summaryrefslogtreecommitdiffstatshomepage
diff options
context:
space:
mode:
author arbee <rb6502@users.noreply.github.com>2024-05-19 12:01:34 -0400
committer arbee <rb6502@users.noreply.github.com>2024-05-19 12:01:34 -0400
commit340fbec1e4bbac40b63f76bb847af2c58f13d61f (patch)
tree365cfab846372c32b56bc8dd95d2ce102cb59975
parent698b634196ff8ea959c8c466e6afe5bf1a0922f4 (diff)
seta/st0016.cpp: Improve documentation comments based on PR#7786. [cam900]
-rw-r--r--src/mame/seta/st0016.cpp63
1 files changed, 40 insertions, 23 deletions
diff --git a/src/mame/seta/st0016.cpp b/src/mame/seta/st0016.cpp
index 425263fe8d1..dd3f1e61894 100644
--- a/src/mame/seta/st0016.cpp
+++ b/src/mame/seta/st0016.cpp
@@ -260,7 +260,7 @@ u8 st0016_cpu_device::vregs_r(offs_t offset)
/*
$0, $1 = max scanline(including vblank)/timer? ($3e7)
- $8-$40 = bg tilemaps (8 bytes each) :
+ $8-$3F = bg tilemaps (8 bytes each) :
0 - ? = usually 0/20/ba*
1 - 0 = disabled , !zero = address of tilemap in spriteram /$1000 (for example: 3 -> tilemap at $3000 )
2 - ? = usually ff/1f/af*
@@ -270,7 +270,7 @@ u8 st0016_cpu_device::vregs_r(offs_t offset)
6 - ? = 0
7 - ? =$20/$10/$12*
- $40-$60 = scroll registers , X.w, Y.w
+ $40-$5F = scroll registers , X.w, Y.w
*/
switch (offset)
@@ -299,27 +299,44 @@ void st0016_cpu_device::vregs_w(offs_t offset, u8 data)
I/O ports:
- $74 x--- ---- global flip screen
- -xx- ---- individual flip screen x/y
- i.e. Mayjinsen sets 0x80, other ST0016 games 0x60.
- TODO: Might also be paired with $70 & $75 (setted up by Mayjinsen).
-
- $a0 \
- $a1 - source address >> 1
- $a2 /
-
- $a3 \
- $a4 - destination address >> 1 (inside character ram)
- $a5 /
-
- $a6 \
- &a7 - (length inbytes - 1 ) >> 1
-
- $a8 - 76543210
- ??faaaaa
-
- a - most sign. bits of length
- f - DMA start latch
+ $60 \
+ $61 - H sync start?
+ $62 \
+ $63 - H visible start?
+ $64 \
+ $65 - H visible end >> 1?
+ $66 \
+ $67 - H total
+ $68 \
+ $69 - V sync start?
+ $6a \
+ $6b - V visible start?
+ $6c \
+ $6d - V visible end?
+ $6e \
+ $6f - V total
+
+ $74 x--- ---- global flip screen
+ -xx- ---- individual flip screen x/y
+ i.e. Mayjinsen sets 0x80, other ST0016 games 0x60.
+ TODO: Might also be paired with $70 & $75 (setted up by Mayjinsen).
+
+ $a0 \
+ $a1 - source address >> 1
+ $a2 /
+
+ $a3 \
+ $a4 - destination address >> 1 (inside character ram)
+ $a5 /
+
+ $a6 \
+ &a7 - (length inbytes - 1 ) >> 1
+
+ $a8 - 76543210
+ ??faaaaa
+
+ a - most sign. bits of length
+ f - DMA start latch
*/