The Tektronix 7854 Waveform Processing Oscilloscope, introduced in 1980, is a 400 MHz combined analog / digital mainframe in the 7000 series that takes two vertical and two horizontal 7000-series plug-ins. In addition to a conventional analog (real time) scope, it contains an equivalent-time sampling 10-bit digitizer and a programmable waveform processor with GPIB interface. The project manager for the 7854 was Tom Rousseau.
The waveform processor can be programmed using a detachable calculator-style keyboard, using postfix operators ("reverse Polish notation" like HP calculators) that operate on entire waveforms, not just individual numbers.
|Bandwidth||(analog) 400 MHz|
|Fastest cal. sweep||500 ps|
|Sample rate||500 kHz (stores repetitive waveforms up to 400 MHz)|
|Acquisition depth||128, 256, 512 or 1024 points|
|Memory capacity||2048 waveform points in up to 16 waveforms (optional expansion to 5120 points and 40 waveforms)|
|Single shot||events and pretrigger up to 50 µs/div ("2.5 µs/point") with the 7B87 Time Base|
|CRT||154-0644-05, P-31, or 154-0893-09, P-11|
The acquisition system uses what Tektronix termed a "display-oriented random sampling digitizing technique". It simultaneously digitizes a pair of X and Y signal values at a rate of 3.5 µs/point, using Schottky diode bridge based sample/hold circuits and a single 10-bit successive-approximation ADC. The Y sample value is then written into the memory location addressed by the X value, using DMA.
The CPU in the 7854 is a Texas Instruments TMS9900 16-bit microprocessor, known from the infamous TI-99/4 home computer of the late 70s, with 32+6KByte ROM and 8KByte RAM.