System Information:
V33 (I86 based) CPU
YM2151 Sound chip (encrypted V33)
V33 Addresses:
$00000 $9ffff MRA_ROM
$A0000 $bffff MRA_BANK1
$C0000 $cffff Mirror of rom: Used by In The Hunt as protection
$D0000 $dffff Vram
$E0000 $effff System ram
$F0000 $f3fff Eeprom, Major Title 2 only
$F8000 $f87ff Sprite Ram
$F8800 $f8fff Palette Ram (xBBBBBGGGGGRRRRR)
$F9000 $f900f Sprite Control
$F9008 Clears Sprite Ram
$F9800 $f9801 Sprite Buffer
$FFFF0 $FFFFF MRA_ROM
Read Ports:
$00 Player 1 Input
$01 Player 2 Input
$02 Coins & VBL
$03 Dip 3
$04 Dip 2
$05 Dip 1
$06 Player 3
$07 Player 4
$08-$09 Status Port
Write Ports:
$00-$01 Sound Latch
$02-$03 Coin Counter
$20-$21 Bank Switch
$40-$43 Interrupt controller, only written to at bootup
$80-$87 Play Field 1 Control
$88-$8F Play Field 2 Control
$90-$97 Play Field 3 Control
$98-$9F Master Control
$C0-$C1 ?
Sound memory:
$00000-$1FFFF Rom
$FFFF0-$FFFFF Rom
Graphics:
3 scrolling playfields, 512 by 512.
Each playfield can enable rowscroll, change shape (to 1024 by 512),
be enabled/disabled and change position in VRAM.
Tiles can have several priority values:
0 = standard
1 = Top 8 pens appear over sprites (split tilemap)
2 = Whole tile appears over sprites
3 = ? Seems to be the whole tile is over sprites (as 2).
Sprites have 2 priority values:
0 = standard
1 = Sprite appears over all tiles, including high priority pf1
Raster interrupts can be triggered at any line of the screen redraw,
typically used in games like R-Type Leo to multiplex the top
playfield.
Master Control registers:
Word 0: Playfield 1 control
Bit 0x40: 1 = Rowscroll enable, 0 = disable
Bit 0x10: 0 = Playfield enable, 1 = disable
Bit 0x04: 0 = 512 x 512 playfield, 1 = 1024 x 512 playfield
Bits 0x03: Playfield location in VRAM (0, 0x4000, 0x8000, 0xc000)
Word 1: Playfield 2 control (as above)
Word 2: Playfield 3 control (as above)
Word 3: Raster IRQ position.
Byte 6 Byte 7
Raster Irq Position = (Position & $ff) + 128 | (Position & $ff00)
The raster IRQ position is offset by 128+8 from the first visible line,
suggesting there are 8 lines before the first visible one.
Gunforce waits on bit 1 (word) going high on bootup, just after
setting up interrupt controller.
Gunforce reads bit 2 (word) on every coin insert, doesn't seem to
do much though..
Ninja Batman polls this.
R-Type Leo reads it now & again..
m92_ram[$53]=1; /* FIXES RTYPE LEO! */
IRQs:
IRQ 0 VBL interrupt
IRQ 1 End of VBL interrupt??
IRQ 2 Raster interrupt
IRQ 3 Sprite buffer complete interrupt?
Tiles:
tile = Index + 1 << 8 | Index
color = [Index + 2] & $3f
[Index + 3] & 1 Highest priority;
[Index + 2] & $80 Medium priority
[Index + 3] & &6 Flip X and Y
Playfield 3 rowscroll data is $dfc00 - $dffff
Playfield 2 rowscroll data is $df800 - $dfbff
Playfield 1 rowscroll data is $df400 - $df7ff
It appears to be hardwired to those locations.
In addition, each playfield is staggered 2 pixels horizontally from the
previous one. This is most obvious in Hook & Blademaster.
Playfield Controls:
Scroll X Play Field Control[5] << 8) + Play Field Control[4]
Scroll Y Play Field Control[1] << 8) + Play Field Control[0]
Sprites:
y = (Spriteram[0] | Spriteram[1] << 8) & $1ff
x = (Spriteram[6] | Spriteram[7] << 8) & $1ff
sprite = Spriteram[2] | (Spriteram[3] << 8)
color = Spriteram[4] & $3f
Y Size = (Spriteram[1] >> 1) & $03 1, 2, 4 or 8
X Size = (Spriteram[1] >> 3) & $03 1, 2, 4 or 8
? Fixed X = Spriteram[5] & $01
? Fixed Y = Spriteram[5] & $02
I believe the spritechip interrupts the main CPU once sprite buffering is
complete, there isn't a whole lot of evidence for this but it's an idea.
Input:
Player 1 (Port 0)
$01 Right
$02 Left
$04 Down
$08 Up
$10 Unused
$20 Button 3
$40 Button 2
$80 Button 1
Extra Buttons
$01 Unused
$02 Button 4 (Player 1)
$04 Button 5 (Player 1)
$08 Button 6 (Player 1)
$10 Unused
$20 Button 4 (Player 2)
$40 Button 5 (Player 2)
$80 Button 6 (Player 2)
Graphics:
8 * 8 characters
65536 characters
4 bits per pixel
// The bitplanes are separated
Plane Offsets $180000 * 8 $100000 * 8 $80000 * 8 $000000 * 8
XOffsets 0 1 2 3 4 5 6 7
YOffsets 0 * 8 1 * 8 2 * 8 3 * 8 4 * 8 5 * 8 6 * 8 7 * 8
Every char takes 8 consecutive bytes
16 * 16 characters
32768 characters
4 bits per pixel
Plane Offsets $300000 * 8 $200000 * 8 $100000 * 8 $000000 * 8
XOffsets 0, 1, 2, 3, 4, 5, 6, 7,
16*8+0, 16*8+1, 16*8+2, 16*8+3, 16*8+4, 16*8+5, 16*8+6, 16*8+7
YOffsets 0*8, 1*8, 2*8, 3*8, 4*8, 5*8, 6*8, 7*8,
8*8, 9*8, 10*8, 11*8, 12*8, 13*8, 14*8, 15*8
Every character takes 32 consecutive bytes
16 * 16 characters
65536 characters
4 bits per pixel
Plane Offsets $600000 * 8 $400000 * 8 $200000 * 8 $000000 * 8
XOffsets 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7
YOffsets 0 * 16 1 * 16 2 * 16 3 * 16 4 * 16 5 * 16 6 * 16 7 * 16
8 * 16 9 * 16 10 * 16 11 * 16 12 * 16 13 * 16 14 * 16 15 * 16
Every character takes 32 consecutive bytes
