DECA board test core

Ported from Neptuno board test https://github.com/neptuno-fpga/board_test

Tested with PS2 & R2R VGA adapter (333) https://www.waveshare.com/vga-ps2-board.htm

Tested with 32 MB SDRAM board for MiSTer (extra slim) XS_2.2 (see connections)

Sound tested with Atlas (J2:1 left ye, J2:3 right gn)

PS2 mouse tested with Atlas board

Changelog:

• v0.1 VGA only. SDRAM working

Includes

• SDRAM test
• SD slot test
• Sigma delta sound test
• VGA / RGB PAL & NTSC test
• Keyboard & mouse tests
• Joystick 1 & 2 test (2 buttons for now)
• Addon SRAM test (1024x16)

Main changes to the core

• Pin definitions
• VGA 666 to 333

Screen