Wait cycle

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A wait cycle is a 68k bus cycle with no effects, the purpose of it is to allow the use of slow memories by "waiting" for them.

The NeoGeo provides wait state generation for 3 memory zones:

  • 000000~0FFFFF: P ROM - Configurable, 0 or 1 cycle
  • 200000~2FFFFF: P ROM - Configurable, 0, 1 or more cycles
  • 800000~BFFFFF: Memory card - Fixed, 2 cycles

Configuration is done by setting levels of the following cartridge pins:

  • ROMWAIT for 1 cycle in 000000~0FFFFF
  • PWAIT0 for 1 cycle in 200000~2FFFFF ?
  • PWAIT1 to enable PDTACK as a DTACK for 200000~2FFFFF ?