On Apr 19, 11:51, Douglas H. Quebbeman wrote: Well, if you're going to go into digital signal processing, why not just use a 9-track head, and analyse the data from adjacent tracks to recombine into 7 tracks? ;-) I'll bet it's doable. My second-year second-term (10 weeks) assigned project was to build a barcode reader, using a common slotted optosensor with an active area whose diameter was about twice the width of the bars, and a Z80 with 2K EPROM and 8K RAM. It's amazing what you can do with a little circuitry and a little calculation. 9 tracks to 7 should be easier, since I expect the top, bottom, and middle tracks will line up nicely. The second track from the 9-track head would have a mixture of (mostly) 1st and (a little) 2nd tracks of the 7-track signal; the next channel would have a roughly equal mixture of data from tracks 2 and 3; the next channel would be almost all 3; and so on. -- Pete Peter Turnbull Network Manager University of York