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ff3:ff3us:doc:snes:register [2019/08/08 02:39] madsiur [Address Bus B Registers] |
ff3:ff3us:doc:snes:register [2019/08/08 02:57] madsiur [PPU1 Status and Version Number] |
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These values are latched by reading $2137 when bit 7 of $4201 is set, or by clearing-and-setting bit 7 of $4201 either by writing $4201 or by pin 6 of Controller Port 2 (the latch occurs on the 1->0 transition). Note that the value read is only 9 bits: bits 1-7 of the high byte are PPU2 Open Bus. Each register keeps seperate track of whether to return the low or high byte. The high/low selector is reset to ' | These values are latched by reading $2137 when bit 7 of $4201 is set, or by clearing-and-setting bit 7 of $4201 either by writing $4201 or by pin 6 of Controller Port 2 (the latch occurs on the 1->0 transition). Note that the value read is only 9 bits: bits 1-7 of the high byte are PPU2 Open Bus. Each register keeps seperate track of whether to return the low or high byte. The high/low selector is reset to ' | ||
+ | |||
+ | [[register# | ||
+ | |||
+ | ===== PPU1 Status and Version Number ===== | ||
+ | < | ||
+ | $213E r b++++ STAT77 - PPU1 Status and Version Number | ||
+ | trmuvvvv | ||
+ | t = OBJ Time overflow | ||
+ | r = OBJ Range overflow (0=Okay, 1=More than 32 OBJs per scanline) | ||
+ | m = Master/ | ||
+ | u = unused | ||
+ | vvvv = PPU1 5C77 Version Number (only version 1 exists) | ||
+ | </ | ||
+ | |||
+ | Bit t: If more than 34 sprite-tiles (e.g. a 16x16 sprite has 2 sprite-tiles) were encountered on a single line, this flag will be set. The flag is reset at the end of V-Blank but not during forced blank. | ||
+ | |||
+ | Bit r: If more than 32 sprites were encountered on a single line, this flag will be set. The flag is reset at the end of V-Blank but not during forced blank. | ||
+ | |||
+ | Note that the above two flags are set whether or not OBJ are actually enabled at the time (see $212C), at the following times: bit 6 when V=OBJ.YLOC/ | ||
[[register# | [[register# |