7000 series readout system

work in progress

For the 7000-series scopes, Barrie Gilbert designed a readout system that allows plugins to display alphanumerical annotations on the CRT screen.

The oscilloscope readout system produces a pulse train consisting of 10 negative-going pulses called time slots.

Each pulse represents a possible character in a readout word, and is assigned a time-slot number corresponding to its position in the word. Each time-slot pulse is directed to 1 of 10 lines, labeled TS-1 through TS-10 (time slots 1 through 10), which are connected to the vertical and horizontal plug-in compartments.

Two output lines, row and column, are connected from each channel (two channels per plug-in compartment) back to the oscilloscope readout system.

Data is encoded on the output lines either by connecting resistors between the output lines and the time-slot input lines, or by generating equivalent currents.The resultant output is a sequence of analog current levels on the row and column output lines.The row and column current levels address a character matrix during each time-slot, thus selecting a character to be displayed or a special instruction to be followed.