Maybe it is a rebranded 6802/6808? There is a crystal located around pin 38+39 where you should expect this for a 6802. There is a resistor network where the pins for the databus are located (pins 26-33); these resistors might be used as pull ups for the databus. Take a look at the datasheet for the 6802 and locate the pins for +5V ( pin 8 ) and Ground (pins 1 + 21) and see if they match. Is there a NVRAM used? You can test for continuity from the R/W line from the NVRAM to the pin where you expect R/W for a 6802 (pin34).