSter's Guide to The Sega 32X
  40. File:Genesis32XUSManual.pdf, page 17
  41. File:UPD4504161 datasheet.pdf
  42. File:Genesis32XUSManual.pdf, page 22
  43. File:Genesis32XUSManual, page 7