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* [[Media:Tektronix 7854 Test Point and Adjustment Locations D.pdf | 7854 Test Points and Adjustment Locations]] | * [[Media:Tektronix 7854 Test Point and Adjustment Locations D.pdf | 7854 Test Points and Adjustment Locations]] | ||
* [[Media:Tektronix 7854 Schematics D.pdf | 7854 Schematics]] (cleaned up) | * [[Media:Tektronix 7854 Schematics D.pdf | 7854 Schematics]] (cleaned up) | ||
'''Modifications''' | '''Modifications''' | ||
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{{EndSpecs}} | {{EndSpecs}} | ||
== | ==Application Notes== | ||
{{Documents|Link=7854|Class=Application Note}} | |||
* [[:File:Tek 7854-AN-SPSBasic.pdf | Talking to the 7854 scope with TEK SPS BASIC]] (''[[Handshake]]'', Winter 1980/81) | |||
==Prices== | ==Prices== | ||
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* [https://vintagetek.org/7854-mostek-mkb36000-rom-repairs Mostek ROM Repairs @ vintagetek.org] | * [https://vintagetek.org/7854-mostek-mkb36000-rom-repairs Mostek ROM Repairs @ vintagetek.org] | ||
* [https://paulcarbone.com/blog/tektronix-7854/ overview of ROM repair options @ paulcarbone.com] | * [https://paulcarbone.com/blog/tektronix-7854/ overview of ROM repair options @ paulcarbone.com] | ||
==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 sample/hold circuits based on Schottky diode bridges, 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 (direct memory access, i.e. bypassing the CPU). | |||
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, see the [[7854/Repairs|Repairs]] page. | |||
==Pictures== | ==Pictures== |