A History of PowerPC 193
A reader writes: "There's a article about chipmaking at IBM up at DeveloperWorks. While IBM-centric, it talks a lot about the PowerPC, but really dwells on the common ancestory of IBM 801" Interesting article, especially for people interested in chips and chip design.
*sigh* (Score:3, Insightful)
Nice 42 year backward compatibility (Score:5, Insightful)
John.
Power PC was the death of the MIPS processor (Score:4, Insightful)
Gone where the intelligent disk and network subsystems. No more die cast aluminimum chassis.
Whilst I can understand in some sectors the incessant drive for highest MIPS per $, is there not also a place for bullet proof proven technology?
Computer history IS IBM-centric (Score:5, Insightful)
200 instructions at once? (Score:5, Insightful)
(Which is great until you mispredict a branch, of course. :-)
I like this quote (Score:5, Insightful)
Can anyone tell me where I can buy a G5 laptop?
Don't ignore integer sizes! (Score:5, Insightful)
So, you're reading in an array of integers, which are now 64 bit vs 32 bit and no code change is needed?
Programs NEED to know the size of the data they're working with. Simply pulling data from an address without caring for it's size is a recipee for disaster!
that's not what RISC really turned out to be (Score:1, Insightful)
So, to do this, you drop specialized functionality. This meant simplifying the instruction set.
But that produced code bloat, because to really follow the idea you have to ditch stuff like dividers. Dividers are very difficult to fit into a pipeline and so the proper way to follow the mantra is to to expand a division into 32 separate instructions that do one step of the process (or 17 stages with other dividing methods). These 32 instructions could be pipelined, and thus you maximized your transistor reuse.
But this leads to code bloat. At the minimum, you have to do some call setup and takedown to call a division function. So that hardware was put back in. And other hardware followed, until even specialized vector units are allowed.
CISC can produce good performance also if they can utilize all their transistors better.
Re:Yeah, I remember (Score:3, Insightful)