ONLY ORIGINAL CHIP-8 INSTRUCTIONS
| Opcode | Mnemonic | Description |
|---|---|---|
| 001N | EXIT N |
From Peter Miller's chip8run. Exit emulator with a return value of N. |
| 00E0 | CLS | Clears the display. Sets all pixels to off. |
| 00EE | RET | Return from subroutine. Set the PC to the address at the top of the stack and subtract 1 from the SP. |
| 00FA | COMPAT | Non-standard. Toggles changing of the I register by save (FX55) and restore (FX65) opcodes. |
| 0NNN | CALL NNN |
Call machine language subroutine at address NNN. |
| 1NNN | JMP NNN |
Set PC to NNN. |
| 2NNN | CALL NNN |
Call subroutine a NNN. Increment the SP and put the current PC value on the top of the stack. Then set the PC to NNN. Generally there is a limit of 16 successive calls. |
| 3XNN | SE VX, NN |
Skip the next instruction if register VX is equal to NN. |
| 4XNN | SNE VX, NN |
Skip the next instruction if register VX is not equal to NN. |
| 5XY0 | SE VX, VY |
Skip the next instruction if register VX equals VY. |
| 6XNN | LD VX, NN |
Load immediate value NN into register VX. |
| 7XNN | ADD VX, NN |
Add immediate value NN to register VX. Does not effect VF. |
| 8XY0 | LD VX, VY |
Copy the value in register VY into VX |
| 8XY1 | OR VX, VY |
Set VX equal to the bitwise or of the values in VX and VY. |
| 8XY2 | AND VX, VY |
Set VX equal to the bitwise and of the values in VX and VY. |
| 8XY3 | XOR VX, VY |
Set VX equal to the bitwise xor of the values in VX and VY. Note: This instruction was originally undocumented but functional due to how the 8XXX instructions were implemented on teh COSMAC VIP. |
| 8XY4 | ADD VX, VY |
Set VX equal to VX plus VY. In the case of an overflow VF is set to 1. Otherwise 0. |
| 8XY5 | SUB VX, VY |
Set VX equal to VX minus VY. In the case of an underflow VF is set 0. Otherwise 1. (VF = VX > VY) |
| 8XY6 | SHR VX, VY |
Set VX equal to VX bitshifted right 1. VF is set to the least significant bit of VX prior to the shift. Originally this opcode meant set VX equal to VY bitshifted right 1 but emulators and software seem to ignore VY now. Note: This instruction was originally undocumented but functional due to how the 8XXX instructions were implemented on teh COSMAC VIP. |
| 8XY7 | SUBN VX, VY |
Set VX equal to VY minus VX. VF is set to 1 if VY > VX. Otherwise 0. Note: This instruction was originally undocumented but functional due to how the 8XXX instructions were implemented on teh COSMAC VIP. |
| 8XYE | SHL VX, VY |
Set VX equal to VX bitshifted left 1. VF is set to the most significant bit of VX prior to the shift. Originally this opcode meant set VX equal to VY bitshifted left 1 but emulators and software seem to ignore VY now. Note: This instruction was originally undocumented but functional due to how the 8XXX instructions were implemented on teh COSMAC VIP. |
| 9XY0 | SNE VX, VY |
Skip the next instruction if VX does not equal VY. |
| ANNN | LD I, NNN |
Set I equal to NNN. |
| BNNN | JMP V0, NNN |
Set the PC to NNN plus the value in V0. |
| CXNN | RND VX, NN |
Set VX equal to a random number ranging from 0 to 255 which is logically anded with NN. |
| DXYN | DRW VX, VY, N |
Display N-byte sprite starting at memory location I at (VX, VY). Each set bit of xored with what's already drawn. VF is set to 1 if a collision occurs. 0 otherwise. |
| EX9E | SKP VX |
Skip the following instruction if the key represented by the value in VX is pressed. |
| EXA1 | SKNP VX |
Skip the following instruction if the key represented by the value in VX is not pressed. |
| FX07 | LD VX, DT |
Set VX equal to the delay timer. |
| FX0A | LD VX, KEY |
Wait for a key press and store the value of the key into VX. |
| FX15 | LD DT, VX |
Set the delay timer DT to VX. |
| FX18 | LD ST, VX |
Set the sound timer ST to VX. |
| FX1E | ADD I, VX |
Add VX to I. VF is set to 1 if I > 0x0FFF. Otherwise set to 0. |
| FX29 | LD I, FONT(VX) |
Set I to the address of the CHIP-8 8x5 font sprite representing the value in VX. |
| FX33 | BCD VX |
Convert that word to BCD and store the 3 digits at memory location I through I+2. I does not change. |
| FX55 | LD [I], VX |
Store registers V0 through VX in memory starting at location I. I does not change. |
| FX65 | LD VX, [I] |
Copy values from memory location I through I + X into registers V0 through VX. I does not change. |