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Texas Instruments TI-5230

Date of introduction:  1977 Display technology:  Fluorescent
New price:   Display size:  12
Size:  12.0" x 12.3" x 3.3" Printer technology:  Thermal TP-20225, TP-27225
Weight:  6 pounds 2 ounces Serial No:  
Batteries:   Date of manufacture:  
AC-Adapter:  120 V or 220 V Origin of manufacture:  USA
Precision:  12 Integrated circuits:  TMC0501E, TMC0572, TMC0587, TMC0588, 7*TMC0598, TMC0255, TMC1376
Memories:      
Program steps:  200 Courtesy of:  Joerg Woerner

This rare TI-5230 seems to be an enhanced version of the TI-5225. We notice 16 added keys compared with the basic calculator but [START], [STOP] and [ENTER] are not common labels for a simple desktop calculator.

We decided to dismantle the TI-5230 to reveal its true genes and found a real surprise under the cover of the huge housing. Please watch the following 4 pictures carefully.

The internal construction of the TI-5230 is a typical design of Texas Instruments. We know the style from the TI-5225 but notice two stacked printed circuit boards (PCB's).

TI-5230_1.jpg (159896 Byte)

The lower PCB makes use of two single-chip calculator chips to control both the thermal printer and the display. TI-5230_2.jpg (143895 Byte)
The upper PCB mixes some 28-pin devices with 10 smaller devices. A known relationship... TI-5230_PCB.jpg (155156 Byte)
Looking closer on the upper PCB gives with the TMC0501E Arithmetic Chip and lots of memory a real surprise!  TI-5230_IC.jpg (116448 Byte)


With the TMC0500 Building Blocks for Scientific and Programmable Calculators Texas Instruments created a novel architecture for scalable scientific calculators. The architecture used in a minimum configuration as used with the SR-50 a 2 chip design with the TMC0501 Arithmetic Chip and the TMC0520 SCOM (Scanning Read Only Memory) Chip, but was expandable to a maximum of 8 SCOMs, additional RAM as program memory for programmable calculators, additional RAM for general purpose registers and even a chip driving a printer. Most scientific and programmable calculators from Texas Instruments manufactured between the years 1974 and 1982 rely on these chips. Please find all known calculators using the TMC0500 architecture here.

Combining all numbers found on the integrated circuits of the TI-5230 adds to an impressive Bill-of-Material:

Part Number Amount Description
TMC0501E 1 Arithmetic Chip with up to 13 digits precision based on
Chipset for scientific calculators
TMC0572 1 Bare Read Only Memory (BROM) with 1k*13 Bits instruction memory
TMC0587 1 Double Scanning and Read Only Memory (DSCOM) with 2.5k*13 Bits instruction memory and 16*16 digits constants
TMC0588 1 Double Scanning and Read Only Memory (DSCOM) with 2.5k*13 Bits  instruction memory and 16*16 digits constants
TMC0598 7 External Random Access Memory for user programs with 240*8 Bits of read/write memory (240 program steps or 30 data registers) each
TMC0255 1 Driver for thermal printer
TMC1376 1 Driver for display based on Third generation single chip calculators

Overall the complexity is centered between the well known TI-59 and the flagship SR-60A!

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If you have additions to the above article please email: joerg@datamath.org.

Joerg Woerner, June 11, 2005. No reprints without written permission.