matt:~ %more snestech.txt
Memory Map
~~~~~~~~~~
Bank Address
~~~~ ~~~~~~~
00- 0000-1fff Lo RAM (same as at $7e0000-$7e1fff)
7d 2100-2142(?) Videochip Registers
4300-437f DMA Registers
8000-ffff ROM:This contains 32k block of game ROM.
So, the games are divided to 32k chunks
which locate always at address $8000-$ffff,
but in different banks. This means that the first
32k of game is at $008000-$00ffff and next 32k
is at $018000-$01ffff etc.
7e 0000-1fff Lo RAM (same as always at $0000-$1fff) \
2000-ffff RAM \ I'm not sure about } 128k RAM
7f 0000-ffff RAM / this RAM /
7f-ff all Not used???
$ffec($fffc) contains reset vector and $ffea($fffa) is NMI vector. The NMI is
actually vertical blank interrupt.
$ffc0 Cartridge Title
$ffd6 Rom/Ram Info On Cart
$ffd7 Rom Size
$ffd8 Ram Size
$ffd9 Maker ID Code
$ffdb Version Number
$ffdc Checksum Complement
$ffde Checksum
....
$ffec Reset Vector
etc..
REMEMBER with magicom files the offset is $7e00 less than above.
Video Chip
~~~~~~~~~~
size loc.
~~~~ ~~~~
B 2100 Screen fade x000bbbb x=screen on/off b=brightness(0-f)
B 2101 Sprite Sizes aaaxxxxx aaa= 2 sizes used xxxxx = address
W 2102 Address of OAM - Sprites to the rest of us.
2B 2104 Data for OAM
B 2105 Screen Mode abcd0xyz abcd = toggles 8/16 tile size xyz=Mode
B 2106 Screen Mozaik xxxxbbbb x=pixel size b=planes to expand
B 2107 Plane 0 location in vram xxxxxxab x=address ab=32/64 width xy
B 2108 Plane 1 location in vram xxxxxxab as above
B 2109 Plane 2 location in vram xxxxxxab as above
B 210a Plane 3 location in vram xxxxxxab as above
B 210b Tile VRAM address aaaabbbb a=Playfield 1 b=Playfield 0
B 210c Tile VRAM address ccccdddd c=Playfield 3 d=Playfield 2
2B 210d Plane 0 scroll x 8+3 bits (0-7ff) put first 8 bits and then
2B 210e Plane 0 scroll y 8+3 bits (0-7ff) 3 highest bits
2B 210f Plane 1 scroll x as above
2B 2110 Plane 1 scroll y as above
2B 2111 Plane 2 scroll x as above
2B 2112 Plane 2 scroll y as above
2B 2113 Plane 3 scroll x as above
2B 2114 Plane 3 scroll y as above
B 2115 Video port control
W 2116 Video port address (lo-hi)
W 2118 Video port data (lo-hi) (address is incremented by 2)
B 211a Mode 7 Info - Bit 0+1 H/V Flip 6+7 - landscape repeat type
B 211b Cosine rotate angle / X Expansion
B 211c Sine rotate angle / X Expansion
B 211d - Sine rotate angle / Y expansion
B 211e cosine rotate angle / Y expansion
2B 211f 13 bit address - centre of rotate x
2B 2120 13 bit address - centre of rotate y
B 2121 Palette color nr
B 2122 Palette color data
B 212C Playfield/Sprite Enable vwyzabcd a-d = playfield no..
vwyz = sprite enables
B 2133 Screen mode 0000ab0c a=Interlace Y b=Overscan c=Interlace X??
2140-2143 Audio Registers
I/O
~~~
B 4200 Bit 4+5 H+V Counter Enable
B 4201 8 Bit parallel data (expansion bus under famicom)
W B 420b Start dma (enable bits) bits: 76543210 = dma nr (8 DMA's)
B 420d Memory Select - bit 0 is fast/normal rom flip..
B 4211 Bit 7 IRQ enable flag
R B 4212 Pad ready to be read
R W 4218 Pad 0 data 76543210 = A-B-Select-Start-U-D-L-R
4219 76543210 = X-Y-Top Left-Top Right-0000
R W 421a Pad 1 data as above
R W 421c Pad 2 data as above
R W 421e Pad 3 data as above
DMA registers ($4300-$437f)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
B 43X0 DMA control reg??(not sure!)
B 43X1 DMA destination (Access only to some of the video chip
registers ($2100-$21ff)
$18=video port $22=color palette
W 43X2 Source address lo-hi 16 lowest bits
B 43X4 Source Bank addr. 8 highest bits
W 43X5 Transfer size lo-hi
X=dma number (0-7) DMA #0= 4300-4305
DMA #1= 4310-4315 ...
DMA #7= 4370-4375
Symbols: size: B=byte long 2B=put 2 bytes W=word long
R=read only W=write only
Screen Mode Defintions
~~~~~~~~~~~~~~~~~~~~~~~
Mode No/Playfields Max. Col/tile Palettes Colors
0 4 4 8 32
1 3 16/16/4 8 128
2 2 16 8 128
3 2 256 1 256
4 2 256 1 256
5 2 16 8 128
6 1 16 8 128 - interlace mode
7 1 256 1 256 - MODE 7!!!!
Sprites (or OAM's as Nintendo deem them)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
These use a lookup table that contains the info on position size etc.. the table
format is as follows :-
Address Contents
0 Sprite 0 X location
1 Sprite 0 Y location
2+3 Lo/Hi := Bit 15/14 V/H Flip
Bit 12+13 Playfield priority
Bit 9-11 Palette Number
Bit 0-8 Character NUmber
4 Sprite 1 X location
.....
all the way down to 128 sprites..
then a block follows that uses 2 bit for each sprite ie byte 0 of this block con
tains info
for sprites 0,1,2 and 3 - therefore 128/4 = 32 bytes!!!
lo bit of these 2 is the MSB of X position
hi bit of these 2 is the size toggle - set in 2101 the 2 sizes - 000 in 2101 =
8x8 or 16x16
001 =
8x8 or 32x32
so the four bytes/sprites + the block are put in the OAM table by consecutive wr
ites to the
OAM data register - set OAM address to 0 and then zap your table into OAM_Data .
..
REMEMBER - if you dont set the block after the OAM as well - you will probs get
nowt happenin!!
- so have a default 'blank' table that u dump down at the start..
Magicom registers
~~~~~~~~~~~~~~~~~
Disk Registers:- R W
$C000 Input Register
$C002 Digital Output Register
$C004 Main Status Reg.
$C005 Data Register Data Register
$C007 Digital Input Reg. Disk Control Register
$C008 Parallel Data Parallel Data
$C009 Parallel Status
Memory Controller:-
$E000 - $e00d ish
Screen Details
~~~~~~~~~~~~~~
Famicom Tile format is simple. Each Tile is 4 planes and 8x8 bits.
32 bytes are used per Tile .
PLANES 1 & 2 PLANES 3 & 4
byte0 byte1 byte 16 byte 17
byte2 byte3 byte 18 byte 19
byte4 byte5 byte 20 byte 21
..... .......
byte14 byte15 byte 30 byte 31
Screen Map
~~~~~~~~~~
Famicom can use only Tiles $0-$3ff, max 1024 chars.
16 bits: YX?c ccNN NNNN NNNN
fedc ba98 7654 3210
Y = mirror y X = mirror x
ccc = palette nr (8 palettes) NN.. = character number
Screen Resolution is normally 32x32 chars but only the first 30 y blocks are
visible (until scrolled) - 64 bytes / line
Screen VRAM Location
~~~~~~~~~~~~~~~~~~~~
Screen Width 32x32 offset for x,y 0,0 = 0
Screen Width 64x32 offset for x,y 0,0 = 0
32,0 = $400
Screen Width 32x64 offset for x,y 0,0 = 0
0,32 = $400
Screen Width 64x64 offset for x,y 0,0 = 0
32,0 = $400
0,32 = $800
32,32 = $c00
As can be seen if a wider mode is selected the extra height/width follow
after the main screen in memory.
The Nintendo Super Famicom is capable of displaying 256 colours from a
palette of 32,768. These 256 colours are split into 8 palettes of 32 colours
each.
To change the colours the following needs to be done:
Loading the palette control register ($2121) with the colour number you wish
to change (0-255, 0=background).
Then load the colour into the palette data register first the low 8 bits,
followed by the high 7 bits (this gives you the maximum 32768 colours
possible $0000-$7fff).
Colour data is made up of 3 components (Red,Green,Blue) each of 5 bits (The
Amiga uses exactly the same system, but only using 4 bits per component).
Saying that, Nintendo being the stupid japanese idiots they are decided that
R,G,B wasn't alphabetically correct and so opted to store the bits as B,G,R.
00000 00000 00000
\ / \ / \ /
\ / \ / \ /
B G R
Examples:
~~~~~~~~~
11111 00000 00000 = $7C00 (Bright Blue)
00000 11111 00000 = $03E0 (Bright Green)
00000 00000 11111 = $001F (Bright Red)
00000 00000 00000 = $0000 (Black)
11111 11111 11111 = $7FFF (White)
Easy, isn't it?? (But remember to load the lowest 8 bits first, then the top
7 bits).
matt:~ %