DATAMATH CALCULATOR MUSEUM |
Texas Instruments TI-620
Date of introduction: | 1974 | Display technology: | n.a. |
New price: | $ 299.95 | Display size: | |
Size: | 14.0" x 10.0" x 3.7" | Printer technology: | Drum impact red/black |
Weight: | 6 pounds 8 ounces | Serial No: | 620-067224L |
Batteries: | Date of manufacture: | wk 10 year 1975 | |
AC-Adapter: | 120V AC | Origin of manufacture: | USA |
Precision: | 12 | Integrated circuits: | TMS0203, TMS0221, TMC0306, TMC0406 |
Memories: | 1 + 1 | ||
Program steps: | Courtesy of: | Larry Corrado |
This rare TI-620 was introduced in the year 1974 and seems to be a sibling of the TI-450 and TI-500.
At first glance the TI-620 looks like a modern printing desktop calculator - but it misses the display. On top of the huge keyboard there are only four Status Indicator LED's:
• PW: Power On • M: Memory • OF: OverFlow • K: Constant |
Dismantling
this TI-620 manufactured in March 1975 (Thanks, Larry!) is not an easy task but
from great interest. The
whole calculator is centered around the huge, self-contained printing assembly.
It was manufactured by Japanese Suwa Seikosha Co, LTD.,
better known under the EPSON brand. It has a red/black ribbon and dimensions
are 4.3" x 2.8" x 5.2". There are 15 print columns occupied, but it appears that only 13 of those are for digits and
separators; the right two columns are for op codes.
The
TI-620 uses a calculator architecture based on the
TMS0200 Chipset
for 12-digit desktop calculators but misses the usual 12-digit display. Related calculators using this chip set
are the SR-20 and SR-22. The
first usage of the chip set were the TI-4000 and the Canon 121F.
The
TI-620 is as of today the only calculator known using all four members of the
First Generation TMS0200
Building Blocks:
•
TMS0200 Data Chip – Register Processor with four 16-digit Registers and seven Keyboard Scan inputs • TMS0300 ROM Chip – 512*13 Bits Instruction Memory with serial interface to Data Chip and 13-digit display and keyboard scanning, up to 4 ROM Chips • TMC0400 ROM/Register Chip - 512*13 Bits Instruction Memory with parallel interface to ROM Chip and two 16-digit Registers • TMS0220 Printer Chip – Interface to two-color Drum Printer Mechanism |
If you search in Texas Instruments' own "History Section" for their
first printing calculator, you'll find the TI-5050
introduced one year after this TI-620. The TI-5040
featured the first combination of a display and a printer in a desktop housing.
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, March 26, 2002. No reprints without written permission.