MSXgoauld_tn20k

MSX Goa'uld board with Tang Nano 20k

MSX2+ engine in Z80 socket. It turns one MSX into an MSX2+ by replacing Z80 processor. FPGA in board contains:

• Z80
• V9958 with hdmi output
• MSX2+ BIOS
• 4MB mapper
• RTC
• PSG through hdmi
• OPLL through hdmi
• MEGARAM-SCC through hdmi

How it works:

Logic acts on bus control signals so that internal devices inside fpga take priority over external devices.

Revision 2 Board

Revision 2 uses SOIC-20 for 74HCT373 and 74LVC245 ICs, which are smaller:

Slot map

Warning: not yet fully working on all tangs!

Tips:

• Get integrated circuits from trusted sources
• Use turned pins in header to avoid damages in Z80 socket
• Board is sensitive to dirty electrical contacts, way more than Z80. Keep cartridge & Z80 socket contacts clean
• Diode avoids hdmi plug from powering the MSX, but causes a voltage drop. If tang doesn't boot, bridge the diode and remember to remove hdmi cable when not using
• When soldering headers, start with the inner one (Z80)