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seta/st0016.cpp: Improve documentation comments based on PR#7786. [cam900]
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@ -260,7 +260,7 @@ u8 st0016_cpu_device::vregs_r(offs_t offset)
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/*
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/*
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$0, $1 = max scanline(including vblank)/timer? ($3e7)
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$0, $1 = max scanline(including vblank)/timer? ($3e7)
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$8-$40 = bg tilemaps (8 bytes each) :
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$8-$3F = bg tilemaps (8 bytes each) :
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0 - ? = usually 0/20/ba*
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0 - ? = usually 0/20/ba*
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1 - 0 = disabled , !zero = address of tilemap in spriteram /$1000 (for example: 3 -> tilemap at $3000 )
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1 - 0 = disabled , !zero = address of tilemap in spriteram /$1000 (for example: 3 -> tilemap at $3000 )
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2 - ? = usually ff/1f/af*
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2 - ? = usually ff/1f/af*
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@ -270,7 +270,7 @@ u8 st0016_cpu_device::vregs_r(offs_t offset)
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6 - ? = 0
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6 - ? = 0
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7 - ? =$20/$10/$12*
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7 - ? =$20/$10/$12*
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$40-$60 = scroll registers , X.w, Y.w
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$40-$5F = scroll registers , X.w, Y.w
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*/
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*/
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switch (offset)
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switch (offset)
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@ -299,27 +299,44 @@ void st0016_cpu_device::vregs_w(offs_t offset, u8 data)
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I/O ports:
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I/O ports:
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$74 x--- ---- global flip screen
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$60 \
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-xx- ---- individual flip screen x/y
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$61 - H sync start?
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i.e. Mayjinsen sets 0x80, other ST0016 games 0x60.
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$62 \
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TODO: Might also be paired with $70 & $75 (setted up by Mayjinsen).
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$63 - H visible start?
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$64 \
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$65 - H visible end >> 1?
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$66 \
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$67 - H total
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$68 \
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$69 - V sync start?
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$6a \
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$6b - V visible start?
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$6c \
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$6d - V visible end?
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$6e \
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$6f - V total
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$a0 \
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$74 x--- ---- global flip screen
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$a1 - source address >> 1
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-xx- ---- individual flip screen x/y
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$a2 /
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i.e. Mayjinsen sets 0x80, other ST0016 games 0x60.
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TODO: Might also be paired with $70 & $75 (setted up by Mayjinsen).
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$a3 \
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$a0 \
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$a4 - destination address >> 1 (inside character ram)
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$a1 - source address >> 1
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$a5 /
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$a2 /
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$a6 \
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$a3 \
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&a7 - (length inbytes - 1 ) >> 1
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$a4 - destination address >> 1 (inside character ram)
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$a5 /
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$a8 - 76543210
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$a6 \
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??faaaaa
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&a7 - (length inbytes - 1 ) >> 1
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a - most sign. bits of length
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$a8 - 76543210
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f - DMA start latch
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??faaaaa
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a - most sign. bits of length
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f - DMA start latch
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*/
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*/
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