2-1. The Hughes MEMO »SCOPE Oscilloscope, Model 105 A, is an advanced laboratory-type instrument designed to test any type of equipment where performance can be translated into an electrical signal. The instrument is built around the MEMOTRON storage tube, which permits use of the oscilloscope as a storage-type instrument of long persistence, or as a conventional high-speed oscilloscope. In the storage mode, the MEMO-SCOPE Oscilloscope affords a visual presentation of all pertinent phenomena related to the equipment under test, including transient traces which are difficult or impossible to measure by other means. Traces remain visible at uniform brightness indefinitely, without fading or blooming, until intentionally erased. Successive writings may be superimposed or shifted in position for convenient comparison. Resolution up to 20 adjacent written lines per inch permits excellent interpretation of complex patterns. Reference lines can easily be stored on the face of the MEMOTRON tube as an aid in making accurate measurements. Traces that exceed the maximum writing speed of 1,000,000 inches per second in the storage mode can be visibly displayed by repeated retracing at repetition rates sufficiently high, to permit cumulative storage. These unusual features simplify test analyses and facilitate initial design of equipment by revealing hidden factors which affect performance. Wide bandwidth permits detailed examination of complex waveforms, A delay network insures presentation of all the incoming signal without loss of leading edges. Precision circuitry throughout the instrument affords a high level of accuracy in making measurements. Power supplies are connected to critical components in a manner providing adequate protection in the event of component failure. The storage circuitry has been designed to minimize the possibility of damage to the storage surface of the MEMOTRON tube in event of accidental operator error. Major circuit boards are mounted on hinged frames, all components are easily reached for servicing. Filtered forced-air cooling prevents overheating of the oscilloscope. The chassis is all aluminum, with removable vinyl-clad covers. A series of plug«in preamplifiers are available as accessories, as well as the Hughes Multitracer, which permits comparison of a selected number of consecutive sweeps simultaneously.