The only problem I have with the AVRs emulation is that what the emulator sees from your circuit is not necessarily what the production chip will see. Scenix and (I think) the Micro Chip ICD avoid this.
I don't know their approach, but certainly any emulation is not going to be identical to the production, or else every production device would have to contain an emulator.
But that, my good friend, is EXACTLY what Scenix did! Every production SX has the emulator circuitry embedded in it! It uses a serial interface to an adapter (the SX-Key) that controls the production device from the inside to implement single stepping, port pin reading, breakpoints, etc... ...and its pic code/speed compatible or can run with a pipeline at 50MIPS. Comparable prices, lots of Virtual Peripheral source code for all the common stuff that slower processors have to implement as external hardware like high speed UARTs, MODEMs, IRDA, DTMF i/o, Caller ID, high speed IIC or SPI master or slave, micro second timers, frequency detection on any frequency from 100Hz to 13/1kHz that the SX can implement with only a few discrete components. Now before somebody yells at me for touting Scenix on the PIC list: They only have 2 chips in production (1.5 port and 2.5 port, 5 port SX52 on the way (I have one)), the IDE uses funky parallax mnemonics, and they are the sole source. Scenix is to MicroChip like Zilog was to Intel back in the 8080/Z80 days. James Newton, webmaster http://get.to/techref (hint: you can add your own private info to the techref) mailto:jamesnewton@geocities.com 1-619-652-0593 phoneÊ