Connecting an old reel-to-reel tape deck to a computer lets you create a copy of old analogue audio tapes and store it in a more convenient form on your computer. You can even burn the recording to a CD at a later time, if desired, to make those old reel tapes portable. Connect the equipment using a standard stereo cable with RCA-type plugs on each end, plus a Y-shaped audio adaptor to condense the two cables from the tape deck into a single stereo mini-plug to connect to the PC.
Turn off the power switch on the front of the tape deck.
Connect the red and black plugs on one end of the stereo cable to the right and left playback/audio out jacks on the rear of the deck.
Plug in the other ends of the cable to the two jacks on the Y-adaptor.
Insert the stereo mini-plug on the Y-adaptor into the computer's "Line In" jack, which is on the back of the tower. Use the "MIC" jack on the edge of a laptop.