This is correct, the code is stored into U44 and U45
There are also some dynamic data (mainly lifetime audits).
Quoted from fly:
if I could somehow download flash boot rom ??
I'd try even record a new rom on eprom
U9 is the boot prom that holds the USB loader :
- When SW1-8 is ON, the game boots on U9 (and U44&U45 are only used to store a new firmware - no code is running from here)
- When SW1-8 is OFF, the game boots on U44&U45 (and U9 is not used at all)
As your game is still not working with the prom, that probably means that U44&U45 are not the issue.
Another component is involved.
What are the behaviour differences when SW1-8 is ON or OFF (reboot after you change it) ?
Is LED3 blinking (located 2 inches above the dip switches) ?
How is the watchdog LED on the IO board near the Reset indication (just under the 3 big capacitors) ?