System Information:
Main CPU is a Motorola 68000 at 10 Mhz with 64K RAM ( + video RAM )
Sound CPU is a Zilog Z80 (at 4 Mhz ?)
Sounds chip are Yamaha 2151 (FM) and 3012 (DAC)
Memory Map:
$00000000 Main 68000 code + misc. data
$0001FFFF
$00400000 Scroll video RAM
$0040FFFF
$00410000 Fixed video RAM (text page) + video registers
$00410FFF
$00440000 Sprites control registers
$004403FF
$00840000 Color memory (2048 palette registers)
$00840FFF
$00C40000 I/O Registers
$FFFE0007 Used to control the Z80 program (for sound)
$FFFFC000 Main RAM
$FFFFFFFF
Scroll Video Ram:
The scroll video RAM can contain up to 16384 tiles (256 lines of 64
characters). There are 2 bytes for each tile, this is the format:
AAAAAAAA BBBBBBBB B7->B0 Tiles number in the bank (256)
+76543210+76543210+ A3->A0 Bank selector (16)
+--------+--------+ A4 Bank page selection (32 banks/page, 256 chars/bank)
A5 Priority flag
A7->A6 *function not found yet*
Colors: the color base register number is BANK * 4.
Bank selection: If bit A4=0 the bank selected is the value of A3 to A0,
if A4 is set to 1 the bank number is:
(value of A3 to A0) * 16 * (value of byte $FFFFF095)
Fixed Video RAM
The fixed video RAM can contain up to 2048 tiles (but only 26 lines of 42
characters are used). There are 2 bytes for each tile, this is the format:
AAAAAAAA BBBBBBBB B7->B0 Tiles number in the bank (256)
+76543210+76543210+ A0 Bank selector (0 or 1 only)
+--------+--------+ A7->A1 Color selector
Color Video Ram:
The color video RAM can contain up to 2048 color registers. The 1024 first
registers are used for text and scroll video display and the last 1024 are
used for sprites. There are 2 bytes for each register, this is the format:
Palette:
GBGRBBBB GGGGRRRR R4->R0 Red value (0-15)
+54443210+32103210+ G0->G5 Green value (0-31)
+--------+--------+ B4->B0 Blue Value (0-15)
Main Ram:
This memory contains, RAM, registers and SRAM.
Some special bytes:
F018: if bit5 is set 1, the screen is not updated
F01C: Timer ?
F01E: Sprites inactive if set to 0xFF
FF00-FFFF : SRAM in Altered Beast and normal RAM in Shinobi.
Video Registers:
$410E98 Horizontal foreground scroll register (Word)
$410E9A Horizontal background scroll register (Word)
$410E90 Vertical background scroll register (Byte)
$410E92 Vertical foreground scroll register (Byte)
$418000 Refresh enable
$20 Enable refresh
$01 Clear screen
$418028 Video page selection register for background (Word)
$418038 Video page selection register for foreground (Word)
$440000 The sprites registers. There are 16 control bytes for each
$4403FF sprite (64 sprites maximum).
0 bottom-- top----- (screen coordinates)
1 ???????X XXXXXXXX (screen coordinate)
2 ???????F FWWWWWWW (flipx, flipy, logical width)
3 TTTTTTTT TTTTTTTT (pen data)
4 ????BBBB PPCCCCCC (attributes: bank, priority, color)
5 ??????ZZ ZZZZZZZZ zoomx
6 ??????ZZ ZZZZZZZZ zoomy (defaults to zoomx)
7 ? "sprite offset"
$00 : last sprite line on the screen
$01 : first sprites line on the screen (sprites height = [00]-[01])
$02 : high value of the sprite X position
$03 : low value of the sprite X position (X = [02] * 256 + [03])
$04 : horizontal sprite flipping flag (flip if value = 01)
$05 : sprite width (real width = [05] * 2) (!! signed byte)
if the bit7 is set to 1, the sprite is flipped vertically
$06 : high value of sprite rom position
$07 : low value of sprite rom position
$08 : sprite bank selector
bit7-bit4 are always at 1 if the sprite is active
bit3-bit0 is the sprite bank number (0-F)
$09 : sprites priority and base color register selector
bit7-bit6: 10 - foreground sprite
01 - background sprite
11 - sprite over everything
bit5-bit0: base color registers (is 1024 + 16 * value)
$0A : zoom function \
$0B : zoom function - unknown format (never used in Shinobi)
$0C to $0F are not used in current emulated games
The sprite location in bank is ([06] * 256 + [07] + [05]) * 2
I/O Registers:
$C41003 1st Player Control
Bit 0 - Magic Bit 4 - Down
Bit 1 - Attack Bit 5 - Up
Bit 2 - Jump Bit 6 - Right
Bit 3 - Unused Bit 7 - Left
$C41007 2nd Player Control same as 1P
$C41001 General Controls
Bit 0 - Coin 1 Bit 4 - 1P Start
Bit 1 - Coin 2 Bit 5 - 2P Start
Bit 2 - Test Bit 6 - Unused
Bit 3 - Service Bit 7 - Unused
$C42001 Dip Switch settings #1 - Game configuration
$C42003 Dip Switch settings #2 - Coin configuration
Graphics Formats:
The sprites: there are 4 bits / pixels (16 colors), colors 0 and 15 are
used for transparency. There are 2 pixels coded in each byte, the first
pixel coded in bit7 to 4 and the second in bit3 to 0.
The tiles: the size is 8x8 pixels and there are 3 bits / pixels
(8 colors), color 0 is used for transparency.
Sega System 16 Video Hardware:
Each scrolling layer (foreground, background) is an arrangement
of 4 pages selected from 16 available pages, laid out as follows:
Page0 Page1
Page2 Page3
Each page is an arrangement of 8x8 tiles, 64 tiles wide, and
32 tiles high.
