Sega System 1

From Sega Retro

System1 PCB1.jpg
Sega System 1
Manufacturer: Sega
Release Date RRP Code

The Sega System 1 is an arcade platform officially debuted by Sega in 1983,[1] based on earlier 1982 prototype hardware. It is a Z80-based platform and the first in the decade-long "System" series of arcade boards.

The System 1 was a relatively popular arcade board for its day, supported not only by Sega, but by Japanese developers Coreland and VIC Tokai between 1983 and 1987. In 1985 it was succeeded by the slightly more powerful Sega System 2 board, though new games were released for both systems concurrently. Many of the System 1's games were ported to the SG-1000 and Sega Master System consoles.

Specifications

System 1

  • Board composition: One board
    • Master clock rate: 19.99982 MHz[2]
  • Main CPU: Zilog Z80 @ 4 MHz (8/16-bit instructions, 0.58 MIPS)
  • Sound CPU: Zilog Z80 @ 4 MHz (8/16-bit instructions, 0.58 MIPS)
  • Sound chips: Sega SN76496 @ 4 MHz, Sega SN76496 @ 2 MHz
  • MCU: Intel 8751[2]

Graphics

  • Graphics chipset:[2]
    • Sega 315-5011 sprite line comparator: 16‑bit line buffer RAM (14.999865 MHz, 29.99973 MB/s),[3][4] 9.99991 MHz sprite line buffer render/pixel clock, 4.999955 MHz sprite line buffer scan/erase clock[2][5]
    • Sega 315-5012 sprite generator
    • Sega 315-5049 tilemap generator
  • Video resolution: 256×224 (active), 640×260 (overscan)[2]
    • Scanlines: 260 (224 active, 36 VBlank)
    • Pixel clock rate: 9.99991 MHz (3.446099 MHz active, 6.55381 MHz HBlank/VBlank)
    • Refresh rate: 60.0952 Hz (VSync)
  • Color palette: 4096[6]
    • Colors on screen: 2048[2]
  • Sprite plane: Line buffer, double buffering, 16 colors per sprite, sprite flipping, hardware collision detection[6][2]
    • Sprites on screen: 128 sprites (2 KB sprite attributes, 16 bytes per sprite)[5]
    • Sprite sizes: 8×8 to 256×224 texels
    • Line buffer fillrate: 9.99991 MPixels/s
    • Sprites per scanline: 32 sprites, 640 texels
  • Background planes: 2 tilemap layers (1 static, 1 scrolling), 8×8 tiles[6][2]
    • Tilemap sizes: 256×256 for both planes

Memory

  • Memory: 155.75 KB (52 KB main, 93.75 KB video, 10 KB sound)
  • RAM: 19.5 KB[2]
    • Main: 4 KB (8-bit, 4 MHz, 4 MB/s)[7]
    • Video: 13.5 KB SRAM (4 KB video, 2 KB sprite attributes, 1.5 KB sprite line buffers,[6][5] 2 KB palette, 4 KB collision)
    • Sound: 2 KB
  • ROM: 136.25 KB[8]
    • Main: 48 KB
    • Video: 80.25 KB (48 KB tiles, 32 KB sprites, 256 bytes palette)
    • Sound: 8 KB

Prototype

Super Locomotive in 1982 ran on prototype arcade hardware that was very similar to the Sega System 1 later released in 1983. Super Locomotive had largely identical specifications, but with the following differences:[9][10][11]

Graphics

  • Graphics chipset:
    • Sega 315-5011 sprite line comparator: 16‑bit line buffer RAM (11.79648 MHz, 23.59296 MB/s), 7.86432 MHz sprite line buffer render clock, 3.93216 MHz sprite line buffer scan/erase/pixel clock[5]
  • Video resolution: 248×224 (active), 256×256 (overscan)
    • Pixel clock rate: 3.93216 MHz
    • Refresh rate: 60 Hz
  • Color palette: 1568
    • Colors on screen: 768
  • Sprite plane:
    • Sprites on screen: 32 sprites (512 bytes sprite attributes, 16 bytes per sprite), 64 sprites with raster interrupt
    • Sprite sizes: 8×8 to 248×224 texels
    • Line buffer fillrate: 7.86432 MPixels/s
    • Sprites per scanline: 32 sprites, 512 texels

Memory

  • Memory: 113.3125 KB (50 KB main, 53.3125 KB video, 10 KB sound)
  • RAM: 7.78125 KB
    • Main: 2 KB
    • Video: 3.78125 KB SRAM (1.75 KB video, 512 bytes sprite atttributes, 1.5 KB sprite line buffers, 32 bytes scrolling)
    • Sound: 2 KB
  • ROM: 105.53125 KB[12]
    • Main: 48 KB
    • Video: 49.53125 KB (48 KB graphics, 1.53125 KB palette)
    • Sound: 8 KB

Gallery

  • PCB 1

  • PCB 2

List of Games

References

  1. ↑ 1983 Timeline (Sega Corporation)
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Sega System 1 / System 2 (MAME)
  3. ↑ File:Regulus System1 US Manual.pdf, page 8
  4. ↑ File:HangOn Schematics.pdf, page 4
  5. ↑ 5.0 5.1 5.2 5.3 Sega Pre-System 16 hardware notes (2004-03-29)
  6. ↑ 6.0 6.1 6.2 6.3 System1 / System 2 video hardware (MAME)
  7. ↑ File:Regulus System1 US Manual.pdf, page 14
  8. ↑ Star Jacker (MAME)
  9. ↑ Super Locomotive (MAME)
  10. ↑ Super Locomotive video hardware (MAME)
  11. ↑ Sega Z80 Based Hardware (System 16)
  12. ↑ Super Locomotive (MAME)


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