Sega 32X/Technical specifications

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Technical specifications for the Sega Master System.

  • 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
    • Mega Drive CPU:
      • 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)
  • Framebuffer bandwidth: 72.727272 MB/s (36.363636 MB/s per framebuffer)[20][21]
    • 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]
  • Framebuffer fillrate: 18.181818 MPixels/s (16bpp), 36.363636 MPixels/s (8bpp)[18][26]
    • 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]
  • 3D polygon rendering:
  • 2D sprite/tile capabilities: Scrolling,[34] scaling, rotation, alpha blending[35][21]
    • 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]
  • Cartridge ROM: 4–8 MB[39]

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]
  • Cartridge bandwidth:[39][21]
    • 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] 1 operation per cycle[9]]
  2. ↑ [39 cycles per divide[10] 39 cycles per divide[10]]
  3. ↑ [46,022,720 DSP operations/sec, 1,180,069 DIVU divides/sec 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]
    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)
    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)
    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
    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
    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) 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) 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
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