7704

The Tektronix 7704 is a four-bay mainframe introduced in 1969 that takes two 7000-series vertical plug-ins and two 7000-series horizontal plug-ins. The rated bandwidth is 150MHz for the 7704 and 200MHz for the 7704A. There was also an option (option 9) to have the bandwidth extended to 250MHz.

The 7704 has a special modular construction. At the bottom is the "acquisition unit", which contains the power supply, plug-in slots, and main interface board. On top is the "display unit", which contains the CRT, HV power supply, and output amplifiers for driving the deflection plates of the CRT. These units detach. A large multipin connector passes signals and power from the acquisition unit to the display unit. It is important not to damage this connector when assembling or disassembling the units.

An optional component, the P7001 Processing Unit, can be added to a 7704A between the acquisition unit and the display unit. The P7001 has a backplane with an asynchronous bus and several cards that plug into that bus: sampler, analog to digital converter, memory, and display electronics. Early versions of the P7001 use core memory. Later versions use semiconductor RAM. The P7001 assumes a repeating input signal and periodically samples the horizontal and vertical signals simultaneously. This allows it to fill the memory with data points represented as coordinate pairs, (x1,y1), (x2,y2), (x3,y3), etc. It is not necessary that x2 be greater than x1. The samples can be taken out-of-order with respect to their equivalent time in the waveform. The signal coming from the acquisition unit enters a fast four-diode sample and hold circuit where it is sampled at 150Ksamp/sec. Each sample is digitized using a successive-approximation scheme. The analog to digital converter is made of several chips: a digital to analog converter, a comparator, and control logic. The P7001 has its own power supply built into it, independent from the power supply in the acquisition unit of the 7704A. The bus is used for low speed signals. High speed signals are sent through coaxial cables that connect to the cards using Peltola connectors.

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  Left side of 7704 contains power supply.

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  Right side of 7704 contains readout circuitry.