TI Programmer

TI-Programmer
TI-Programmer

A pocket calculator, which is pretty unusual for normal peoples' usage, is the model "Programmer" from Texas Instruments: This calculator, which appeared on the market in 1977 and which was produced several years, is only capable of the four standard calculations, but is also able to calculate in the hexadecimal and octal number system. And with a few hints, you can also work with binary numbers.

Those calculators were't suitable for normal households, but were mainly used by software developers and computer programmers, which had to calculate bit by bit because of the power-less computers with very tiny memories that time.

As interesting as the TI Programmer is by its special calculations, as boring is it in its technical construction. More about that later.


case lock in battery compartment
case lock in battery compartment

Case and Keyboard

The plastic case of the TI Programmer consists of two case parts, which are tied together only by a few stong plastic barbs. No screw, nothing expensive at all. Simple, but efficient.

The upper case half has got a red inlay on its upper third. This inlay is partially tilted and covers the LED display. Beyond the display, there's the embossed "Texas Instruments" logo. The whole inlay is surrounded by a silver colored frame.
The rest of the calculator is used from the keyboard and its aluminium cover plate. This brown plate is printed in white and blue.

The keyboard is simple constructed: There are fourty(!) keys, internally covered by a foam (which does not last that line), which press on the key plates and give an acustically and haptically feedback. The keys hardly bounce, but for some reasons, they are pretty slow to use.


keyboard: contact keys
keyboard: contact keys

This calculator does not have an On/Off switch, but is instead activated and switched off by two keys. This way, TI could save a real switch, which needed a stronger case and was prone to misfunctioning.


keyboard: inner key side
keyboard: inner key side



Construction

Inside view
Inside view

The inner construction of the calcualtor was quite revolutionary for 1977, but on the same time very boring, too. Except the keyboard and the mainboard, which only contains one chip and the LED stick, there are no further parts used. No resistors, no capacitors, no transformers, no forther ICs.

TI really perfectionized the "Calculator On A Chip".

Display

LED display
LED display

The very bright LED display with its strong magnifying bubbles was up-to-date that time.
Due to the small size of the light emitting fields (they had to keep the power consumption as low as possible), the tiny digits had to be enlarged massively by strong bubbles. The disadvantages of that technics were, that the display seems to lay deep down in the case and even worse, it is not possible to look at it sideways or at an tilting angle.

The display is driven as usual in a multiplexing way, but here, the multiplexing frequency seems to be quite suboptimal since the display flickers noticeably.

To save even more power, after 30 seconds without use interaction, the display is switched off and only a moving dot reminds the user, that the calculator is still powered on. The last value can be brought back into the display by pressing the "=" key.


moving dot in powersave mode
moving dot in powersave mode

After about five minutes without any entries, the calculator switches off automatically.

CPU

mainboard with CPU and LED display
mainboard with CPU and LED display

The TI-Programmer uses the "Calculator On A Chip" ZA0675NL CPU. In the calculator described here, this chip was made in week 19, 1979 in Singapore.

The construction of that calculator is identical to the TI-30; they only differ by the used CPU (which probably only differs by the firmware).

Calculating Capabilities

The normal calculating capabilities of the TI Programmer are not very spectacular: In the normal mode, it can only do the four standard calculations, up to four brackets and has got a simple memory with a summary function.


hexadecimal mode
hexadecimal mode

In the hexadecimal- and octal more, there are a number of further calculating operations such as the 1 complement, AND, OR, XOR and bitwise shifting. The hexadecimal mode is indicated by a double apostrophe; the octal mode by a simple apostrophe.


octal mode
octal mode

The calculation range goes up to 99999999, ocal to 37777777 (8388607 decimal = 2^23-1) and hexadecimal to 7FFFFFFF (134217727 decimal = 2^27-1).

Overflow and division are indicated by a display full of "E"s:


error indication
error indication

The memory function is realized by three keys; there's no display indicator: "STO" stores the displayed number, with "RCL", the memory store can be recalled into display, and with "SUM", the current displayed number is added to the memory contents.

Specialities




Batterypack BP-8
Batterypack BP-8

As most calculators of Texas Instruments, the TI-Programmer also contains a so-called "Batterypack", here of the type BP-8, which consists of two rechargable AA cells, who generate the neccessiary voltage of 9V DC. The AA cells are recharged by an external transformer, which delivers 8.5V AC. During the recharge, the calculator can be used, of course.

Unfortunately, the integrated accus leak after a while, since the calculator uses a little bit of electricity, even when it is switched off.

Such a leaked AA cell pair can be replaced by an expert.


inside the batterypack
inside the batterypack

Some data regarding the power consumption:
The consumption of the calculators on its 9V connector is 16µA (=0.15mW), when switched off, is 12mA (=0.1W) when only one zero is shown, is 44mA (=0.4W), when all digits are on and on the power-saving mode, it still consumes 7.3mA (=0.065W).

The 0.4W were undercutted by calculators with VFD display, and those displays were also larger and readable from all positions. But the drawback of them were, that they needed a number of external parts, which were not possible on a "Calculator On A Chip" design.

Summary

The TI-Programmer is a technical rather boring, but due to its unusual functions rare and interesting pocket calculator. Such a model is an enrichment of a collection.

Technical data

ManufacturerTexas Instruments (TI)
ModelProgrammer
Year1980
CPUZA0675NL
Display8+1 digit LED
Number of keys 40
Functions+ - * / M HEX OCT AND OR XOR SHIFT 1C ( )
Entry logic (classificationALG (BGAA)
1 + 0.000 = 1.
0 / 0 = Error
Power supply 2xAA (internal)
Size14,7 x 7,7 x 3,4cm
Serial Number0380RCI
Original PriceDM 198,00
ConditionA-
Factsheet


Links
Datamath Calculator Museum: TI Programmer (en) (The first place for TI calculators)