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NES

• Nintendo
• Entertainment
• System

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GAME CONSOLE

• 62 millions sold
• about 50 clones
• various plugins
  • midi
  • floppy disk
  • modem

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OVERVIEW

• cpu
• memory
• graphics
• sound
• controllers

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PART 1

• CPU
• memory
• graphics
• sound
• controllers

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RICOH 2A03/2A07

• ricoh 2a03 cpu

• 2a03 - ntsc

• 2a07 - pal

• 1,66 MHz PAL
• 1,79 MHz NTSC

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RICOH 2A03/2A07

• based on mos 6502

• 2a03 vs mos 6502

  • • bcd mode
  • • timer
  • • dma
  • • sound system

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PART 2

• cpu
• MEMORY
• graphics
• sound
• controllers

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MEMORY

• two memory chips
  • program+data
  • graphics data
• no built-in rom
• eprom on cartridge

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MEMORY

• 2KB RAM
• 256B OAM
  • sprites
• 28B RAM pal.

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PART 3

• cpu
• memory
• GRAPHICS
• sound
• controllers

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GRAPHICS

• generated by PPU
• 256 X 240 pixels
• RP2C02/RP2C07
• a bit complicated
  • multiple tables

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GRAPHICS

• 256B sprite RAM
• 2KB backgr. RAM
• ROM on cartridge
• 64 color system palette

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GRAPHICS

• design strategy
• as few CPU cycles
• as possible

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BACKGROUND #1

• 256 X 240 pixels
  • not bitmap
  • tiles 8 X 8
  • groups 4 X 4
  • 4 palettes
  • 4 colors each
    • 3 unique/1 shared

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BACKGROUND #2

• PATTERN TABLE
  • in ROM
  • tiles 8 X 8
  • 2 bpp

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BACKGROUND #2B

• PATTERN TABLE size 16 bytes per tile
  • 256 tiles = 4096 bytes

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BACKGROUND #3

• ATTRIBUTE TABLE
  • 64 (60) bytes
  • upper 2 bits
  • for 4 X 4 tiles -> 32 X 32 pixels

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BACKGROUND #3B

• why?
  • tiles 2bpp -> palette #
  • attrib. 2bpp -> color from palette –

BACKGROUND #4

• NAME TABLE
  • in RAM
  • grid 32 X 30
  • offsets
  • 960 bytes
• can be manipulated quickly

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BACKGROUND #5

• PPU rendering:
  • read tile # from NAME TABLE
  • read palette # from ATTRIB.T.
  • read pixel colors from PATTERN TABLE

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BACKGROUND #5B

• without CPU intervention

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SPRITES #1

• PATTERN TABLE
  • in ROM
  • tiles 8 X 8
  • 2 bpp
• SPRITE RAM
  • 256 bytes

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SPRITES #3

• SPRITE RAM
• 64 sprites
• 4 bytes/sprite
  • tile #
  • x-position
  • y-position
  • attributes

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SPRITES #4

• attribues
  • palette 4-7
  • priority
  • horizontal flip
  • vertical flip

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TOTAL COLORS

• background
• sprites
• sum

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TOTAL COLORS

• background
  • main bg.color
  • 4 palettes
  • each 3 colors
  • 13 in overall

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TOTAL COLORS

• sprites
  • 4 palettes
  • each 3 colors
  • 12 in overall

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TOTAL COLORS

• summary
  • 25 colors on screen w/o any tricks

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PART 4

• cpu
• memory
• graphics
• SOUND
• controllers

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SOUND

• generated by cpu
• 2A03/2A07

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2A03 SOUND SYSTEM

• 5 channels
• 2 square waves
• 1 triangle wave
• 1 noise generator

• 1 d/a converter

• 22 control regs

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2A03 SQUARE WAVES

• 54.6 hz-12,4 khz
• 4 bit amplitude
• variable duty
• 1:8
• 1:4
• 1:2
• 3:4

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2A03 TRIANGLE WAVE

• 27.3 hz - 55.9 khz
• 4 bit amplitude
• automatic control

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2A03 NOISE GENERATOR

• 15 bit lfsr
• 29.3 hz - 447 khz
• two modes
• long
• 32767 bit cycle
• short

• 93 bit cycle

2A03 D/A CONVERTER

• dmc
  • delta modulation
• 7 bit
• 4.2 khz - 33.5 khz
• semi automatic dma
• non-linear d/a

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PART 5

• cpu
• memory
• graphics
• sound
• CONTROLLERS

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CONTROLLERS

• two controllers
• d-pad
• four buttons
  • A
  • B
  • START
  • SELECT

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CONTROLLERS

• theoretically
  • 8 pins
  • similar to atari, c64, …
• actually
  • serial io
  • latch
  • shift register

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CONTROLLERS

• latch values
• read from shift register
  • 8X lda
• LDA + AND + BEQ

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EXAMPLES

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THANK YOU