On Wed, Mar 04, 2015 at 06:29:34PM -0600, Jim Brain wrote: > I am not disputing that they are different, I just cannot understand why > CSG would have taped out a simpler version of the 6526/8521 when they > already had a die for the 6526. 6526 and 852x are very different. > I can understand doing the work needed > to move the 6526 into HCMOS II, but why not go straight to the 8521, so > the resulting part could be used for the 64c/128/1571/1581/etc. > > It just does not make sense. It's like saying: I am going to modify my > iOS app for iOS8 and I am going to remove some key functionality, and > retest the entire app, since that functionality could affect any part of > the app. > > There has got to be more to this story. I don't buy that the TOD BCD > stuff took up that much die real estate, and so I can't believe that the > removal would have improved yield considerably. About half of the 8521 layout is wasted space anyway; space is not the issue. The 8520 has a TOD just fine as well -- but a binary counter, not a BCD counter. A BCD counter does not take up much extra space, either. Presumably they just wanted a binary counter for the Amiga. The idea that they made the 8520 and then the 8521 was an afterthought might be true, too :-) Segher Message was sent through the cbm-hackers mailing listReceived on 2015-03-06 16:00:07
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