XC4000E pdf,XC4000X datasheet

XC4000 Series devices are implemented with a regular,
flexible, programmable architecture of Configurable Logic
Blocks (CLBs), interconnected by a powerful hierarchy of
versatile routing resources, and surrounded by a perimeter
of programmable Input/Output Blocks (IOBs). They have
generous routing resources to accommodate the most
complex interconnect patterns.
The devices are customized by loading configuration data
into internal memory cells. The FPGA can either actively
read its configuration data from an external serial or
byte-parallel PROM (master modes), or the configuration
data can be written into the FPGA from an external device
(slave and peripheral modes).
XC4000 Series FPGAs are supported by powerful and
sophisticated software, covering every aspect of design
from schematic or behavioral entry, floor planning, simulation,
automatic block placement and routing of interconnects,
to the creation, downloading, and readback of the
configuration bit stream.
Because Xilinx FPGAs can be reprogrammed an unlimited
number of times, they can be used in innovative designs
where hardware is changed dynamically, or where hardware
must be adapted to different user applications.
FPGAs are ideal for shortening design and development
cycles, and also offer a cost-effective solution for production
rates well beyond 5,000 systems per month. For lowest
high-volume unit cost, a design can first be implemented in
the XC4000E or XC4000X, then migrated to one of Xilinx’
compatible HardWire mask-programmed devices.