Eugeny Brychkov created new firmware (addition) that enables the GR8NET to be compatible with the OPL4 as well.
Check out the video at: https://www.youtube.com/watch?v=HXmx8BeA1vY
You need to upgrade your general firmware to 0.12, flash another additional firmware for OPL4 compatibility and of course the YMR801 rom.
The version in "test-images" dated 2021-10-26 has a fixed issue about high pitched noise, it is highly recommended and also used in this guide.
Quick update guide:
• _FLINFO and check if you have the W25Q128FV chip (16MB). If you don't, you cannot use this firmware.
• Check if you have version 0.8 or higher using _NETVER. If you don't you first need to upgrade to 0.12 with a hardware flasher.
• _NETBROWSE to http://www.gr8bit.ru/software/firmware/GR8NET
• Press enter on "update.asc" to update everything to 0.12
• Power cycle (with cursor down pressed)
• Check if you now have version 0.12 using _NETVER
• Check your serial flash free sectors with _FLLIST
• _NETBROWSE to http://www.gr8bit.ru/software/firmware/GR8NET/test-images/
• Press enter on the "gr8net-fpga-reg.bin " image
• _FLUPDATE(0) (note: this updates the genenal0 firmware to a bugfixed version)
• Power cycle (with cursor down pressed)
• _FLLIST to list free sectors. You probably just have the MP3 firmware at sector 4, sector 8 and higher are free.
• _NETBROWSE to http://www.gr8bit.ru/software/firmware/GR8NET/test-images/
• Press enter on the "gr8net-fpga-opl4.bin" image
• _FLUPDATE(8) to write to sector 8 (or another free 4 sectors)
• _NETBROWSE to http://www.gr8bit.ru/software/firmware/GR8NET/OPL4ROM/
• Press enter on the "gr8net-opl4r.asc" basic program.
• The program will ask the free sector to write the OPL4ROM to. In the default state, this could be sector 12. It needs 32 free sectors).
Now you can switch to the OPL4 firmware using _NETRECFG(8). When booting press TAB to select the OPL4 mode (combination of Nextor, OPL4 memory and main memory). Option 3 selects Nextor, 512MB of main ram and 512KB of OPL4 ram.
Notes:
• The OPL4 firmware does not support any other hardware so all GR8NET basic commands are gone.
• Do not flash the OPL4 firmware to sector 0. You know, you GR8NET commands are gone.
• To get back to the default firmware, power cycle.
• If you want 1MB of OPL4 ram, select option 2 at boot, but you will need another device to boot DOS2 from.
• When using MAPDRV note the Nextor rom has moved from extended slot 2 to 0.
