Sega System 16

From Sega Retro

System16a motherboard.jpg
Sega System 16
Manufacturer: Sega Enterprises, Ltd.
Variants: Pre-System 16, System 16A, System 16B, System 18, System C
Release Date RRP Code
Arcade
World		 ? ?





































The Sega System 16 (セガ システム 16) is an arcade board released by Sega in 1985 as a 16‑bit successor to the Sega System 1 and Sega System 2. Throughout its lifespan, there would be around forty games released on this hardware, making it one of Sega's most successful hardware designs. It was produced in three variants: the Pre-System 16 (1985), System 16A (1986), and System 16B (1987). The only difference between the Pre-System 16 and System 16A are clock speeds, while the System 16B has improved graphics, sound and memory.

The System 16 is the home to many of Sega's most successful franchises, including Shinobi, Fantasy Zone, Altered Beast and Golden Axe. Following the Sega Hang-On hardware, the System 16 popularised the use of the Motorola 68000 and Zilog Z80 combo, which was later imitated for Capcom's successful CPS-1 and CPS-2 boards (among other arcade systems of the day), as well as the Sega Mega Drive and Neo Geo consoles.

In order to prevent piracy, as well as illegal bootleg games, many System 16 boards used an encryption system. A Hitachi FD1094 chip, containing the main CPU as well as the decryption key, was used in place of a regular CPU.

Though Pre-System 16, System 16A and System 16B are the three most recognised variants of the hardware, there is technically a fourth, dubbed "System 16C", which was used by the 2008 release of Fantasy Zone II DX: The Tears of Opa-Opa. Although Fantasy Zone II DX arrived almost a decade and a half after the System 16 hardware was discontinued, its real arcade release means that System 16C specifications may belong to the Sega System 16 series. Fantasy Zone II DX needs more RAM than any of the previous System 16 boards can offer, but otherwise adheres to their limitations.

Technical specifications

System 16 specifications

  • Board Composition: CPU Board, Video Board
  • CPU:
  • MCU:
  • Main MCU: Intel i8751 @ 8 MHz (8‑bit instructions @ 8 MIPS, 1 instruction per cycle)
  • Sound MCU: Intel i8048 @ 6 MHz (8‑bit instructions @ 6 MIPS, 1 instruction per cycle)
  • Sound Chips:
  • FM Sound Chip: Yamaha YM2151 @ 4 MHz (8 FM synthesis channels)
  • PCM Sound Chip: NEC μPD7751 ADPCM Decoder @ 6 MHz[1]
  • ADPCM Sampling Channels: 3
  • Audio Bit Depth: 8‑bit
  • GPU Chipset: 315‑5011 sprite line comparator, 315‑5012 sprite generator, 2× 315‑5049 tilemap chips, 315‑5107 & 315‑5108 display timers, 315‑5143 & 315‑5144 sprite chips, 315‑5149 video mixer[2]
  • Clock Rate Performance: 12.5874 MHz sprite line buffer render clock, 6.2937 MHz sprite line buffer scan/erase & pixel clock
  • Memory: Up to 1252 KB (304 KB main, 801 KB video, 163 KB sound)
  • RAM: 147 KB, including 77 KB high-speed SRAM (Static RAM)[1][3]
  • Main RAM: 48 KB (16 KB work RAM, 16 KB I/O, 16 KB NVRAM)
  • Video RAM: 97 KB
  • CPU Board: 42 KB (32 KB tiles, 4 KB text, 2 KB sprites, 4 KB color, 16 KB I/O, 16 KB NVRAM)
  • Video Board: 55 KB SRAM (2 KB line buffers)
  • Sound RAM: 2 KB
  • ROM: Up to 1121 KB EPROM (1121 KB (256 KB main, 704 KB video, 161 KB sound)
  • Horizontal: 320×224 (display), 342×262 (overscan)[1]
  • Vertical: 224×320 (display), 262×342 (overscan)
  • Scanlines: 224 (display), 262 (overscan), progressive scan
  • Line buffer resolution: 512 pixels
  • 15-bit RGB high color depth (32,768 colors), 1‑bit shadow & highlight triples up to 98,304 colors[4][5]
  • Colors on Screen: 4096 (unique colors) to 6144 (with shadow & highlight)[1]
  • Graphical Planes:
  • 1 sprite layer
  • 1 text layer
  • 2 tile layers (row & column scrolling,[4] 8×8 tiles)[1]
  • Sprite Capabilities: Dual line buffers, double buffering, 128 on‑screen sprites[4][3]
  • Fillrate per Scanline: 800 sprite pixels/texels (800.75 sprite processing ticks) per scanline
  • Sprites per Scanline: 100 sprites per scanline
  • Colors per Sprite: 16
  • Sprite Sizes: 8 to 256 pixels width, 8 to 256 pixels height[1]

System 16B specifications

System 16B featured the following upgrades:[6][4]

  • Board composition: CPU Board, ROM Board
  • Sound CPU: Zilog Z80 @ 5 MHz (8/16‑bit instructions @ 0.725 MIPS)
  • PCM Sound Chip: NEC μPD7759 ADPCM Decoder @ 640 kHz[7]
  • ADPCM Sampling Channels: 1
  • Audio Bit Depth: 9‑bit[8]
  • Other Features: 8 kHz sampling rate, up to 128 KB audio ROM, up to 256 samples, speech synthesizer
  • GPU Chipset: 315‑5196 sprite generator, 315‑5197 tilemap generator, 315‑5213 sprite chip, 315‑5248 & 315‑5250 math chips[2]
  • Sprite Capabilities: Sprite scaling
  • Memory: Up to 3675 KB (667 KB main, 2913 KB video, 194 KB sound)
  • RAM: 147 KB, including 104 KB high-speed SRAM (Static RAM)
  • Main RAM: 48 KB (16 KB work SRAM, 16 KB I/O, 16 KB NVRAM)
  • Video RAM: 97 KB, including 84 KB SRAM (4 KB sprites, 4 KB color, 64 KB tiles, 4 KB text, 8 KB line buffers)
  • Sound RAM: 2 KB SRAM
  • SRAM performance: 22.222222 MHz (45 ns)[9]
  • ROM: Up to 3528 KB (520 KB main, 2816 KB video, 192 KB sound)

System 16C specifications

System 16C featured the following upgrade over System 16B in 2008:[6]

  • RAM: 387 KB, including 104 KB high-speed SRAM (Static RAM)
  • Main RAM: 288 KB (256 KB work RAM, 16 KB I/O, 16 KB NVRAM)
  • Video RAM: 97 KB, including 84 KB SRAM (4 KB sprites, 4 KB color, 64 KB tiles, 4 KB text, 8 KB line buffers)
  • Sound RAM: 2 KB SRAM

List of games

Pre-System 16

System 16A

System 16B

System 16C

Production credits

Source:
Developer mentions[10]


Magazine articles

Main article: Sega System 16/Magazine articles.

Photo gallery

Pre-System 16

  • Motherboard

Sega System 16A

  • Motherboard (side 1)

  • Motherboard (side 2)

Sega System 16B

  • Motherboard

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Sega Pre-System 16 & System 16A Hardware (MAME)
  2. ↑ 2.0 2.1 Sega 16‑Bit common hardware (MAME)
  3. ↑ 3.0 3.1 Sega Pre-System 16 hardware notes (2004-03-29)
  4. ↑ 4.0 4.1 4.2 4.3 Sega System 16B hardware notes (2003-01-12)
  5. ↑ Sega "X-Board" hardware notes (2004-12-03)
  6. ↑ 6.0 6.1 Sega System 16B Hardware (MAME)
  7. ↑ File:UPD7759 datasheet.pdf
  8. ↑ NEC UPD7759 ADPCM Speech Processor (MAME)
  9. ↑ File:TMM2018 datasheet.pdf
  10. ↑ File:SS16CSTV2 Album JP Booklet.pdf, page 5


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