CHIP-8 virtual machine emulator - Load chip8 ROMs in the prime

[Mark Power]

I've put together a Chip-8 App using file handling from the Gallery (PNG Viewer) App and an alternative emulator I put together. I've included Pong, Space Invaders and Tetris ROMs as samples. You can find more at http://chip8.com/?page=109.

This is only the first version so some tuning is needed.

To copy additional Chip8 ROMs to your calculator, open the HP Connectivity Kit and load Chip8 ROMS into the "Files" Folder inside Chip8 App.
Then, open the Chip8 App from Connectivity Kit and Press Save Button.

*Press [VIEW] to access the Menu.
*To Open a File, select Open and then select the file.
*To Delete a File, select Delete and then select the file, or just select Delete ALL.

Keyboard mapping (calculator to Chip8)
789/ 123C
456* 456D
123- 789E
0. + A0BF

Bugs:
*Screen size needs fixing, but when I turn BLIT scaling on in display_sprite the calculator hangs. See lines 375 onwards.
*Timing is wrong, just fast enough on the calculator to play, but way too fast on the emulator.

Thanks to:
*Andrés Vélez (mandresve) manuel.velez@uptc.edu.co for the App framework
*Vik2015 for chip8.c which is the basis of the emulator