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7854: Difference between revisions
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{{Oscilloscope Sidebar |manufacturer=Tektronix | | {{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/070-2874-01.pdf Tektronix 7854 Manual (PDF, OCR)] | ||
* [http://w140.com/7854_manual_change_info_d.pdf Tektronix 7854 Manual Change Information (PDF)] | * [http://w140.com/7854_manual_change_info_d.pdf Tektronix 7854 Manual Change Information (PDF)] | ||
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==Internals== | ==Internals== | ||
The acquisition system uses what Tektronix termed a "display-oriented random sampling digitizing technique". | 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]]. | 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]]. | ||