The e8051 has these features:

* 100% instruction set compatible with standard 8051 and 8052 microcontrollers.
* Fully synchronous single-clock architecture (for one cycle instructions, Mips rate = clock rate).
* Very high clock rates.
* 256 registers and 64k program and 64k data space - easily expandable.
* Full standard peripheral set including 3 timers and 2 serial ports.
* Users can add their own ports and peripherals.
* Four-clock and one-clock timer-counting-modes as well as standard twelve-clock mode.
* Two standard data pointers (DPTR and DPTR1).
* Full set of 24 separately vectored interrupt sources.
* Low gate count/cell count - as low as 700 CLBs in Xilinx Spartan FPGAs.
* Synchronous design suitable for high-coverage scan test.
* Low power consumption.
* Low cost (see prices).
* Full-speed evaluation netlist available for developing small test programs on any platform.

but that one intended for ASIC claims it's 8.1 times faster than the standard 805x at the same crystal frequency. The SiLabs 'F12x's and Maxim/Dallas DS89c4x0's are certainly capable of more speed. In fact, any one-clocker at 25 MHz is as fast as that one at 300 MHz, at first glance. Not very impressive!

RE