FS: Factory original, still in the wrap, Tektronix TDS Family Digitizing Oscilloscopes Programmer Manual; for models TDS 410/420/460/520A/524A/ 540A/544A/620A/640A/644A. $22.50 + actual USPS shipping charges email replies, tnx in advance barry carson city, nv http://home.att.net/~btuttleman2/electron.html