Someone stated that the communication speed is currently about 160 bits per second, so 20 bytes per second.

Voyager is now 1 light day away, so the signal is 86400 seconds long, since radio waves travel at the speed of light. The signal can then fit a backup of 1.7 megabytes.

20 bytes x 86400 seconds = 1.7 Mb (SI units)

This is enough to fit the entire memory bank of 26 Commodore 64s in a one way trip from the Earth to Voyager. If Voyager then returns the signal, you can simply double this.

So about 2 floppy discs. 💾 💾