DATAMATH CALCULATOR MUSEUM
Texas Instruments TI-1800
|Date of introduction:||1997||Display technology:||LCD|
|New price:||Display size:||10|
|Size:|| 5.8" x 4.3" x 0.95"
148 x 110 x 24 mm3
|Weight:||4.0 ounces, 112 grams||Serial No:|
|Batteries:||1*LR54 (30µA)||Date of manufacture:||mth 05 year 1997|
|AC-Adapter:||Origin of manufacture:||China (N)|
|Program steps:||Courtesy of:||Joerg Woerner|
This TI-1800 is a very useful calculator for Tax calculations combining both a large and bright display and a valuable appearance. Compare to the more basic TI-1795+.
Dismantling this TI-1800 manufactured in May 1997 by Nam Tai Electronics in China reveals a clever design centered around an unknown single-chip calculator circuit mounted in Chip-on-Board (COB) technology on a small double-sided printed circuit board (PCB) and powered by four solar cells and a small LR54 (LR1130) backup battery. With calculators sporting COB technology you find always two requirements for the PCB to balance:
|• Keyboard: Simple technology and big area
• Calculating electronics and display connection: expensive technology and small area
Engineers at Nam Tai Electronics developed a smart and very
economical solution; A larger, single-sided PCB is used for the keyboard and connected with a short
flat flexible cable (FFC) to the smaller and very complex double sided PCB for
the calculator electronics. Please compare this design with a
TI-1795+ manufactured in 1996 by
Kinpo Electronics and still using a
conventional flat-pack housing and just one PCB.
Inspecting the PCBs of this TI-1800 calculator brought our attention to a small mark reading TI-1800 PD308-3, We spotted a very similar PCB-Mark already with the TI-1795+ and started compiling a list of the PCB-Marks on calculators manufactured by OEMs for Texas Instruments.
If you have additions to the above article please email: firstname.lastname@example.org.
© Joerg Woerner, December 5, 2001. No reprints without written permission.