A small update
It’s been a while since I’ve done any work on this project. I was going to build, or at least part build a second board to see if I could get the V9990 working but I decided to get a new PCB made with some fixes for the issues that I ran into building up the current board.
In addition to the fixes I added an a SN76489 sound chip alongside the YM2151 to allow some additional sound effects, made a small change in the joystick ports so I could use Sega Mega Drive controllers and changed the Ethernet controller chip.
The changes were made at the start of the year and I’ve had the revised PCBs since the end of January but haven’t had the time to start build one up. Now that we are all on lockdown it seems that I’ve got some free time, so it seems like an ideal opportunity to get back to working on this project.