GitHub - piot/enias: 8 bit fantasy console (original) (raw)
Enias
8-bit Fantasy Console!
Compile
Make sure that you have the sdl2 libraries installed.
cd src
./compile.sh
./enias examples/hackman/hackman.prg
Memory Layout
All addresses are "indirect". The 16-bit value stored is used as the actual address.
| Memory Address | Size | Name | Description |
|---|---|---|---|
| Cpu | |||
| 0000−0000-0000−00FF | $0100 | ZP | Zero page (registers / scratch area) |
| 0100−0100-0100−01FF | $0100 | Stack | |
| Program | |||
| 0200−0200-0200−AFFF | $AE00 | Program area | |
| Graphics | |||
| B000−B000-B000−CFFF | $2000 | tiles | 256 tiles (8x8) each pixel is 4-bit. (8 rows with 32 tiles) sprites and nametable. |
| D000−D000-D000−EFFF | $2000 | extended tiles | 256 tiles (8x8) each pixel is 4-bit. Can only be used for sprites. |
| F000−F000-F000−F3FF | 0400∣nametable(default)∣0400 | nametable (default) | 0400∣nametable(default)∣F000 = upper-left, F100=upper−right,F100 = upper-right, F100=upper−right,F200 = bottom-left, $F300 = bottom right. |
| F400−F400-F400−F4FF | $0100 | sprites (default) | |
| F500−F500-F500−F52F | $0030 | palette | 16 entries with R,G,B (three octets) |
| F530−F530-F530−F533 | 0004∣nametablescrolling∣0004 | nametable scrolling | 0004∣nametablescrolling∣F530 x-offset (0-255), F531(0/1),F531 (0/1), F531(0/1),F532 y-offset (0-255), $F533 (0/1) |
| Audio | |||
| F600−F600-F600−F8BF | $02C0 | 64 waves (x 11 octets) | |
| F900−F900-F900−F977 | $0078 | 24 instruments (x 5 octets) | |
| FA00−FA00-FA00−FAAF | $00B0 | 16 channels | |
| FAF0−FAF0-FAF0−FAF7 | $0008 | Effects | |
| Input | |||
| FB00∣FB00 | FB00∣0008 | Gamepad 4 x 2 octets | |
| FB08∣FB08 | FB08∣0001 | Keyboard input | |
| Reserved | |||
| FB09−FB09-FB09−FEFF | $0500 | Reserved | |
| Vectors | |||
| FFFC−FFFC-FFFC−FFFD | 0002∣Resetcalladdress.∣Defaultsto0002 | Reset call address. | Defaults to 0002∣Resetcalladdress.∣Defaultsto0200 |
| FFFE−FFFE-FFFE−FFFF | 0002∣Framecalladdress.∣Defaultsto0002 | Frame call address. | Defaults to 0002∣Framecalladdress.∣Defaultsto0200 |
Tiles
Each tile is 8x8 pixels, with four bits for each pixel. The pixel value is an actual index lookup into the palette. 0 (zero) is always considered to be transparent.
Sprites
Usually starts at $FD00
| Octet Offset | Name | bits | Description |
|---|---|---|---|
| 0 | x | xxxxxxxx | from left to right |
| 1 | y | yyyyyyyy | top to bottom |
| 2 | tile | tttttttt | tile index (each row is 32 tiles) |
| 3 | status | vhp0000t | v: vertical flip, h: horizontal flip, p: priority (0 = behind background tiles) t: add 256 to tile index |
Palette
16 palette entries. Each entry is:
| Octet Offset | Name |
|---|---|
| 0 | red |
| 1 | green |
| 2 | blue |
Name-table
The index for each tile to be displayed from top-left corner (32x28), 896 octets.
| Octet Offset | Size | Name | Description |
|---|---|---|---|
| 0000∣0000 | 0000∣0100 | "top-left". 32x28 index to tiles. (last $80 tiles not used). | |
| 0100∣0100 | 0100∣0100 | "top-right". 32x28 index to tiles. (last $80 tiles not used). | |
| 0200∣0200 | 0200∣0100 | "bottom-left". 32x28 index to tiles. (last $80 tiles not used). | |
| 0300∣0300 | 0300∣0100 | "bottom-right". 32x28 index to tiles. (last $80 tiles not used). |
Input
Four gamepads, each has the following
| Octet Offset | Name | bits | Description |
|---|---|---|---|
| 0 | normal | abstudlr | 80A,80 A, 80A,40 B, 20Select,20 Select, 20Select,10 Start, 08Up,08 Up, 08Up,04 Down, 02Left,02 Left, 02Left,01 Right |
| 1 | extended | xylr0000 | 80X,80 X, 80X,40 Y, 20Lefttrigger,20 Left trigger, 20Lefttrigger,10 Right trigger |
Keyboard input
| Address | Name | Description |
|---|---|---|
| $FB08 | key | Latest pressed key (ASCII) or 0 (zero) if no key pressed |
Sound Chip
Voice / Channel
16 voices. Each voice has the following info:
| Octet Offset | Name | bits | Description |
|---|---|---|---|
| 0 | instrument | 000iiiii | index into instruments. (0-23) |
| 1 | note | kkkkkkkk | 0: key off |
| 2 | velocity | vvvvvvvv | |
| 3 | pan | vvvvvvvv | 0: all left, 255: all right |
| 4 | pitch | ffffffff | signed diff for key |
| 5 | volume | vvvvvvvv | |
| 6 | fx1-gain | ffffffff | fx1 = feed to reverb |
| 7 | fx2-gain | ffffffff | fx2 = feed to delay |
| 8 | low-pass | ffffffff | |
| 9 | high-pass | ffffffff | |
| A | q-filter | ffffffff |
Instrument (Sound definition)
24 Instruments.
| Octet Offset | Name | bits | Description |
|---|---|---|---|
| 0 | wave-index | wwwwwwww | 0-64. index into waves |
| 1 | attack | aaaaaaaa | time before maximum volume |
| 2 | decay | dddddddd | time before it reaches sustain volume |
| 3 | sustain | ssssssss | (optional?) volume level for the sustain part. |
| 4 | release | rrrrrrrr | (optional?) time before sound reaches zero volume. |
Wave
64 Waves.
| Octet Offset | Name | bits | Description |
|---|---|---|---|
| 0 | sample-pointer (low) | wwwwwwww | |
| 1 | sample-pointer (high) | wwwwwwww | |
| 2 | sample-length (low) | wwwwwwww | |
| 3 | sample-length (high) | wwwwwwww | |
| 4 | loop | wll00000 | w: (0=8-bit samples, 1:16-bit samples). loop-mode (0: no loop, 1: forward, 2: ping-pong) |
| 5 | loop start (low) | rrrrrrrr | loop start point |
| 6 | loop start (high) | rrrrrrrr | |
| 7 | loop length (low) | rrrrrrrr | loop length |
| 8 | loop length (high) | rrrrrrrr | |
| 9 | relative_note_number | rrrrrrrr | |
| A | volume | rrrrrrrr |
Effect settings
One global effect system
| Octet Offset | Name | bits | Description |
|---|---|---|---|
| 0 | reverb-mix | wwwwwwww | |
| 1 | delay-time | wwwwwwww | |
| 2 | delay-reflect | wwwwwwww | |
| 3 | delay-mix | wwwwwwww |
Samples
| Octet Offset | Name |
|---|---|
| 0 - x | 8/16-bit samples |