Last week I bought a new Z80 homebrew computer from Ebay. Its a Z80 based single board computer with 128KB RAM with some optional modules such as a RTC, GPIO expander and SD disk emulator and runs BASIC and CP/M.
Normally I buy these as kits which you solder together yourself. This one came already assembled with FTDI cable and a preinstalled SD Card.
It arrived via signed-for Royal Mail delivery in a small plain brown box. The components inside were sealed in ESD bags and there was a sheet of paper with some brief useful information. I took the computer PCB and carefully attached the SD card and RTC modules. You have to insert the SD card and a CR2032 battery for the RTC. Finally connect the FTDI cable being careful to orient the cable properly to prevent damage.
Once connected to a USB port on a PC, the device shows in device manager as a Silicon Labs CP21-x USB to UART Bridge (COM7)
Use a terminal emulator like Putty. Connect on a COM port (7) and select the baud rate 115200, click open