INTRODUCTION. 1-2. The Model 104-D MEMO-SCOPE oscilloscope is a storage type oscilloscope. In addition to its capabilities for use as a conventional type oscilloscope, the MEMO-SCOPE oscilloscope has the feature of being able to retain the displayed traces of waveforms, and retaining such traces on the screen for as long as desired (within limits stated in Section II, OPERATING INSTRUCTIONS). Thus, non-periodic waveforms, transients, and spurious signals of a "one-shot" nature can be displayed, and then retained on the screen of the CRT after they have gone. When using this feature, the stored display on the MEMO-SCOPE oscilloscope is much like that of a photograph, holding for later study information which would ordinarily be difficult or impossible to visually observe during its actual occurence. 1-3. MEMOTRON TUBE. To accomplish its storage feature, the MEMO-SCOPE oscilloscope uses a Hughes Products MEMOTRON tube (RETMA 6498). This unusual tube stores the trace of the writing beam (the electron beam), and displays this trace with whatever brightness is required, at a constant intensity. The trace can be stored indefinitely, with appropriate voltages applied through selective positioning of the storage controls on the front panel of the MEMO-SCOPE oscilloscope. The MEMOTRON tube thus acts as a CRT with a controllable persistence: (1) For normal operation as a conventional oscilloscope, a short persistence may be selected (storage control off); (2) For storage operation, proper positioning of the storage controls converts the MEMOTRON tube to a long persistence tube. When using the storage feature, the stored trace can be retained for as long as desired, and then erased by simply depressing the ERASE button on the front panel of the MEMO-SCOPE oscilloscope (see figure 1), or by grounding the external ERASE jack. 1-4. THE STORAGE MECHANISM. The MEMOTRON tube has a dielectric storage mesh and two electron guns: (1) Writing Gun; (2) Flood Gun. The flood gun (figure 2) sprays the dielectric storage surface with a uniform barrage of low-velocity electrons. The dielectric surface is assumed to be initially at zero potential (flood gun cathode potential). The high-velocity electron beam from the writing gun charges regions of the storage surface positive as a result of secondary emission, thus creating areas which are partially transparent to the flood electrons. Those which pass through the positively charged areas are accelerated to high velocity, and strike the viewing screen phosphor, producing a continuously visible image of the pattern electrically stored on the dielectric surface. In addition to providing the electrons necessary for displaying the written information, the flood gun beam also maintains the positive and negative potentials of the charged pattern on the storage surface. This pattern may be erased by momentarily lowering the voltage on the secondary collector mesh inserted between the writing gun and the dielectric surface. A given area on the storage mesh may be at one of two stable conditions, either at collector or at flood gun cathode potential. All written information will be displayed at full brilliance with no presentation of half-tone information. 1-5. Operation Without Storage: The MEMO-SCOPE oscilloscope can be used with the storage controls turned counterclockwise and FLOOD GUN turned OFF, causing it to operate exactly like a conventional oscilloscope. This mode of operation (in addition to its obvious use) is very useful in preliminary adjustments to establish the proper sweep and amplitude adjustments for later observation of transient phenomena in the storage mode. 1-6. Beam Intensity: As in any convention&l oscilloscope, the writing gun intensity must be increased when faster writing speeds are used. Insufficient beam intensity will result in partial storage of the trace. Similarly, too high an intensity for the writing speed being used will cause "blooming" of the trace, and fogging of the background, especially at very low writing speeds.