Though you may not want to do it, it's a good thing to become familiar with and fluent in CPLD's before FPGA's. They're quicker and easier to implement, cost less, and come in packages you can actually use. A schematic can easily be implemented in a CPLD. All such bets are off where FPGA's are concerned. There are many things you can't easily accomplish in CPLD that become quite straightforward in FPGA. Moreover, you can often enhance the capabilities of an FPGA implementation with a little CPLD outside. In CPLD's, you have lots of logic associated with every flipflop, i.e. they're logic-rich and register-poor. FPGA's OTOH, are logic-poor, in a sense, yet register-rich. Pinouts in CPLD's are essentially fixed, at least after the first time you fit a design, and timing is deterministic. Pinouts in FPGA's often have to be changed in order to accomodate timing constraints, and rerouting often forces pinout changes. Wide gates in FPGA tend to end up being relatively slow because they're built with concatenated lookup tables. That requires addded routing delays, though they're short. There's a lot you can learn by playing with these, but if you want to get a job done today, FPGA may not be the best way.

As for the 8051 core and an evaluation board that might suit your purpose, what you'll want is a kit that has as little on it, asside from the FPGA, a boot PROM, and maybe a level shifter for serial comm's, as possible, but with an FPGA that has enough block RAM so you don't have to attach an external ROM. In that case, you won't need a prototyping area either, though I'd look for a board that has a HUGE FPGA (that's the only way to have at least 64KB of code space and 64KB of XRAM space, in addition to the 256 bytes of internal RAM for the 805x. Just make sure that the software you intend to use has the ability to develop/program the FPGA you use.

Development/evaluation boards tend to have too much rubbish on them, and, most of the time, that rubbish can't be disconnected from the FPGA, so you can't practically use those pins. In fact, most evaluation products are completely useless for anything practical at all. They have "stuff" on them that serves no useful purpose, yet they have no means for "getting rid of it" such as jumpered connections. Many boards have SDRAM and FLASH on board, yet have no means for using it, and, if you do manage to use, say, the SDRAM, you have lots of memory, but no internal resources with remaining with which you can use it.

If 805x-core development is all you hope to do, then you needn't be too fussy, but if you also want to mess with NIOS or MicroBlaze, for example, you need about 8 MB of FLASH and 16MB of external SDRAM for purposes of being able to run an OS. Don't expect anything useful from the "VGA" ports some boards offer, unless you're developing a graphics adapter. Unless they have a 3-color DAC on board, VGA is a pipe-dream. Some of them contain PS/2 connectors. Unless you know you're going to need that, stay away from those boards, as they, again, interfere with useful things for which you might use them.

If possible, try to get a board with no displays, no LCD, no switches, etc, unless they can be removed with jumpers and have the signals routed to a connector by means of which YOU can route the signals to a prototype area. I emphasize this because many boards have costly, fragile, and difficult-to-use connectors that you have to buy in hundreds and have to wait a long time to receive them.

If the board you decide you want has a connector, be sure to order the prototype board that mates with it right away. You never know when they'll suddenly become unavailable.

If you buy a board that's sold by XILINX but made by Digilent, then it's sometimes better to buy it from XILINX because they provide things that Digilent doesn't. Read the fine print! Be sure the features you expect are actually included and installed. Carefully examine the documentation. Often it's incomplete. If it's incomplete, it will likely stay that way.

Forewarned is forearmed.

RE