Sega Master System/Technical specifications

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Back to: Sega Master System.

Technical specifications for the Sega Master System.

  • System master clock rate: 53.693175 MHz (NTSC), 53.203424 MHz (PAL)[1][2]
  • Master clock cycles per frame: 896,040 (NTSC), 1,070,460 (PAL)[2]
  • Master clock cycles per scanline: 3420[2]

CPU

  • Clock rate: 3.579545 MHz (NTSC), 3.54689493 MHz (PAL/SECAM)[n 1]
  • The Z80 directly addresses program RAM and ROM, but only addresses VRAM through VDP hardware ports.[1] It can access VRAM by commanding/programming VDP.[4]
  • Instruction set: 8‑bit and 16‑bit instructions, 6–18 registers[5]
  • Bus width: 8‑bit

Graphics

  • Revisions: Sega 315‑5124 / Yamaha YM2602 (Mark III, Master System), Sega 315‑5246 / NEC UPD9004G (Master System II)
  • Note: An evolution of the TMS9918
  • Clock rate: 10.738635 MHz (NTSC),[7] 10.640685 MHz (PAL)[8]
  • Pixel clock rate: 5.3693175 MHz (NTSC), 5.3203424 MHz (PAL)[9]
  • Bus width: 16‑bit[n 2]
  • Memory bus clock rate: 5.3693175 MHz (NTSC), 5.3203424 MHz (PAL)
  • Registers: 8‑bit and 16‑bit[10][4]
  • Memory access: VDP directly addresses VRAM, has its own internal CRAM and sprite line buffer, and has access to cartridge ROM. It can be commanded and programmed by Z80.
  • Color burst clock input: 3.579545 MHz (NTSC),[3] 3.546895 MHz (PAL)
  • Screen resolutions: 256x192 and 256x224. PAL/SECAM also supports 256x240.
  • Overscan resolution: 342x262 (NTSC), 342x313 (PAL)[4]
  • Scanlines: 262 (NTSC), 313 (PAL)
  • Refresh rate: 59.922743 Hz (NTSC), 49.701459 Hz (PAL)[15]
  • Maximum frame rate: 59.922743 frames/sec (NTSC), 49.701459 frames/sec (PAL)
  • Colors: Up to 32 simultaneous colors (16 for sprites, 16 for background) available from a palette of 64 colors (6‑bit RGB), 16 colors (4‑bit) per pixel/tile/sprite
  • Programmable capabilities: Mid‑frame palette swap allows up to 64 simultaneous colors, 105 color palette (all on screen) possible with static image,[16] integer sprite zooming[17] (up to 32×32 pixels)[18]
  • VDP display modes:[4]
  • Modes 1–2: 256x192 resolution, tilemap, 2 colors per tile, SG-1000 backwards compatibility
  • Mode 3: 64×48 resolution, bitmap, 16 colors per pixel, SG-1000 backwards compatibility
  • Mode 4: 256x192, 256x224 and 256x240 resolutions, tilemap, 16 colors per tile, used by most Master System games
  • VRAM bandwidth:
  • VDP read bandwidth: 7.692306 MB/s
  • Z80 write bandwidth: 298.295 KB/s (NTSC), 295.574 KB/s (PAL)[n 3]
  • Z80 write during active display: 174.794 KB/s (NTSC), 181.112 KB/s (PAL)[20]
  • Read fillrate: 5.369317 MPixels/s (NTSC), 5.320342 MPixels/s (PAL)
  • Mode 3-4 write fillrate: 4-bit per pixel, 596,590 pixels/s (NTSC), 591,148 pixels/s (PAL)
  • Mode 3-4 write during active display: 349,588 pixels/s (NTSC), 362,224 pixels/s (PAL)
  • Mode 1-2 write fillrate: 1-bit per pixel, 2.386363 MPixels/s (NTSC), 2.364595 MPixels/s (PAL)
  • Mode 1-2 write during active display: 1.398352 MPixels/s (NTSC), 1.448896 MPixels/s (PAL)
  • Tile read fillrate: 83,895 tiles/sec (NTSC), 83,130 tiles/sec (PAL)

Mode 4

  • Characters/Tiles: 8x8 pixel characters/tiles, 16 colors per tile, maximum 488 unique characters/tiles on screen (due to VRAM space limitation), horizontal & vertical background tile flipping (up to 1792 flipped tiles in VRAM)
  • Background: Tilemap playfield, 8x8 tiles, horizontal & vertical tile flipping, up to 448 tiles/patterns in VRAM used by background,[21] up to 1792 flipped tiles in VRAM used by background, definable priorities for individual background tiles[4]
  • Sprites: 16 colors (15 opaque, 1 transparent) per sprite, up to 256 tiles/patterns in VRAM used by sprites,[4] collision detection[22]
  • Sprite pixel sizes: 8x8, 8x16
  • Sprite zoom pixel sizes: 16x16, 16x32
  • Sprite line buffer: VDP contains internal sprite line buffer for 8 sprites per scanline, double buffering, prevents delay while VDP reads VRAM, sprite priority determined by order of sprites in buffer[4]
  • Sprites on screen: 64 sprites on screen, more than 64 sprites with mid-screen raster effects[23]
  • Sprites per scanline: 8 sprites (non-flickering) per scanline, 9 flickering sprites per scanline[24]
  • Scrolling: Smooth hardware scrolling, horizontal & vertical scrolling, diagonal scrolling, line scrolling, partial screen scrolling[25]
  • IRQ raster interrupt capabilities:[25] Interrupt per frame, interrupt per scanline,[4] mid‑frame palette swap, transparency effect, line scrolling, partial screen scrolling
  • VRAM screen map: 2 KB to 2.25 KB[21]
  • Sprite attribute table: 256 bytes (2 Kbits), including 64 byte tile/pattern data
  • Background name table: 1.75 KB (14 Kbits) or 2 KB (16 Kbits)[4][n 4]
  • Tile write fillrate: 32 bytes per tile, 9321 tiles/sec (NTSC), 9236 tiles/sec (PAL)
  • Write during active display: 5462 tiles/sec (NTSC), 5659 tiles/sec (PAL)

Modes 1-2

See SG-1000 specifications for more details
  • Tiles: 832-1024 tiles,[n 5] 2 colors per tile, 8 bytes per tile
  • Sprites: 32-64 sprites, 64-256 sprite tiles
  • Sprite pixel sizes: 8x8, 16x16
  • Sprite zoom pixel sizes: 16x16, 32x32
  • Tile write fillrate: 8 bytes per tile, 37,286 tiles/sec (NTSC), 36,946 tiles/sec (PAL)
  • Write during active display: 21,849 tiles/sec (NTSC), 22,639 tiles/sec (PAL)
  • Additional Master System capabilities: Raster effects, programmable full screen zooming[26]

Audio

  • 4 channel mono sound[25]
  • 3 square wave sound generator tone channels: 4–10 octaves, 16 volume levels, 1024 (10‑bit) frequencies, 122 Hz to 125 kHz frequency range
  • 1 noise generator channel: White noise, periodic noise, 16‑bit LSFR, 16‑bit ring buffer, 3 preset frequencies (7.8 to 19.5 kHz), can match frequency of 3rd tone channel
  • PCM/PWM sampling: Uses 1-3 tone channels to produce a single PCM channel, 1‑bit to 12‑bit audio depth, 4 kHz to 44.1 kHz sampling rate,[27][28] up to 176.4 kbps (22.05 KB/s) bitrate[29][30]
  • Clone of the SN76489 with different noise LFSR and frequency counter implementations
  • 9 mono FM synthesis channels
  • 2‑operator FM synthesis sound
  • Instruments: 15 pre‑defined instruments and user‑defined sound
  • Rhythm mode: 3 channels can be used for percussion sounds
  • Built into Japanese Master System
  • Available as plug‑in module for Mark III
  • Supported by certain games only

Memory

  • System RAM: 24 KB (most models) or 40 KB (some models)[31][3]
  • Main/Program RAM: 8 KB (64 Kbits)
  • Note: Since Z80 reads program code directly from ROM, program RAM is primarily used for general program data (such as state information).[32]
  • VRAM: 16 KB (128 Kbits, most models) or 32 KB (256 Kbits, some models)[14]
  • Color RAM (CRAM): 32 bytes (256 bits, 32x 8-bit entries)
  • Sprite line buffer: 32 bytes (256 bits, 8x 32-bit entries)
  • Note: Z80 can read program code directly from ROM, allowing program RAM to be used for general program data (such as state information).
  • Cartridge battery backup SRAM: 8 KB (64 Kbits) to 32 KB (256 Kbits)[33]

Configuration

  • Z80, VDP <‑> Main RAM, System ROM, Cartridge ROM (8‑bit)
  • VDP <‑> VRAM (16‑bit)
  • Main RAM: 8‑bit, XRAM/SRAM, 3.579545 MHz (NTSC) or 3.546894 MHz (PAL)[n 6]
  • VRAM: 16‑bit (2x 8‑bit), XRAM/PSRAM, 3.846153 MHz[n 7]
  • ROM chips: 8‑bit, 3.579545 MHz (NTSC) or 3.546894 MHz (PAL)[n 8]

Bandwidth

  • System RAM bandwidth: 11 MB/s[n 9]
  • Main RAM: 3.579545 MB/s (NTSC), 3.546894 MB/s (PAL)[n 10]
  • VRAM: 7.692306 MB/s[n 11]
  • ROM bandwidth: 3.5 MB/s[n 10]
  • Internal processor bandwidth:
  • Z80: 3.579545 MB/s (NTSC), 3.546894 MB/s (PAL)[n 12]
  • VDP: 10 MB/s[n 13]
  • CRAM: 5.3693175 MB/s (NTSC), 5.3203424 MB/s (PAL)[n 12]
  • Sprite line buffer: 5.3693175 MB/s (NTSC), 5.3203424 MB/s (PAL)[n 12]

Notes

  1. [CPU clock cycles per frame: 59,736 (NTSC), 71,364 (PAL)
    CPU clock cycles per scanline: 228 CPU clock cycles per frame: 59,736 (NTSC), 71,364 (PAL)
    CPU clock cycles per scanline: 228]
  2. [16‑bit VRAM bus, 8‑bit Z80/ROM bus 16‑bit VRAM bus, 8‑bit Z80/ROM bus]
  3. [Byte per 12 cycles[19] Byte per 12 cycles[19]]
  4. [16‑bit per tile[25]
    • 256x192 resolution: 1.75 KB, 32x28 table (256x224 pixels), 896 tiles (768 visible)
    • 256x224 resolution: 2 KB, 32x32 table (256x256 pixels), 1024 tiles (896 visible)
    • 256x240 resolution: 2 KB, 32x32 table (256x256 pixels), 1024 tiles (960 visible)
    16‑bit per tile[25]
    • 256x192 resolution: 1.75 KB, 32x28 table (256x224 pixels), 896 tiles (768 visible)
    • 256x224 resolution: 2 KB, 32x32 table (256x256 pixels), 1024 tiles (896 visible)
    • 256x240 resolution: 2 KB, 32x32 table (256x256 pixels), 1024 tiles (960 visible)]
  5. [768 background tiles, 64-256 sprite tiles 768 background tiles, 64-256 sprite tiles]
  6. [279/281 ns[34][35] 279/281 ns[34][35]]
  7. [260 ns[34][36] 260 ns[34][36]]
  8. [279/281 ns 279/281 ns]
  9. [2 buses (24-bit bus width) 2 buses (24-bit bus width)]
  10. 10.0 10.1 [8-bit bus 8-bit bus]
  11. [16-bit bus 16-bit bus]
  12. 12.0 12.1 12.2 [8-bit 8-bit]
  13. [16-bit 16-bit]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 File:SMSServiceManualEU.pdf
  2. 2.0 2.1 2.2 https://github.com/ekeeke/Genesis-Plus-GX/blob/master/core/system.h
  3. 3.0 3.1 3.2 3.3 3.4 Sega Mark-III Hardware Notes (2008-11-14)
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 Sega Master System VDP documentation (2002-11-12)
  5. 5.0 5.1 Obsolete Microprocessors
  6. 6.0 6.1 6.2 File:SMS2ServiceManualEU.pdf
  7. File:SMSServiceManualEU.pdf, page 4
  8. File:SMSServiceManualEU.pdf, page 14
  9. https://github.com/mamedev/mame/blob/master/src/mame/drivers/sms.cpp
  10. File:SoftwareReferenceManualForSegaMarkIIIEU.pdf
  11. File:CXA1145P datasheet.pdf
  12. File:MB3514 datasheet.pdf
  13. Sega Master System Video Output
  14. 14.0 14.1 14.2 Sega Master System Documents
  15. Genesis Plus
  16. TMS9918 test (AtariAge)
  17. Sega Master System VDP Documentation
  18. New sprite record (MSX Research Center)
  19. File:SC-3000ServiceManual.pdf, page 12
  20. Bytes written to VRAM per frame
  21. 21.0 21.1 File:SoftwareReferenceManualForSegaMarkIIIEU.pdf, page 8
  22. File:SoftwareReferenceManualForSegaMarkIIIEU.pdf, page 6
  23. Displaying more than 32 colours - raster effect (SMS Power)
  24. Coleco graphics capacity (AtariAge)
  25. 25.0 25.1 25.2 25.3 25.4 Sega Master System Technical Documentation (1998-06-10)
  26. Fun with zooming (SMS Power)
  27. 27.0 27.1 Sega SN76489
  28. pcmenc: Advanced PCM encoder for 8-bit sound chips
  29. High-quality PCM with pcmenc
  30. Sega Master System high-fidelity audio
  31. 31.0 31.1 Sega Master System RAM
  32. 32.0 32.1 SMSARCH: A Sega Master System Cartridge Archiver
  33. Sega Mappers
  34. 34.0 34.1 File:UPD4168 datasheet.pdf
  35. File:KM6264B datasheet.pdf
  36. File:HM65256B datasheet.pdf
  37. File:CXK3864 datasheet.pdf
  38. ROM Part Numbers
  39. File:MB831000 datasheet.pdf
  40. Memory Mapper Hardware Notes
  41. SMS PINOUTs
  42. File:TMS27C512 datasheet.pdf
  43. File:AM29F040 datasheet.pdf


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