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
- SCC (audio only) through hdmi
Logic acts on bus control signals so that internal devices inside fpga take priority over external devices.
Mind Revision 2, 4 and 4.1 uses 74LVC245 in U5. Although their technical information tells they require 3.3V to operate, they are also 5V tolerant. This has been tested and considered safe. Check #15 for more information. Revisions 2, 4 are outdated and kept for reference only.
Revision 2 uses SOIC-20 for 74HCT373 and 74LVC245 ICs, which are smaller:
Revision 4 uses TSSOP-20 ICs, to get an even smaller footprint:
Mapper can be relocated to slots 1, 2, or 3 using config menu.
- Replace U1, U2 -> 74HC373, U5 -> 74HC245
- Solder a 10K resistor array to data bus lines, pulled up to 5V
SCC is located in Slot 0-2 to use with sofarun, using these settings:
Config menu is showed pressing g during MSX logo. New improved menu is created by nataliapc
- Enable Mapper: On by default. Disable when having compatibility issues or to use a different mapper
- Mapper Slot: 0 by default. Change to 1-3 to get mapper in a not expanded slot (best compatibility). Physical slot will be disabled
- Slot 1 Ghost SCC: Off by default. Enable to get sound from an SCC cartridge located in slot 1
- Enable Scanlines: On by default. Disable to get a clean hdmi picture
- Save & Exit: store new config and continue, changes in mapper settings will be effective after pressing reset
- Save & Reset: store new config and make software reset, changes will be immediate
Goa'uld has four internal slots available. As with other modules, internal slots take priority over physical ones. This means that when a device is using internal slot n, then physical slot n is disabled and any cartridge in that slot will not be detected. By default, BIOS and mapper occupy internal slot 0, leaving physical slots 1 to 3 available for cartridges. However, this default layout can cause compatibility issues with some software, such as tape games. To resolve these issues, you can move the mapper from expanded slot 0 to one of the non-expanded internal slots (1, 2, or 3). This adjustment can solve many compatibility problems.
- Reset from config menu is not compatible with some hardware. Use physical reset button when possible
- Multimente: shows garbage characters. Move internal mapper to slots 1, 2 or 3
- Tape games fail: move internal mapper to slots 1, 2 or 3
- Noises when loading a rom with sofarun: change sofarun settings to use mapper for that rom
- Carnivore C2 software reset is not compatible with goa'uld
Warning
Not yet fully working on all MSX!
- Get integrated circuits from trusted sources
- Use a heatsink when possible
- 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
- When soldering headers, start with the inner one (Z80)
