A 50-MHz EZ80F91 processor module featuring 256 kbytes of flash and 16 kbytes of SRAM can be found in the Z80F91 Modular Development Kit. The module has a 10/100 Ethernet interface, real-time battery-backed-up clock, and expansion connectors. There's also room for an optional SIR IrDA interface. Modular Development System software includes its own TCP/IP stack. The kit costs $99.