Added a UART to the Z80

I added a UART to the Z80 board. The original thought was to use a PIC on a separate board to do the UART function but the PIC wasn't quite fast enough. I ended up using a TL16C550 from Texas Instruments and along with a Microchip MCP2200 UART to USB chip. I've used the MCP2200 many times before as finding a 9 pin RS232 COM port on a PC is getting hard these days. I've been able to get UART input and output at 115.2KBaud with no issues.

Z80 CPU with UART Schematic