HP Prime use ARM 9?

[cyrille de brébisson]

Hello,

Prime does indeed use an older ARM9 based design.
ARM9 have been the workhorse of the ARM familly until the exponential growth of smartphones caused them to create the newer Cortex series...

The Cortex M series are kind of the successor to the ARM7 series. A Cortex M4 is now used in the 12C and replaces an older ARM7TDMI...

The Cortex A series replaces the ARM9 series (A stand for 'application'). The main difference from a feature point of view is that the A series have a MMU while the M series do not.

A series chip commes in all flavours and speed and have had their own generations...

The main differences are speed grades, 32 or 64 bit and, number of parallel ALU and pipeline depth.

Add parallel ALU and pipeline depth and you can run faster and do more at the same time. But the cost is increased complexity and power use.
Decrease them and the CPU is simpler, consumes less, but can not perform as fast frequency wise and can not do as many things at the same time...

Then you have core count, cache and periferials in the chip...
More core = more stuff you can do in parallel. However prime is realy much more of a single thread system, so there is no gain in paralelism there.
More cache = higher speed as there is less RAM access needed. It also decrease power use because RAM consume power to access.
Periferials can include things like GPU which are usefull for mobile phone (because that it all we need; 3D on a phone!!!!) but also much more important stuff like IO pin managers and LCD drivers...

Should one design a calcualtor at the moment, a Cortex A7 would be a good choice. low power, but still significantly better than the ARM9. Cheap and plentifull enough. You can find such CPU in low end phones/tablets... and apparently in high end graphical calculators...

Cyrille