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Texas Instruments TI-3510
The
rare TI-3510 appeared shortly after the formal introduction of the TI-2500,
TI-3000 and TI-3500 in
September, 1973. At a first glance it combines the wooden keyboard foil known
from the Exactra 31 with a metal frame for the
ON/OFF switch. Exploring this switch reveals a surprise: The TI-3510 is
always powered:
T-Position
Reads the time in hours and minutes.
C-Position
Normal calculator function known from the TI-3500.
Dismantling
the TI-3510 gives the answer to the "How was it possible" question. A
simple clock chip manufactured by competitor National Semiconductor is wired in
parallel to the calculator chip. The former ON/OFF switch simply selects which
of the two Integrated Circuits is connected to the power.
Today it is difficult to understand why Texas Instruments used a clock chip from a 3rd party manufacturer, the later TI-70 and TI-71 alarm clocks used an own design.
The
above pictures of the Panaplex display demonstrated clearly the main problem of
the TI-3510: Within some years of use the segments of the four digits used by
the clock faded out. We assume that a lot of TI-3510 were trashed and together
with a low production volume - this one is 0003272S manufactured late in 1974 -
it is very rare today.
The TI-3510 was introduced few month after the Corvus 305, a combination of a 10-digit calculator with clock and date function. But these competing twins were not the winner in the calculator-clock combo race, don't underestimate the rare Garrett 2002.
It took another 15 years till Texas Instruments introduced
their second commercial desktop calculator with a built-in clock, don't miss the
unique TI-5315.
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, September 28, 2002. No reprints without written permission.
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