7854: Difference between revisions

Revision as of 07:46, 9 August 2021

Tektronix 7854

400 MHz waveform-processing scope

Produced from 1980 to 1990

Manuals

Application Notes

Other Info

(All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

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.

Key Specifications

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
Features	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

Internals

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.

Software

Prices

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)

Links

Tek 7854 Design Team
Tek 7854 @ curiousmarc (with links to videos)
Tek 7854 @ amplifier.cd
Tek 7854 @ barrytech.com
Mostek ROM Repairs @ vintagetek.org
overview of ROM repair options @ paulcarbone.com

Pictures

Tektronix 7854 with Waveform Calculator keyboard, 7A26, 7M13, 7D15, 7B87
7854 Front with 7A26,7B85,7B87
7854 Rear, older version
7854 Rear, older version, separate RAM and ROM boards, external battery backup, old-style, silent fan
7854 Rear, newer version, combined RAM and ROM boards, internal battery backup, new-style, less silent fan
7854 Top
7854 Left
7854 Right
Waveform Calculator Keyboard
Waveform Calculator Keyboard
inside the Waveform Calculator Keyboard
Digital section in the 7854
A2 Mode Switch
A2 Mode Switch
The A7 / Auxiliary regulator
A different revision of the A7 board
A11 Main Interface
A15 Signal Output
A15 Signal Output
A15 Signal Out Board
A17 Horizontal Amp Board
A18 Vertical Amp Board
A19 Vertical Channel Switch
A19 Vertical Channel Switch
A20 High Voltage
A21 Z-Axis
A25 Digitizer
A26 Control Logic Board
A26 Control Logic Board
A26 Control Logic Board
A27 MPU
A different revision of the A27 board
A28 RAM Board
A28 RAM Board with option 2D (RAM Expansion)
A29 Display Board
A30 / GPIB board
A30 GPIB, different revision
A31 ROM Board
A32 Rear Panel Connector
Picture of 7854 during development. Note the different measurement keyboard layout. Picture might date from late 1978
Picture of designing the 7854 waveform calculator keyboard. note the different Keyboard layout.
Alignment Pattern
Program for generating Alignment Pattern
Mainframe rise time measured with 067-0587-02

Memory Maps

Devices with separated ROM and RAM boards (SN < B100000)

Address Range	Size	ICs	Purpose
0000...3FFE	8k	U100+U110	ROM
4000...7FFE	8k	U200+U210	ROM
8000...8FFE	2k	U300+U310	PATCH ROM “for future use”
9000...9FFE	2k	U400+U410	PATCH + ROM
			2k RAM	4k RAM	8k RAM
A000...A7FE	1k	U510+U520+U530+U540	x	x	x
A800...AFFE	1k	U610+U620+U630+U640		x	x
B000...B7FE	1k	U710+U720+U730+U740			x
B800...BFFE	1k	U810+U820+U830+U840			x
C000...C7FE	1k	U110+U120+U130+U140			x
C800...CFFE	1k	U210+U220+U230+U240			x
D000...D7FE	1k	U310+U320+U330+U340		x	x
D800...DFFE	1k	U410+U420+U430+U440	x	x	x
E000...E37E			GPIB, Keyboards, Digitizer,...
E380...FFFE			Reserved for Diagnostic Interface

Devices with combined RAM+ROM Board (SN >= B100000)

Address Range	Size	ICs	Purpose
0000...7FFE	16k	U220+U320	ROM
8000...9FFE	4k	U200+U300	ROM for future use
A000...DFFE	8k	U400+U410	RAM
E000...E37E	4k		GPIB, Keyboards, Digitizer,...
E380...FFFE			Reserved for Diagnostio Interface

Devices with installed Diagnostic Boards (all serial numbers)

Address Range	Size	ICs	Purpose
0000...0FFE	2k	U430+U330	ROM
1000...1FFE	2k	U410+U310	ROM
2000...2FFE	2k	U200+U100	ROM
3000...3FFE	2k	U220+U120	ROM
4000...4FFE	2k	U420+U320	ROM
5000...5FFE	2k	U400+U300	ROM
6000...6FFE	2K	U210+U110	ROM
7000...7FFE	2K		ROM for future use
8000...7FFE	4k		Not used
9800...9FFE			RAM in Microlab I, disabled when standard ROM is in 7854
A000...DFFE	2...8k		RAM – see tables above
E000...E37E			GPIB, Keyboards, Digitizer,...
E380...E39E			BKREGCS Breakpoint address register chip select
E3A0...E3BE			CTREGCS control register chip select
E3C0...E3DE			BKDATA breakpoint data latch
E3E0			F/P Display Data
E3E2			F/P Display Data
E3E4			F/P Keyboard Data
E3E6			F/P Keyboard flag reset
E3E8			Terminal I/O Control
E3EA			Terminal I/O Data
E3EC			Cassette I/O Control
E3EE			Cassette I/O Data
E3F0			Modem I/O Control
E3F2			Modem I/O Data
E3F4...E3FE			ONBDIO on board input/output to microlab I
E400...E7FE			RAM in Microlab I
E800...EFFE		U120+U225	ROM - bank switched by PROMBK
F000...FFFE		U220+U320	ROM - bank switched by PROMBK

@@ Line 1: / Line 1: @@
-{{Oscilloscope Sidebar |manufacturer=Tektronix |designers=|
+{{Oscilloscope Sidebar
-model= 7854|
+|manufacturer=Tektronix
-image=tek7854.jpg|
+|series=7000-series scopes
-caption=Tektronix 7854 on a [[K213]] cart|
+|model=7854
-introduced=1980 |
+|image=tek7854.jpg
-discontinued=1990 |
+|caption=Tektronix 7854 on a [[K213]] cart
-summary=400 MHz waveform-processing scope|
+|introduced=1980
-manuals=
+|discontinued=1990
+|summary=400 MHz waveform-processing scope
+|designers=Tom Rouseau;Les Larson;Jack Collins;Ellen Deleganes;Jim Schlegel;Gary Fladstol;Val Garuts;Tim Holte;Burt Johnson;Bruce Kingsland;Wes Kosta;Jim Tallman;Kirk Wimmer
+|manuals=
 * [http://w140.com/070-2874-01.pdf Tektronix 7854 Manual (PDF, OCR)]
 * [http://w140.com/7854_manual_change_info_d.pdf Tektronix 7854 Manual Change Information (PDF)]
@@ Line 66: / Line 69: @@
 ==Internals==
 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
+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.
-based sample/hold circuits and a single 10-bit successive-approximation ADC.  The Y sample value is then
+The Y sample value is then written into the memory location addressed by the X value, using DMA.
-written into the memory location addressed by the X value, using DMA.
-The CPU in the 7854 is a [https://en.wikipedia.org/wiki/Texas_Instruments_TMS9900 Texas Instruments TMS9900 16-bit microprocessor],
+The CPU in the 7854 is a [https://en.wikipedia.org/wiki/Texas_Instruments_TMS9900 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.
-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, [[7854rom|outlined here]].