<FYI, yes, the 780 does have writable control store.  At least, its listed 
<(and drawn) in the schematics...  from memory, I'm pretty sure it was not 
<just an option... but I could be wrong.   Not sure if the WCS was loaded fr
<the LSI-11 front end or whether it was loaded by the OS once running...  

Exactly the use.  Proms of the time were too slow fo rhte numebr needed and 
uCode was a bit unstable and tuneable as well so making it writeable was
a good fix but not cheap.

The 700 series in general use writeable ucode stores (780, 782, 785, 
750 and 730 to be sure I may have missed a few).


Allison