7000 series readout system: Difference between revisions
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==Analog-ROM Readout Board== | ==Implementation== | ||
===Analog-ROM Readout Board=== | |||
===Character generation=== | ====Character generation==== | ||
[[File:7000-readout-chargen-positions.jpg|thumb|300px|right|Character generator matrix positions in 7000 series readout analog character generator ROM]] | [[File:7000-readout-chargen-positions.jpg|thumb|300px|right|Character generator matrix positions in 7000 series readout analog character generator ROM]] | ||
The character generators are custom analog chips that provide X and Y output currents for ten characters of up to seven strokes (eight X/Y coordinate pairs) inscribing each character. The in-character coordinate points are selected through a triangular analog signal, not a digital code, which in turn activates one of eight groups of three transistors each generating the X/Y output currents. Each of these groups is fed a constant emitter current (I<sub>E</sub>), and the distribution of this current to the three transistors is controlled by their different emitter areas. The first and second collectors provide X and Y currents respectively, the third ("Z") directs current to the substrate (I<sub>E</sub> - I<sub>X</sub> - I<sub>Y</sub> - I<sub>Z</sub> = 0). Actually, the emitter area itself is not varied in the mask, but out of a fixed number of emitters of equal size, a certain number is connected on each transistor: [[File:7000-readout-chargen-circuit-1.jpg|300px|thumb|ROM circuit for one character (digit "3"). Bases are scanned in turn. The numbers under the emitters indicate how many of the emitters are connected to the common rail. Ten such character circuits plus the scanning (base drive) circuit are integrated in each ROM chip. All X and Y collector outputs are connected across characters and chips.]] | The character generators are custom analog chips that provide X and Y output currents for ten characters of up to seven strokes (eight X/Y coordinate pairs) inscribing each character. The in-character coordinate points are selected through a triangular analog signal, not a digital code, which in turn activates one of eight groups of three transistors each generating the X/Y output currents. Each of these groups is fed a constant emitter current (I<sub>E</sub>), and the distribution of this current to the three transistors is controlled by their different emitter areas. The first and second collectors provide X and Y currents respectively, the third ("Z") directs current to the substrate (I<sub>E</sub> - I<sub>X</sub> - I<sub>Y</sub> - I<sub>Z</sub> = 0). Actually, the emitter area itself is not varied in the mask, but out of a fixed number of emitters of equal size, a certain number is connected on each transistor: [[File:7000-readout-chargen-circuit-1.jpg|300px|thumb|ROM circuit for one character (digit "3"). Bases are scanned in turn. The numbers under the emitters indicate how many of the emitters are connected to the common rail. Ten such character circuits plus the scanning (base drive) circuit are integrated in each ROM chip. All X and Y collector outputs are connected across characters and chips.]] | ||
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[[File:Tek-7000-readout-board.jpg|400px|center|Analog-ROM readout board (from [[7904]] built in 1981)]] | [[File:Tek-7000-readout-board.jpg|400px|center|Analog-ROM readout board (from [[7904]] built in 1981)]] | ||
===Custom chips=== | ====Custom chips==== | ||
* [[155-0014-01]] Analog to Decimal Converter | * [[155-0014-01]] Analog to Decimal Converter | ||
* [[155-0015-01]] Analog Data Switch | * [[155-0015-01]] Analog Data Switch | ||
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* [[155-0038-01]] D/A converter | * [[155-0038-01]] D/A converter | ||
==EPROM-based Readout Board== | ===EPROM-based Readout Board=== | ||
[[File:EPROM based 7000 series readout board.jpg|400px|right]] | [[File:EPROM based 7000 series readout board.jpg|400px|right]] | ||
Towards the end of the 7000 series lifespan, in the 2nd half of the 1980s, a re-designed readout board, | Towards the end of the 7000 series lifespan, in the 2nd half of the 1980s, a re-designed readout board, | ||
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==Microcontroller-based Readout Board== | ===Microcontroller-based Readout Board=== | ||
Finally, from 1989/1990 on, a third generation readout board designed around an 80C31 micro-controller replaced the previous versions in the last series of [[7104]], [[R7103]], [[R7844]] and [[7904A]] models.This version no longer used any Tek-made special ICs, manufacture of which had been discontinued by that time. The 8031 based board is described in [http://w140.com/Tek_7904_OCRed_by_Tabalabs.pdf this version of the 7904A manual]. | Finally, from 1989/1990 on, a third generation readout board designed around an 80C31 micro-controller replaced the previous versions in the last series of [[7104]], [[R7103]], [[R7844]] and [[7904A]] models.This version no longer used any Tek-made special ICs, manufacture of which had been discontinued by that time. The 8031 based board is described in [http://w140.com/Tek_7904_OCRed_by_Tabalabs.pdf this version of the 7904A manual]. | ||
[[File:Microcontroller based readout board block diagram.jpg|600px|Block diagram of 8031 based readout board]] | [[File:Microcontroller based readout board block diagram.jpg|600px|Block diagram of 8031 based readout board]] | ||