It's kind of a pain to send a "printout" of an ASCII file to a vintage printer from a modern computer over the serial port. Here is how I sent a set of ASCII art prints to a Digital Equipment Corp Decwriter II. This technique would work with any serial terminal ("dumb" terminal), but you may need to change the settings to match your terminal/printer.
1. Find a computer with a real serial port. Did you know even today many PC motherboards have a serial port built in, even if you don't have an external port? You'd just need to find an internal serial port adapter. A true serial port is better than a "USB to Serial conversion dongle" in that using the real thing eliminates variables associated with converting the signal.
2. I used TeraTerm software from the PC. From TeraTerm locate the setup tab. There are two places you need to access to make changes
a. serial port setup (set to match your printer or terminal, these are the Decwriter II settings...)
COMx (where x = 1,2,3,or 4 usually)
baud = 300 (or whatever yours does)
hardware (may not be necessary)
b. terminal setup
transmit = cr+lf
3. When you send your ASCII file, make sure binary is unchecked.
4. Cable - Use a null modem cable.
See you at VCF East!