Zandra ULTRACHIP

Virtual machine based on CHIP-8, with the following improvements:

• Legacy stuff removed (ETI-660 compatibility, reserved memory for interpreter, and SYS instruction)
• 16-bit memory addressing, with 64KiB program/data space
• 64x64 display using a 16 color 16-bit RGB color palette.
• Improved sound system (maybe?)

Display

The display is a 16 color 64x64 display using a 16-bit RGB color palette, organized like so:

+-----------------+
|(0,0)      (64,0)|
|                 |
|                 |
|                 |
|                 |
|                 |
|(0,64)    (64,64)|
+-----------------+

Memory map

+-----------------+ 0xFFFF (65535) End of RAM
|                 |
|                 |
|                 |
|                 |
|                 |
| 0x000 to 0xFFFF |
|    ULTRACHIP    |
| Program / Data  |
|     Space       |
|                 |
|                 |
|                 |
+-----------------+ 0x000 (0) Start of RAM

Registers

• V0-VF: General purpose
• PC: Program counter
• SP: Stack pointer
• C: Carry flag
• TODO Timer and Sound registers

Instruction set

• 00E0: CLS: clear screen
• 00EE: RET: return from subroutine
• 1nnn: JP addr: PC=nnn
• 2nnn: CALL addr: SP++; S[SP]=PC; PC=nnn
• 3xkk: SE Vx, byte: Skip next instruction if Vx=kk
• 4xkk: SNE Vx, byte: Skip next instruction if Vx!=kk
• 5xy0: SE Vx, Vy: Skip next instruction if Vx=Vy
• 6xkk: LD Vx, byte: Vx=kk
• 7xkk: ADD Vx, byte: Vx=Vx+kk
• 8xy0: LD Vx, Vy: Vx=Vy
• 8xy1: OR Vx, Vy: Vx=Vx OR Vy
• 8xy2: AND Vx, Vy: Vx=Vx AND Vy
• 8xy3: XOR Vx, Vy: Vx=Vx XOR Vy
• 8xy4: ADD Vx, Vy: Vx=Vx + Vy; If (Vx > 255) C=1, else 0. Store lower 8 bits
• 8xy5: SUB Vx, Vy: Vx=Vx - Vy; If (Vx > Vy) VF=1, else 0
• TODO finish

Sound

TODO

Sprites

TODO