Day 5 release for Open Source Week!
Fully featured 8 bit game console with the following features:
- Custom Assembler
- Custom ISA (Similar to 6502 assembly)
- Custom 8 bit CPU
- Custom Audio drivers with 4 8 bit audio channels
- Future games incoming!
Display size of 256x256 (1:1 aspect ratio) Maximum color pallete of 8 colors at any time. Display is rendered at 60 FPS with a double buffer (Screen only needs to be drawn at 30 fps)
64 indivisual frequencies 21-85 (A0-C#6 on the MIDI scale) 4 channels of Audio Channel 0: Sine Channel 1: Square Channel 2: Triangle Channel 3: Noise
Helios comes with an assembler for it's own custom ISA. The assembly time is extremely fast (under 10ms) due to it's simplicity over modeern x86 assembly machines.
Helios currently supports the following Addressing modes:
| Type of Addressing Mode | Supported? |
|---|---|
| Immediate | Yes! |
| Zero-page | Yes! |
| Absolute | Yes! |
| Relative | No |
| Indirect | No |
Helios also now supports writing labels in assembly and jumping between labels.
Read some example ROMs in the roms directory
Helios comes with a 6502 inspired instruction set architecture. Here is a long list of all instructions currently implemented.
| Instruction | OPCODE |
|---|---|
| LDA_IMM | 0xA9 |
| LDA_ZP | 0xA5 |
| LDA_ZPX | 0xB5 |
| LDA_ABS | 0xAD |
| LDX_IMM | 0xA2 |
| LDY_IMM | 0xA0 |
| STA_ZP | 0x85 |
| STA_ZPX | 0x95 |
| STA_ABS | 0x8D |
| STX_ZP | 0x86 |
| STY_ZP | 0x84 |
| TAX | 0xAA |
| TAY | 0xA8 |
| TXA | 0x8A |
| TYA | 0x98 |
| ADC_IMM | 0x69 |
| SBC_IMM | 0xE9 |
| AND_IMM | 0x29 |
| ORA_IMM | 0x09 |
| EOR_IMM | 0x49 |
| INC_ZP | 0xE6 |
| DEC_ZP | 0xC6 |
| INX | 0xE8 |
| INY | 0xC8 |
| DEX | 0xCA |
| DEY | 0x88 |
| CMP_IMM | 0xC9 |
| CPX_ZP | 0xE0 |
| CPY_ZP | 0xC0 |
| JMP_ABS | 0x4C |
| JSR_ABS | 0x20 |
| RTS | 0x60 |
| BEQ | 0xF0 |
| BNE | 0xD0 |
| BCS | 0xB0 |
| BCC | 0x90 |
| BMI | 0x30 |
| BPL | 0x10 |
| NOP | 0xEA |
| BRK | 0x00 |
| HLT | 0xFF |
| DBG | 0xDE |
| SND | 0x42 |
Note: Some of these instructions are custom like DBG and SND.
DBG (Debug) is an instruction which accepts an absolute memory address and will print the value at that memory address into stdout to be debugged. This instruction does not have any other address modes
SND (Sound) is an instruction which accepts an immediete value to be added into the audio buffer. The 8 bit value should follow the correct audio bit convention shown Here This instruction does not have any other address modes
Helios was released as the day 5 submission to Open Source Week. I could not be any more greatful to those who decisde to submit bug fixes or new features in pull requests. Please, by all means, contribute your code to this repository to improve the project!
Some things I did not have the time to implement but i plan to implement in the future are:
- Keyboard input
- Game library
- Save states
- More custom utility instructions in the ISA
- Tools for converting MP3 audio into tracked audio
- Performance improvements
THANK YOU FOR ALL YOUR SUPPORT!