7934

The 7934 is a 500MHz storage mainframe with four bays for plug-ins--two vertical (left) and two horizontal (right). Performance and function is largely determined by the installed 7000-series plug-ins. Plug-ins have a wide variety of functions, including: current and voltage amplifiers, time-bases, spectrum analyzers, sampling amplifiers and time-bases, logic analyzers, as well as a variety of miscellaneous plug-ins. The plug-in modules each use 1, 2 or 3 bays. Storage is provided by variable persistence and bi-stable modes.

Amplifiers are normally installed in the two vertical bays to provide vertical beam deflection, and time-bases in the two horizontal bays to provide horizontal beam deflection. Amplifiers may be installed in horizontal slots for X-Y operation, and time-bases in vertical slots to provide a raster display. Two-bay modules are typically installed in the middle two bays, which enables them to provide both vertical and horizontal deflection of the beam, while three-bay modules are typically installed in the three left-most bays (two vertical and one horizontal slot) to maintain compatibility with three-bay mainframes.

The 7934 makes extensive use of custom integrated circuits and hybrid circuits. With the exception of the on-screen readout circuit, the signal path is completely differential and all of the internal wiring is 50-ohm coax.

Many orthogonal modes of operation are available on the 7934, which control the vertical mode, horizontal mode, storage mode, and triggering:

Storage has normal, bi-stable (standard and "fast"), variable-persistence (standard and "fast") modes, as well as independently-switchable reduced-scan mode (to aid high-speed writing) and timed auto-erase.

The mainframe has the usual analog ch1/ch2/alt/chop/add vertical-mode functions for the two vertical bays, though in the case of the 7934, the two channels are replaced by "left" and "right" to indicate that each mode will slave the vertical deflection to that vertical bay rather than a specific channel. Multichannel plug-ins have internal switching, synchronized by a signal from the mainframe

to both vertical bays, which allows the same vertical-mode functions within each vertical bay plug-in (this is what enables the 7934 to show up to four channels).

Both horizontal compartments are triggerable from either vertical compartment, through an internal signal path. Amplifier plug-ins with two channels provide a switch to select which channel will be given to the mainframe for routing to the triggers. The horizontal modes (A/B/alt/chop) allow the horizontal deflection to be controlled by either the A or B compartment only, or by both, on a time-sharing basis. The mainframe also provides hold-off signals between the two horizontal, which allows a delaying time-base in the A compartment to trigger a delayed time-base in the B compartment. Both the delaying and delayed timebases can be displayed on the screen at once by selecting the chop horizontal mode.