Part 1: using a retro computer as a terminal

 

How to get retro computers online in 2025 using only a £12 cable (and a smartphone) - part 1

Overview

The Cable

You will need a USB-C to RS232 cable. Mine came from eBay and cost £12. It uses a Prolific PL2303 (probably fake). You also need an Android phone with a USB OTG port.

Connecting to the phone

Plug one end of the cable into your phone and the other end into your retro computer's RS232 port or adapter. Android doesn't have any drivers for serial ports, so we will need an app to connect to the cable - I used TCPUART. Set your cable speed to 9600 bps or whatever your retro computer can handle. This app can't enable hardware flow control, so you are going to have to start slow.

Connecting to a terminal. 

You need a terminal server at the other end. TERMUX is a Linux emulator for Android phones. It doesn't need root access, just a port to listen to. I will choose port 8000.

To connect a Termux terminal to the TCP Server, use the Unix utility socat to bind a terminal to the chosen port:

socat exec:'bash -li',pty,stderr,setsid,sane tcp-listen:8000,bind=localhost

Now Ccnnect the TCPUART app (as a client) to the same address and port (127.0.0.1:8000).You can now use a terminal app on your computer to connect. On my Psion, I use Hermes to emulate a VT100.

Socat will create a pseudo-tty for bash, so you can set up bash to use this:

stty rows X cols Y 
export TERM=vt100

now go ahead, and use any command-line apps you fancy. I recommend the links web browser. 



For file transfer, you might want to check out the lsx utility for xmodem, or lsz for zmodem, whichever your terminal client supports.

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