What kind of IC is this

[Tony Duell]

> 
> On 30 Dec 2008 at 22:30, Oliver Lehmann wrote:
> 
> > But right now I just care about backing up all EPROMs and PROMs from this
> > system here just in case something happens... (and the 6306's are now
> > backed up as well :-)
> 
> Do fusible-link PROMs go bad?  At least do they go bad any more often 

_Any_ device can fail. Fusible link PROMs can suffer from a form of 
bit-rot where the links actually grow back as well.

> than some of the LSI on that board? (Okay, I don't know what's on it, 
> but I assume some sort of bit-slice implementation).

Well, having a backup of the PROMs is surely a good idea for 2 reasons : 

1) If the rest of the board is standard parts (even if they are failry 
rare ones), then shoulc something fail you have a chance to get the 
replacements. If it's one of the standard parts, you can hunt for 
another board that used it (not necessarily from this machine), if the 
PROM fails, you can burn a replacement.

2) Even if there are custom LSI parts on the board, then having a ackup 
of the PROMs means you can fix it if the PROMs go bad. Even if you can't 
do anything if the LSI device fails, you can fix some faults.

-tony