Black Jack has now been dumped and a PR has been added @JustDesserts: Thanks for supplying the game!
This game is interesting as it is based on the SM512 and also has never been simulated or emulated before AFAIK. The game displays has lots of segments (199 in total) and is therefore utilizing almost all of the 200 possible segments available on the SM512. The melody ROM has been dumped electronically in the same manner as for the Climber game and been marked as a BAD_DUMP.
The input controls has been mapped to joysticks (left joystick up/down and right joystick up/down). Perhaps it would have been better to instead use the IPT_GAMBLE_* IO-ports? Please advise me if you think this should be changed.
Also, I just noticed on the MW forum that hydef has released artwork for all G&W games supported in MAME except for one. Check them out as they are awesome!