Characterization of Single-chip Calculator Circuits - TMS0800 Product Family

The DCM-50A Platform supports the Characterization of TMS0800 Devices in its middle TMS0800 Textool Test Socket with the voltages V_SS set to 10.0V and V_GG set to -5.8V, accordingly.

TMS0801NC

Device-under-Test:

Keyboard: The Canon LE-84 makes use of a keyboard assembly with 18 conductive rubber switches switches arranged in a 9*2 matrix with the rows connected to the D1-D9 Outputs (Display Scan) and the columns connected to the KN and KO Inputs of the TMS0801NC single-chip calculator circuit. The Timeout feature of the TMS0801NC is disabled with a hard-wired connection between DK and KN on the Main-PCBB.

Keyboard Matrix of the Canon LE-84:

Display Layout:

The Output Decoder PLA of the TMS0801NC is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Timeout: The TMS0801NC implements a so-called Timeout feature. When no key presses are detected for about 20 seconds, the display blanks out and shows only a '-' in the leftmost digit to reduce power consumption of the calculator. Timeout is recoverable with an optional [D] key connected between the WDK Output and either the KN or KO Inputs, or pressing any key assigned to the keyboard scan matrix D8, D9/KN, KO, KP. We captured with a Digilent Digital Discovery Logic Analyzer connected to a TMS0801NC and operated in the DCM-50A Platform, the transition between normal operation and Timeout, before returning with pressing the [C] key back to normal operation. The TMS0801NC actually "remembered" the previous content of the display before clearing it due to the [C] key, the optional [D] key would have preserved the previous calculation.

Calculating overflow or a division of a positive or negative number by zero results in a "Flashing display". We measured a Flash-Frequency of about 1 Hz with a duty cycle of 50% but noticed that the display shows briefly '90000'. In a dim room you can actually see the phenomena with bare eyes.

Scanning: Display and keyboard scanning is performed in D9 → D1 direction at a rate of about 370 Hz with the Digits and Segments blanked at State S1 and State S11:

TMS0803NC

Device-under-Test:

Keyboard: The TI-2500-II makes use of a keyboard assembly with 19 Klixon™ hermetic snap action switches mounted on a printed circuit board (PCB). The switches are arranged in a 9*3 matrix with the rows connected to the D1-D9 Outputs (Display Scan) and the columns connected to the KN, KO and KP Inputs of the TMS0803NC single-chip calculator circuit. The Timeout feature of the TMS0803NC is disabled with a hard-wired connection between DK and KP on the Main-PCB.

Keyboard Matrix of the TI-2500-II:

Display Layout:

The Output Decoder PLA of the TMS0803NC is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Note: The DIS206C Display module has Segment B, Segment C and the Decimal Point (Segment DP) of the leftmost digit not bonded out.

Timeout: The TMS0803NC implements a so-called Timeout feature. When no key presses are detected for about 20 seconds, the display blanks out and shows only a '-' in the leftmost digit to reduce power consumption of the calculator. Timeout is recoverable with an optional [D] key connected between the WDK Output and either the KN or KO Inputs, or pressing any key assigned to the keyboard scan matrix D8, D9/KN, KO, KP. We captured with a Digilent Digital Discovery Logic Analyzer connected to a TMS0803NC and operated in the DCM-50A Platform, the transition between normal operation and Timeout, before returning with pressing the [C] key back to normal operation. The TMS0803NC actually "remembered" the previous content of the display before clearing it due to the [C] key, the optional [D] key would have preserved the previous calculation.

Scanning: Display and keyboard scanning is performed in D9 → D1 direction at a rate of about 370 Hz with the Digits and Segments blanked at State S1 and State S11:

TMC0805NC

Device-under-Test:

Keyboard: The Sinclair Scientific makes use of short-travel keys to push small metal discs against two contacts etched on the main printed circuit board (PCB). A separator plate keeps the metal plate holding the discs isolated from the electronics of the calculator. The switches are arranged in a 9*2 matrix with the rows connected to the D1-D9 Outputs (Display Scan) and the columns connected to the KN and KO Inputs of the TMC0805NC single-chip calculator circuit. The Timeout feature of the TMS0800 Product Family is not implemented in the TMC0805NC.

Keyboard Matrix of the Sinclair Scientific:

Display Layout:

The Digit Outputs D9 (leftmost Digit) to D1 (right most Digit) of the TMC0805NC are not connected directly to the physical Digit positions of the Full-custom Display module:

Note: The TMC0805 chip outputs in Digit Position D8 (ES - Exponent Sign) an '0' for positive Exponents and a '-' for negative Exponents. A hardwired connection on the Sinclair Scientific PCB disables Digit 8 if Segment A is activated, hence will the display be blanked for positive Exponents.

The Output Decoder PLA of the TMC0805NC is programmed for 7-Segment displays with the following Output Assignments:

Note: The decimal point is hardwired in the Sinclair Scientific and never output from the TMC0805 chip.

Display Fonts:

Timeout: The so-called Timeout feature used with the TMS0800 Product Family is not implemented in the TMS0805NC programming.

Scanning: Display and keyboard scanning is performed in D9 → D1 direction at a rate of about 370 Hz with the Digits and Segments blanked at State S1 and State S11:

TMC0806NC

Device-under-Test:

Keyboard: The Exactra 19 makes use of a keyboard assembly with 18 Klixon™ hermetic snap action switches mounted on a printed circuit board (PCB). The switches are arranged in a 9*3 matrix with the rows connected to the D1-D9 Outputs (Display Scan) and the columns connected to the KN, KO and KP Inputs of the TMC0806NC single-chip calculator circuit. The Timeout feature of the TMC0806NC is disabled with a hard-wired connection between DK and KP on the Main-PCB.

Keyboard Matrix of the Exactra 19:

Display Layout:

The Digit Outputs D9 (leftmost Digit) to D1 (right most Digit) of the TMC0806NC are not connected directly to the physical Digit positions of the DISEX19 Display module:

Note: The TMC0806 chip outputs in the unused Digit Positions D2 and D1 always '00'.

The Output Decoder PLA of the TMC0806NC is programmed for 7-Segment displays with the following Output Assignments:

Note: The TMC0806 chip outputs in the leftmost Digit Position D9 Segments G and H together to allow for a discrete LED chip instead a full Seven-Segment LED chip in the leading position of the Display module.

Display Fonts:

Timeout: The TMC0806NC implements a so-called Timeout feature. When no key presses are detected for about 20 seconds, the display blanks out and shows only a '-' in the leftmost digit to reduce power consumption of the calculator. Timeout is recoverable with an optional [D] key connected between the WDK Output and either the KN or KO Inputs, or pressing any key assigned to the keyboard scan matrix D8, D9/KN, KO, KP.

Scanning: Display and keyboard scanning is performed in D9 → D1 direction at a rate of about 370 Hz without Digit- and Segment-Blanking:

TMS0807NC

Device-under-Test:

Keyboard: The Canon LE-85 makes use of a keyboard assembly with 20 conductive rubber switches switches arranged in a 9*3 matrix with the rows connected to the D1-D9 Outputs (Display Scan) and the columns connected to the KN, KO and KP Inputs of the TMS0807NC single-chip calculator circuit. The Timeout feature of the TMS0807NC is disabled with a hard-wired connection between DK and KN on the Main-PCB.

Keyboard Matrix of the Canon LE-85:

Display Layout:

The Output Decoder PLA of the TMS0807NC is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Timeout: The TMS0807NC implements a so-called Timeout feature. When no key presses are detected for about 20 seconds, the display blanks out and shows only a '-' in the leftmost digit to reduce power consumption of the calculator. Timeout is recoverable with an optional [D] key connected between the WDK Output and either the KN or KO Inputs, or pressing any key assigned to the keyboard scan matrix D8, D9/KN, KO, KP. We captured with a Digilent Digital Discovery Logic Analyzer connected to a TMS0803NC and operated in the DCM-50A Platform, the transition between normal operation and Timeout, before returning with pressing the [C] key back to normal operation. The TMS0807NC actually "remembered" the previous content of the display before clearing it due to the [C] key, the optional [D] key would have preserved the previous calculation.

Scanning: Display and keyboard scanning is performed in D9 → D1 direction at a rate of about 370 Hz with the Digits and Segments blanked at State S1 and State S11: