> The "FIXED BITS" message is not at all mandatory. It's just a helpful diagnostic
> produced by MAME's romcmp tool, which can only catch a few types of common dumping
> errors. Depending on the hardware, some romcmp errors might not even be errors:
> oversize ROMs are common and graphics ROMs and bipolar decoding PROMs might not need
> all the data outputs that the part has.
>
> A few types of dumping errors romcmp can't detect but have occurred:
>
>
> One or two bad bits (as in Sky Army).
> Fixed bits that extend only through certain areas of the dump. (I've patched a few
> cases of this by hand.)
> Bridges between address lines that cause 3/4 mirroring (as happened with the Eeekk!
> color PROM).
> Faulty internal latches on 8048, 8041 or related MCUs.
doesn't detect combinations of data lines shorting each other out either (which happened on a recent dump from Sean, that I thought was encryption at first)
|
Previous 
Index 
Next 
Flat 
Re: skyarmy and rom FIXED BITS curiosity
Reply
