The Processor

The Casio Cassiopeia E-125 is powered by a 150MHz NEC Vr4122 MIPS RISC processor. On the right is a picture of the processor.

The NEC Vr4122 processor is actually just an enhanced version of the Vr4121 processor used in the older E-115 Pocket PC. Although the data and instruction caches were doubled in the Vr4122, the processor core remained basically the same. So, you shouldn't expect any significant boost in performance.
   

Surprisingly, NEC states that the Vr4122 scored 216 Dhrystone MIPS at 180MHz while the older Vr4121 scored 210 Dhrystone MIPS at 168MHz. That means that the Vr4122 is actually slower than the Vr4121 at equivalent clockspeeds! If so, then what advantages does the Vr4122 have over the Vr4121?

The most obvious are the higher clockspeeds. The slowest speed grade is 150MHz although the Vr4122 can run up to 180MHz. The Vr4121, however, is only rated at 131MHz and 168MHz. As Casio uses only the slower speed grades in their Pocket PCs, so the E-125 has a 14.5% (19MHz) advantage in clockspeed over the E-115. We will see later if this increase in clockspeed actually translates into an equivalent increase in performance.

The main advantages of the Vr4122, however, are lower power consumption and thermal dissipation. Even at a 7% higher clockspeed, it consumes only 270mW, compared to the Vr4121's 350mW. That's a saving of nearly 23% which will translate into less heat dissipation and longer battery life. This is all due to the thinner fabrication process used in the Vr4122 (0.18 microns instead of 0.25 microns).

Kujira?

While checking out the PCB of the E-125, I noticed another major chip labeled as the Casio Kujira. I found no documentation of this chip but it's most probably the companion chip for the Vr4122 processor.

The companion chip handles all analog-to-digital and digital-to-analog conversions. This includes translation of any input using the touch panel as well as audio output. It also provides support for the CompactFlash slot.