[pastera]

Where will you put all the memory you will need to hold the G-code?
FPGA's are extremely expensive when compared to a general purpose processor (8051). If a microcontroller can do it, and it can, then it would be cheaper to place the bulk of the processing in the uC and use one or two CPLDs for the high speed logic that the processor can't handle.

Aaron

[Episs]

I will use parallel flash memory 32Mb (16bit) atmel AT49BV322
I think 32Mb would be enough for G-code and procesor code storage.
About processors then they are not so cheep as compared to FPGAs for example Atmega128 is about 16$, we can take more powerfull AT91SAM7xx ARM7 core about 11-12$ and all they have is Flash memory that my FPGA don't have and Fpga costs are: EP2C8F208C7 20.3$ in digikey +configuration Flash (there are lot of options we can use EPCS4 (16$) or some simple MCU like Atmega48 1.5$+SPI cheep Flash 3$=4.5$) so totaly working FPGA in cheapest configuration will cost about 25$ and it is just 2X more than single MCU but in FPGA we can put 3 Mcu cores (like Nios II) + logic so we get higher price/perfomance ratio. Actualy there is one cheep FPGA motion controller it is MesA FPGA anything IO card but I need sutch electronic which I could modify by my needs and with more logic capacity.
And FPGA is more flexible and If wouldn't like Nios II core then I can downlode any other core and reconfigure fpga so I can evaluate diferent free IP-cores and choose the best for my design. This reconfiguration feature is what I need.