What is Half track and quarter track?

AS @audioguyintn explained, a 1/2 track machine records and plays back 2 channels in one direction. There is no "other side" You have to rewind it. My father had an interesting machine. It was a 1960ish Ampex 1/2 track that took only 7" reels. It would record and play back 1/2 track but it also would playback (but not record) 1/4 track. In the day they sold 7" prerecorded tapes in 1/4 track at 71/2 ips. There was no Dolby back then and just dropping to 31/4 ips was intolerably hissy. You played them just like a record. One side and then the other. This made skipping songs very difficult. You had to hunt for them in fast-forward or reverse. A record you just place the "needle" were you want it. Playing a 1/4 track 71/2 ips prerecorded tape back then was way superior sonically than any record playing set up. You just got use to that hiss.

1/4-track and 4-track ARE NOT THE SAME.

Veteran professional recording engineer of 40 years.

1/4 track is two tracks using one half the tape width for a pass in one direction.

4-track is 4 tracks using the full width of the tape for a pass in one direction

Most 4-track machines can play 1/4 track content, but will be playing both passes in one direction, so that the 3 & 4 tracks are being played "backwards"

1/4 does not equal 4, just as 1/3 does not equal 30%.  Sound similar, not same.

Mitch, the machine you are referring to was when 4 channels were in vogue. I had a Phase Linear 4000 preamp that was 4 channel. The recorder you had could record 4 channels in one direction. It was called "Quadrophonic".

The Technics RS1500 series was a quarter inch, two track machine for recording and playback. However, it also would play 4 track tapes via a switch on the head block. Great machine and is the choice for Tape Project restorations.

Hifigy, I didn't see dualhead Studers, Revoxes or Tandbergs on ebay. This must be custom version, I suppose.

Quarter track allows you to record 4 tracks on a quarter inch tape or two stereo tracks in both tape directions. Half track literally divides the quarter inch tape in two. A wider track and all things being eqaul, beter signal to noise due to a wider track but, you can record in only one direction unless you have a need for half track mono. Many decks especially pro units had both a quarter and half track head and allowed switching between heads depending on the tape being played back.

A half track used the entire width of the tape to play or record; a quarter track used half the width of the tape and so would play or record in both directions. So half track used twice the tape quarter track did. All prerecorded tapes I ever had were quarter track; half track was for pro use or serious amateurs. They are the same as two track and four track, half track means that it used half the tape to record one channel and half the other, so it was called two track. Quarter track used 1/4 of the tape to record one channel of the music, you went to the end and then reversed the tape to get the other two tracks. So quarter track and 4 track are the same.