RetroBox is designed to work with both modern and vintage computers, but the physical connection is different depending on the machine.

Modern systems can use USB serial directly, which makes development and testing straightforward.

Older computers usually expect a real serial interface, so RetroBox also supports RS-232 through a MAX3232 level converter. That allows the modem to present proper serial voltage levels to vintage hardware without changing the way the computer expects to communicate.

The basic idea is deliberately simple:

Vintage computer → RS-232 → RetroBox → WiFi → BBS

The computer only sees a Hayes-style modem. It sends AT commands, dials a destination and receives familiar result codes such as CONNECT and NO CARRIER. Everything involving WiFi, TCP and Telnet happens inside RetroBox.

I have already tested working prototypes with 486 and Pentium-era PCs, and the same firmware can also be used from modern computers over USB.

One of the next areas I am continuing to refine is compatibility with more vintage platforms and serial adapters, while keeping the modem itself as universal as possible.