Abstract: An oscilloscope to sequentially store, process and display an electrical input signal according to various signal events and characteristics. The oscilloscope is physically and functionally modular having both selectable hardware configurations from among various "plug-in" modules and selectable processing and display features chosen from among a predetermined selection by software control contained, in part, within the plug-in modules. The particular control settings, as well as a representation of the signal itself, is recorded on a removable storage device, such as a magnetic disc. High frequency signals are sampled, digitized and stored in a high speed intercascaded signal memory, independent from the program and data memory associated with the oscilloscope signal processing.

Abstract: A D/A converter for converting a digital signal having a number of bits to an analog signal. The converter is fabricated in an integrated circuit digital array including a register for storing the particular number of bits, a buffer circuit for receiving those bits from the register, and an analog current switching network. The analog current switching network includes a number of current switching circuits, each of which provides the proper current output in response to the delivery of an associated bit from the buffer circuit. Each current switching circuit includes an emitter coupled switch circuit having two pluralities of parallel connected transistor cells with the bases of one of the plurality of transistor cells connected with the buffer circuit and the bases of the other of the plurality of transistor cells connected with the current switching circuit.