DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
Texas Instruments TI-58C (1979)
| Date of introduction: | 1979 | Display technology: | LED-stick |
| New price: | $90 (October 1981) |
Display size: | 10 (8 + 2) |
| Size: | 6.4" x 3.2" x
1.5" 162 x 81 x 37 mm3 |
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| Weight: | 8.5 ounces, 240 grams | Serial No: | 7183855 |
| Batteries: | BP1A | Date of manufacture: | wk 17 year 1979 |
| AC-Adapter: | AC9131 | Origin of manufacture: | USA (ATA) |
| Precision: | 13 | Integrated circuits: | TMC0501E,
TMC0580 (CD2400),
TMC0580 (CD2401),
TMC0573, TMC0591, RCA 10341XX TMC0541 |
| Logic: | AOS - 8 Pending Operations, 9 () | ||
| Memories: | 0-60 | ||
| Program steps: | 480-0 | Courtesy of: | Mark Bollman |
| Download leaflet: | 
(US: 2.0M Bytes) |
Download manual: |
The
main disadvantage of the TI-58, its non-permanent
program storage, was corrected with the TI-58C. Replacing the two
TMC0598 Multi-Register Chips of the TI-58
manufactured in a power-hungry PMOS process with a low-power CMOS RAM (Random
Access Memory) chip, battery drainage caused by the NiCd batteries itself was
quicker than drop caused by powering the RAM.
Dismantling
the featured TI Programmable 58C calculator manufactured already in April 1979
by Texas Instruments in Abilene, TX reveals a very early design with a printed
circuit board (PCB) manufactured in Canada and sporting some patch wires to fix
a design problem, also known as blue wires.
Digging deeper
into the circuitry of this early TI-58C tells an interesting story: Instead of porting the TMC0598 Multi-Register Chips designed in power-hungry PMOS technology used with the TI-58 into modern CMOS technology, the engineering team decided to use a standard SRAM (Static Random Access Memory) manufactured in a power-saving CMOS process and developed with the TMC0590 Continuous Memory Interface Chip a
TMS0500 Building Block to translate the signals of the TMC0501E Arithmetic Chip to the common signals of SRAMs with a capacity of 1k*4 Bits.
The featured TI-58C manufactured in April 1979 uses the following main Integrated
Circuits (ICs):
TMC0501E Enhanced Arithmetic Chip: Register Processor with five 16-digit Registers and segment decoder/driver.
TMC0580 (CD2400/CD2401) Double Scanning and Read Only Memory Chips: 2.5k*13 Bits Instruction Memory with serial interface to Arithmetic Chip, 16 Constants with 16 digits, each and 16-digit display scanning.
Two chips stacked in a piggy-back manner on top of each other.
TMC0560 (TMC0573) Bare Read Only Memory Chip: 1k*13 Bits Instruction Memory with serial interface to Arithmetic Chip
in a small 8-pin package.
TMC0590 (TMC0591) Continuous Memory Interface Chip: Adopts 1k*4 Bits CMOS SRAM with backup battery to Arithmetic Chip.
RCA 10341xx CMOS RAM: 1k*4 Bits CMOS SRAM with Texas Instruments internal part number, most likely a MW5114 chip.
This first version of the TI Programmable 58C using a CMOS RAM chip manufactured by RCA was
soon replaced with the second version of the TI-58C
based on a Toshiba or NEC chip.
Read more about your first steps of programming this calculator here.
If you are interested in the calculating accuracy of scientific calculators don't miss the Calculator forensics.
Comparing
the Constant ROM Content with
the programmed constants frequently used with computing algorithm of
trigonometric functions like sine, cosine, or tangent of an SR-50 manufactured in
May 1974 still using the original TMC0521-2 SCOM Chip with the TMC0580 (CD2400)
DSCOM Chip
of the featured TI-58C with our
TMS0500 Platform after recording their
ROM Images showed no
differences.
Looking into the Key Codes programmed into the second half of the
TMC0580 (CD2400) and the complete TMC0580 (CD2401) and comparing with its
TMC0582 and TMC0583 counterparts known from the TI-58 and TI-59 shows unexpected
differences that we need to analyze. Comparing the
Instruction ROM Content
distributed over the two TMC0580 SCOM and one TMC0560 BROM Chips of the
featured TI-58C with a TI-59 manufactured in May 1979 showed as expected many differences.
The TI-58C continued the usage of the Solid
State Software Modules� with up to 5000 program steps introduced with the
TI-58 and TI-59 already in 1977. On the backside of the
TI-58/59 you'll note a small lid with a place for a module. The Master Library
with 25 different programs was included, a lot of other modules were available.
We know four different approaches of the module expansion:
| � Standard modules like the Master Library use only the small
sticker above the A,B,C,D, and E keys. � Other modules like the Pool Water Analysis developed by Olin Corporation make use of a colorful keyboard mask. � Customized calculators like the USMC AV-8C calculator or insurance calculators sold by Allianz and others use special keyboard arrangements. | � The CAL-Q-TAX and incotax calculators use an extender instead the usual drop-in modules. |
The TI-58C carries the connector to the printing cradle. It seems to work on the PC-100C revision.
American Micro Products introduced with the Module Selector a very interesting product fitting into the charging bay of the printing cradles.
The calculator was available till 1983 before it was discontinued and replaced with the TI-66 Programmable. Don't miss the rare and innovative Franken-Calculator Data Dimensioner.
Andreas Gerlich scanned recently the German documentation of the TI-59, please
visit his website. Thanks!
Fellow calculator collector Marek Czeszek prepared wonderful Step-by Step Instructions how to clean a TI-58C.
| TI Programmable 58C
Advanced programmable calculator with plug in Solid State Software* and Constant Memory*. Features TI�s exclusive Solid State Software*, tiny, pre-programmed modules you slide into the calculator to extend power, flexibility, and range. It is also keyboard-programmable. Constant Memory* feature retains data and program information even when off. � Texas Instruments, 1981 |
If you have additions to the above article please email: joerg@datamath.org.
� Joerg Woerner, February 27, 2021. No reprints without written permission.