address - data memo

kazzo 
<control pin status>
CPU PHI2 = H
CPU R/W  = H
PPU /RD  = H
PPU /WR  = H
<data bus status>
address|CPU         |PPU      |data
$0000- |empty       |memory   |hi-z
$2000- |empty       |empty(*2)|hi-z
$4000- |register(*1)|memory   |*1
$6000- |RAM         |empty(*2)|CPU RAM
$8000- |memory      |memory   |CPU memory
$a000- |memory      |empty(*2)|CPU memory
$c000- |memory      |memory   |CPU memory
$e000- |ROM         |empty(*2)|CPU ROM
  • empty is not mapped on cartridge
  • memory is RAM or ROM
  • *1 Some cartridges are assigned control register. eg. MMC5, namcot 163 variants and RP2C33.
  • *2 Some cartridges are assigned non-mirroring name table. It is known as 4-screen mirroring style.