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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. Single-shot, pretrigger acquisition is possible with the special 7B87 time base using real-time sampling. 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)
Resolution 10 bit
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); cathode −3 kV, anode +21 kV, distributed vertical deflection plates
  • Signal Averaging
  • Cursor measurements
  • Waveform parameter measurements
  • GPIB Interface (Standard)
  • Waveform calculation operators - add, multiply, square root, log, abs
  • Internal RPN programming language (Reverse Polish Notation)
  • Keystroke Programming (Up to 2000 Keystrokes with Option 2D)
  • programmable text display on screen


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.

The firmware consists of mask ROMs, an FPLA, and patch EPROMs. These ROMs (particularly the early ones from Mostek) are a common point-of-failure. Several remedies exist, outlined here.



Year 1981 1990
Catalog price $10,500 $17,000
2019 value $29,360 $33,060

Diagnostic Test Interfaces

Extender Boards

  • 067-0913-00 Extender Board 44-Pin (used with the A30-GPIB and A31-ROM Boards)
  • 067-0914-00 Extender Board 80-Pin (used with the A27-MPU and A28-RAM Boards)
  • 067-0915-00 Extender Board 124-Pin (used with the A26-Control Logic and A29-Display Boards)