DATAMATH CALCULATOR MUSEUM
With the TMS0800 Texas Instruments introduced in the year 1974 one of the three successors of the TMS0100 single-chip calculator design. In opposite to the TMS0100 with the discrete segment- and digit-drivers the TMS0800 needs only external digit-drivers to drive the seven-segment LED display. The chip contains 3,520 Bit Read-Only program memory (320 Words x 11 Bits), a 154-bit Serial-Access Memory (SAM, 3 Registers * 11 Digits, 2 * 11 Bit-Flags) and a decimal arithmetic logic unit as well as control, timing, and output decoders with segment drivers for the display. These function blocks of the chip add up to an overall complexity of roughly 5,000 transistors.
Due to a flexible design concept with a programmable ROM some design variations appeared.
A typical calculator built around the TMS0800 family performs the four basic functions +, −, ×, and ÷ and adds the %-function.
|TMS0801||Sinclair Cambridge||sign + 8||Constant|
|TMS0803||TI-1500, TI-2500-II, Exactra 21, Exactra 22, Exactra 23, Montgomery Ward P100, Western Auto M4993||sign + 8||%|
|TMS0805||Sinclair Scientific||sign + 8||UPN|
|TMS0807||Canon LE-85||sign + 8||sqr(x), %|
|Int. CK||100||160||200||kHz||Rint= 100k Ohm|
The TMS0800 was manufactured in a 8 um metal gate PMOS process (metal width = 0.30 mil / 8.0 um, metal spacing = 0.35 mil / 9.0 um, diffusion width = 0.25 mil / 6.0 um, diffusion spacing = 0.35 mil / 9.0 um).
The TMS0800 uses a standard 0.6” wide 28-pin DIP (Dual In-line Package with a 0.1” / 2.54 mm lead pitch).
|1||O||Segment driver D||28||O||Segment driver C|
|2||O||Segment driver E||27||O||Segment driver B|
|3||O||Segment driver F||26||O||Segment driver A|
|4||O||Segment driver G||25||O||Segment driver DP|
|5||IO||n.c. (SH/LV)||24||O||Digit driver 1 (sign)|
|6||I||Key-matrix input P||23||O||Digit driver 2 (MSD)|
|7||I||Key-matrix input O||22||O||Digit driver 3|
|8||I||Key-matrix input N||21||O||Digit driver 4|
|9||I||Test (VSS)||20||O||Digit driver 5|
|10||O||Digit scan DK||19||O||Digit driver 6|
|11||V||Negative Voltage VDD||18||O||Digit driver 7|
|12||V||Negative Voltage VGG||17||O||Digit driver 8|
|13||n.c. (OSC Out)||16||O||Digit driver 9 (LSD)|
|14||I||Clock||15||V||Common Voltage VSS|
|The Segment drivers A-G and DP (Decimal Point) are
connected to the display in the pictured way.
The optional SH/LV signal can be configured as Segment H or Low Voltage indicator but is not in use with the known applications.
The keyboards of all calculators based on the TMS0800 family consist of a x/y-matrix connected to nine digit-driver outputs and the key-matrix inputs KN, KO and KP.
The TMS0800 integrates a timer to shut off the display after a certain amount of time with the calculator not in use, the reset of the timer can be accomplished either with an extra [D] key connected between the digit scan DK signal and the key-matrix input O line or simply by shorting DK output with the KN input.
Example for the TI-1500:
Calculators based on the TMS0800 make use of a 9-digit LED-display with common cathode architecture.
Learn more about the TMS0800 with Ken Shirriff's animated simulator for the TMS0800:
TI-2500 II (w/o [%]-key)
• TMC0805 Simulator: Sinclair Scientific
If you have additions to the above datasheet please email: firstname.lastname@example.org.
© Joerg Woerner, February 02, 2001. No reprints
without written permission.