www.espboy.com

Special thanks to:
- Igor (corax89) https://github.com/corax89
- DmitryL (Plague) https://github.com/PlagueRus
- John Earnest https://github.com/JohnEarnest/Octo 
and Alvaro Alea Fernandez https://github.com/alvaroalea for his Chip-8 emulator 

Implemented all known quirks to provide wide compatibility

Used information from https://github.com/JohnEarnest/Octo http://mattmik.com/chip8.html https://github.com/Chromatophore/HP48-Superchip

The games should be with extention ".ch8" as <gamename.ch8> To upload games to SPIFFS check: https://www.youtube.com/watch?v=25eLIdLKgHs

For correct compilation, use recommended Arduino IDE libs and settings

• SC – super chip game
• OJ – OCTO JAM game https://johnearnest.github.io/chip8Archive/
• ! – recommended to play
• HR – hires game

https://johnearnest.github.io/chip8Archive/

You is able to make <gamename.k> configuration files and upload them to the SPIFFS togather with games. It looks like simple txt file. Check below

The name of the configuration file should be the same as the game's name but with extention ".k" as <gamename.k>

4 2 8 6 5 11 4 6
13
0
1
67
30
60
200
Here could be description of the game about 300 symbols

Config file is simple txt with following parameters in every new line

• key mapping separated by spaces
• foreground color
• background color
• delay
• compatibility flags
• (depricated but still here to provide back comatibility) quantity of opcodes run before TFT updates
• timers frequency
• sound tone frequency
• .ch8 file description about 300 symbols

first line is the list of chi8 keys separated with spaces corresponding to ESPboy keys

ESPboy keys 0-LEFT, 1-UP, 2-DOWN, 3-RIGHT, 4-ACT, 5-ESC, 6-LFT side button, 7-RGT side button

Chip8 keys
1     2     3     C[12]
4     5     6     D[13]
7     8     9     E[14]
A[10] 0[0] B[11]  F[15]

no of color according to the list
0-BLACK 1-NAVY 2-DARKGREEN 3-DARKCYAN 4-MAROON 5-PURPLE 6-OLIVE 7-LIGHTGREY 8-DARKGREY 9-BLUE
10-GREEN 11-CYAN 12-RED 13-MAGENTA 14-YELLOW 15-WHITE 16-ORANGE 17-GREENYELLOW 18-PINK

no of color according to the same list

delay in microseconds before each instruction

are used to turn on/off few emulator quircks details https://github.com/Chromatophore/HP48-Superchip

8XY6/8XYE opcode Bit shifts a register by 1, VIP: shifts rY by one and places in rX, SCHIP: ignores rY field, shifts existing value in rX. bit1 = 1 <<= amd >>= takes vx, shifts, puts to vx, ignore vy bit1 = 0 <<= and >>= takes vy, shifts, puts to vx

FX55/FX65 opcode Saves/Loads registers up to X at I pointer - VIP: increases I by X, SCHIP: I remains static. bit2 = 1 load and store operations leave i unchaged bit2 = 0 I is set to I + X + 1 after operation

8XY4/8XY5/8XY7/ ??8XY6??and??8XYE?? bit3 = 1 arithmetic results write to vf after status flag bit3 = 0 vf write only status flag

DXYN bit4 = 1 wrapping sprites bit4 = 0 clip sprites at screen edges instead of wrapping

BNNN (aka jump0) Sets PC to address NNN + v0 - VIP: correctly jumps based on value in v0. SCHIP: also uses highest nibble of address to select register, instead of v0 (high nibble pulls double duty). Effectively, making it jumpN where target memory address is N##. Very awkward quirk. bit5 = 1 Jump to CurrentAddress+NN ;4 high bits of target address determines the offset register of jump0 instead of v0. bit5 = 0 Jump to address NNN+V0

DXYN check bit 8 bit6 = 1 drawsprite returns number of collised rows of the sprite + rows out of the screen lines of the sprite (check for bit8) bit6 = 0 drawsprite returns 1 if collision/s and 0 if no collision/s

(DEPRICATED) EMULATOR TFT DRAW bit7 = 1 draw to TFT just after changing pixel by drawsprite() not on timer bit7 = 0 redraw all TFT from display on timer

DXYN OUT OF SCREEN check bit 6 bit8 = 1 drawsprite does not add "number of out of the screen lines of the sprite" in returned value bit8 = 0 drawsprite add "number of out of the screen lines of the sprite" in returned value

0x1E ADI I = I + VX. SET reg I OVERFLOW BIT IN reg VF OR NOT bit9 = 1 set VF=1 in case of I ovelflow, overwise VF=0 bit9 = 0 VX stay unchanged after oveflowing reg I operation I = I + VX

for example for AstroDodge game should be set as (binary)01000011 = (decimal)67

DEPRICATED Quantity of opcodes runs till screen update. Works if you don't use TFT_DRAW bit7 of COMPATIBILITY FLAGS

Setting up the frequency of CHIP8 timers. Standart is 60Hz

the freq tone of sound

write 314 symbols of information you'll see before the game starts