Overview

Getting files onto an old computer is the hard part — floppies rot, serial cables are fiddly, and most vintage machines can't talk to modern networks on their own. A wifi modem (such as the WiModem232 Pro) solves the networking side, but the old machine still needs something on the other end of the connection to serve the files.

XFER is that something. Run it on your modern computer, then from the old machine's terminal program "dial" into it over the wifi modem: browse the modern computer's file system, view files inline, and download any of them to the old side using XMODEM, ZMODEM, or Kermit.

Features

How to get it

Download the suitable executable for your operating system from GitHub and save it on your hard drive.

Usage

1. Start XFER on your "modern" computer: When running xfer, you probably don't need to change any options, but you can use the -h command line switch to see what options are available:

$ xfer -h
xfer v1.2.2 — XMODEM / ZMODEM / Kermit file server + viewer for old computers

Usage: xfer [flags]

-p, --port <number> port to use (default: 23)
-d, --directory <string> directory to serve (default: current directory)
-s, --secure secure mode: don't allow user to change directories
-n, --no-url disallow the [U]RL download option in the file listing
-c, --no-stdin-url do not inject stdin lines into a client's URL prompt
-w, --wirelog <path> hexdump every wire byte to file ("-" for stderr)
--term-width <n> default/fallback terminal width (default: 40)
--term-height <n> default/fallback terminal height (default: 20)
--no-term-detect skip terminal-size auto-detection on connect
--term-detect-timeout <ms> how long to wait for the probe reply (default: 2000)
-V, --version print version and exit
-h, --help print this help and exit

Note: the default port is 23 (telnet), which on most systems requires administrator/root privileges to bind. You'll most likely want to pick a higher port instead, for example 2000:

$ xfer -p 2000
2026-04-22T12:15:30.123Z Server now listening on 192.168.1.194:2000 / 10.0.0.5:2000

2. On your "retro" computer, use terminal to connect: we're using the Hayes AT command to "dial" into the host computer's IP and port:

ATDT192.168.1.194:2000
Detecting terminal size...
Terminal size: 80x25
----- /Users/arttu/games -----
1 <D> ..
2 ... paradroid.prg
3 ... mule.prg
4 ... wizball.prg
1-4, [U]RL, [S]earch, [R]efresh, e[X]it: 3
Ready to download mule.prg
Size: 48829 bytes
MD5: 9a982e21160b982a02fd43412f14e127
/Users/arttu/games/mule.prg - [X]MODEM, [Z]MODEM, [K]ermit, [V]iew, or [C]ancel?: Z
Initiating ZMODEM transfer for /Users/arttu/games/mule.prg
Please start your ZMODEM receiver NOW.

Size and MD5 are shown before the protocol prompt so you can see how big the file is before picking a protocol — XMODEM is fine for small files, ZMODEM is much faster on larger ones.

For ZMODEM, most terminals (Term 4.8, NComm, SyncTerm, etc.) auto-detect and start receiving. For XMODEM and Kermit you need to manually trigger the receive in your terminal program.

You can also browse the host computer's file system (unless you start xfer with "secure mode" which allows you to only browse files and not to move to another directory).

Terminal size auto-detection

On connect xfer sends a standard ANSI cursor-position probe (ESC[6n) and uses the terminal's reply to pick a size for the directory listing and the file viewer. Most modern terminal emulators answer in a few milliseconds; vintage terminals over a wifi modem (Term 4.8 on Amiga, for example) take ~1 second. xfer waits up to two seconds and then either prints the reported size, or falls back to the configured defaults (40x20 unless overridden with --term-width / --term-height).

On a terminal that doesn't understand CSI escape sequences (e.g. a plain PETSCII terminal on a C64), the probe bytes echo as a few literal characters on screen — the leading Detecting terminal size... line is there to frame those characters as detection noise rather than unexplained garbage. Skip the probe entirely with --no-term-detect if you're connecting from a terminal that mis-handles the escape sequence.

Listing big directories

When a directory has more files than fit on one screen the listing pauses with [M]ore, [S]earch: after each page. Press M to keep paging, or S to filter — type a substring and the listing redraws as just the files whose names match (case-insensitive), preserving the original entry numbers so the digit you type at the menu still picks the right file.

Downloading from a URL

You don't have to pre-stage a file on the host's disk. Press U at the listing to type a URL; the server fetches it over http/https, shows the size and MD5, and hands off to your pick of XMODEM / ZMODEM / Kermit (or the viewer). The body is kept in memory — nothing is written to the host's disk.

Type the URL on whichever keyboard is convenient. Long URLs are miserable to type on a retro keyboard, so once the URL prompt is up you can enter the URL on either side — the old computer's terminal or directly into xfer's console on the modern computer (paste or type, then press Enter). Whichever side hits Enter first wins, and the characters echo on the old computer's screen as if typed there.

Disable URL fetching with -n / --no-url: a connected client can otherwise ask xfer to fetch any URL the host itself can reach — including machines on the host's private LAN that the client couldn't normally see.

File viewer

Instead of downloading a file, pick V at the transfer prompt to view it inline. The viewer auto-detects text vs binary and picks char or hex display accordingly. Single-keystroke controls (no arrow keys needed):

f / b — scroll one line forward / back
d / u — scroll one page down / up (SPACE = d)
m — toggle hex / char display
s — search; empty input repeats the last search
q / c — quit back to the file list
h — show help

THAT'S IT!

Enjoy! If you want more details, visit the GitHub page.