Characterization of Single-chip Calculator Circuits - TMS0970 Family

The DCM-50A Platform supports the Characterization of 28-pin TMS0970 and TMC0900 Devices in its right-most TMS1000 Textool Test Socket using an additional TMS0900 Adapter and the voltages V_SS set to 9.5V and V_DD/V_GG set to -5.5V, accordingly. The TMS0900 Adapter supports a maximum of 9 digit drivers but allows to jumper them to any set of the maximum of 11 digit drivers of the TMS0970 silicon chip. Pleas notice that layout of the TMS0900 Adapter maps the nine Digit Outputs D9 (MSD) to D1 (LSD) of the device under test to the corresponding R10 to R2 Outputs of the TMS1000 socket, hence creating an MSD-aligned 7-Segment Display on the DCM-50A Platform.

TMS0972NL

Device-under-Test:

Keyboard: The TI-1200 makes use of a keyboard with snap-action dome switches arranged in an 5*4 matrix with the rows connected to the scanning O1-O5 Segment Outputs (Display Scan) and the columns connected to the K1-K8 Inputs (Keyboard Scan) of the TMS0972NL single-chip calculator circuit. Please notice that the otherwise identical TI-1250 uses a 6*4 keyboard matrix with the O7 Segment Output scanning the extra row of [MC], [MR], [M−], and [M+] keys. Some TI-1200 even use the 6*4 keyboard and just hide the extra functionality including the [+/−] key with the face plate.

Keyboard Matrix of the TI-1200:

Display: The TI-1200 makes use of a DIS233G Nine-Digit Calculator Numeric Seven-Segment LED Display module without the leading digit populated directly connected to the corresponding Digit Output pins R0 to R7 (LSD to sign/MSD) and Segment Output pins O0 to O7 (SA to SDP).

Display Layout:

The Output Decoder PLA of the TMS0972NL (DIP-28) is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Overflow conditions of the TI-1200 like dividing a number by zero are resulting in a "Flashing" display on the calculator. We analyzed the implementation of the "Flashing" display with a Digilent Digital Discovery Logic Analyzer connected to a TMS0972NL operated in the DCM-50A Platform while performing certain math calculations in parallel with an actual TI-1200.

The TMS0972 alternates in this condition between two completely different Display Scanning Cycles, resulting in a Flash-Frequency of about 5 Hz:

Scanning: Display and keyboard scanning is performed in O7 → O0 direction at a rate of about 220 Hz with the O0 State stretched slightly:

Please notice that the TMS0972 is outputting an active Memory Indicator despite the left most digit of the display not populated.

TMS0972NL

Device-under-Test:

Keyboard: The TI-1250 makes use of a keyboard with snap-action dome switches arranged in an 6*4 matrix with the rows connected to the scanning O1-O5, O7 Segment Outputs (Display Scan) and the columns connected to the K1-K8 Inputs (Keyboard Scan) of the TMS0972NL single-chip calculator circuit.

Keyboard Matrix of the TI-1250:

Display: The TI-1250 makes use of a DIS233G Nine-Digit Calculator Numeric Seven-Segment LED Display module without the leading digit populated directly connected to the corresponding Digit Output pins R0 to R7 (LSD to sign/MSD) and Segment Output pins O0 to O7 (SA to SDP).

Display Layout:

The Output Decoder PLA of the TMS0972NL (SPDIP-28) is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Overflow conditions of the TI-1200 like dividing a number by zero or changing the sign of a number with 8 digits before the decimal point are resulting in a "Flashing" display on the calculator. We analyzed the implementation of the "Flashing" display with a Digilent Digital Discovery Logic Analyzer connected to a TMS0972NL operated in the DCM-50A Platform while performing certain math calculations in parallel with an actual TI-1250.

The TMS0972 alternates in this condition between two completely different Display Scanning Cycles, resulting in a Flash-Frequency of about 5 Hz:

Scanning: Display and keyboard scanning is performed in O7 → O0 direction at a rate of about 220 Hz with the O0 State stretched slightly:

Please notice that the TMS0972 is outputting an active Memory Indicator despite the left most digit of the display not populated.

TMS0973NL

Device-under-Test:

Keyboard: The Electra Bearcat 210 (BC-210) Radio Scanner makes use of a keyboard with twenty push-button switches arranged in an 8*3 matrix with the rows connected to the scanning O0-O7 Segment Outputs (Display Scan) and the columns connected to the K2-K8 Inputs (Keyboard Scan) of the TMS0973NL single-chip calculator circuit. The K1 Input is used during the R10 Digit Time together with the Segment Outputs to communicate with the Synthesizer chip through its shift register.

Keyboard Matrix of the Electra Bearcat 210:

Display: The Electra Bearcat 210 makes use makes use ten discrete Common-Cathode Seven-Segment LED Displays soldered onto a small printed circuit board (PCB) and controlled with 10 additional driver transistors for the cathodes from the corresponding Output pins R0 to R9 and 8 additional driver transistors for the segments SA to SDP from the Output pins O0 to O7.

Display Layout:

The Output Decoder PLA of the TMS0973NL is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Scanning: Display and keyboard scanning is performed in O7 → O0 direction at a rate of about 160 Hz. During communication with the Synthesizer chip of the BC-210 both display and keyboard scanning is paused for about 60 ms and the R10 Output activated. The O0 to O7 Outputs are used during R10 Digit Time together with the K1 Input to exchange data with the shift register of the Synthesizer chip. During normal display scanning both O7 and O0 States are stretched slightly:

TMS0974NL

Device-under-Test:

Keyboard: The TI-1270 makes use of a keyboard with snap-action dome switches arranged in an 6*4 matrix with the rows connected to the scanning O1-O5 and O7 Segment Outputs (Display Scan) and the columns connected to the K1-K8 Inputs (Keyboard Scan) of the TMS0974NL single-chip calculator circuit.

Keyboard Matrix of the TI-1270:

Display: The TI-1270 makes use of a DIS233G Nine-Digit Calculator Numeric Seven-Segment LED Display module without the leading digit populated directly connected to the corresponding Digit Output pins R0 to R7 (LSD to sign/MSD) and Segment Output pins O0 to O7 (SA to SDP).

Display Layout:

The Output Decoder PLA of the TMS0974NL is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Overflow conditions of the TI-1270 like dividing a number by zero or trying to calculate the square root of a negative number are resulting in a "Flashing" display on the calculator. We analyzed the implementation of the "Flashing" display with a Digilent Digital Discovery Logic Analyzer connected to a TMS0974NL operated in the DCM-50A Platform while performing certain math calculations in parallel with an actual TI-1270.

The TMS0974 alternates in this condition between two completely different Display Scanning Cycles, resulting in a Flash-Frequency of about 4 Hz:

Scanning: Display and keyboard scanning is performed in O7 → O0 direction at a rate of about 220 Hz with the O0 State stretched slightly:

TMS975NL

Device-under-Test:

Keyboard: The Little Professor makes use of a keyboard with snap-action dome switches arranged in an 4*4 matrix with with the rows connected to the scanning O1-O4 Segment Outputs (Display Scan) and the columns connected to the K1-K8 Inputs (Keyboard Scan) of the TMS0975NL single-chip calculator circuit. While the Little Professor uses the keyboard of the TI-1200 with a 5x4 matrix with the top row masked by the face plate, is the four-position [Level] sliding switch connected to the corresponding O5 Segment Output.

Keyboard Matrix of the Little Professor:

Display: The Little Professor makes use of a DIS713 Nine-Digit Seven-Segment LED Display module directly connected to the corresponding Digit Output pins R0 to R8 (LSD to MSD) and Segment Output pins O0 to O6 (SA to SG). The DIS713 is a modification of the DIS233G Nine-Digit Calculator Numeric Seven-Segment LED Display module with the 3^rd digit position from the left replaced with a "Star" to display +, −, ×, and ÷ and the 6^th position replaced with just two bars to display =. The Decimal Point is not used with the DIS713.

Display Layout:

The Output Decoder PLA of the TMS0975NL (DIP-28) is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Looking closer into the Display Fonts used with the Little Professor, you'll notice a total of 18 different patterns (10 Numbers, 4 Operands, Equal Sign, E for Error, Segment G for Idle, and Blank) - beyond the capabilities of the PLA used for the Output Decoder of the TMS0970 and supporting only 16 different inputs.

We looked into the differences between the possible PLA implementation and its visual representation on the Little Professor LED display with a Digilent Digital Discovery Logic Analyzer connected to a TMS0975NL AP operated in the DCM-50A Platform while playing in parallel with an actual Little Professor educational toy.

After the tenth math problem the score is "Flashing" on the LED display of the Little Professor. The TMS0975NL AP pauses between the Display Scanning Cycles with a blanked display having only Segment B enabled, resulting in a Flash-Frequency of about 2.5 Hz at a CK Frequency of 150 kHz:

Entering a wrong answer results in the "EEE" message on the Little Professor LED display. The TMS0975NL AP is actually outputting the Segment Pattern for "EEE" while the later TMS0975NL GCS is outputting the number 666 but doesn't scan Segment C resulting in the "EEE" displayed.

During the transition from displaying the math problem and entering a wrong answer, the Little Professor pauses for a short time and keep the pace of its Display Scanning Cycle while the later TMS0975NL GCS switches into a much faster Display Scanning Cycle.

In the moment the pressed key is detected, the Display Scanning Cycle stops immediately and "freezes" the last active Segment Scanning line to debug the key. Example shows pressing [8] which is connected between O4 Segment E Output and K2 Input (KP on DCM-50A Platform).

To save battery power while not in use, the Little Professor changes after a certain time into an Idle-Mode displaying just a "-" in Digit Position R2. With R2 used for Numbers, the "-" correspondents to only Segment G activated and the Digilent Digital Discovery demonstrates this behavior. As of today we can't explain this discrepancy with the suspected PLA implementation of the TMS0975NL AP.

Scanning: Display and keyboard scanning is performed in O6 → O0 direction at a rate of about 80 Hz with one Blank State after O0. The following timing was measured while displaying " 3+ 4=":

TMS975NL

Device-under-Test:

Keyboard: The Little Professor makes use of a keyboard with snap-action dome switches arranged in an 4*4 matrix with with the rows connected to the scanning O1-O4 Segment Outputs (Display Scan) and the columns connected to the K1-K8 Inputs (Keyboard Scan) of the TMS0975NL single-chip calculator circuit. While the Little Professor uses the keyboard of the TI-1200 with a 5x4 matrix with the top row masked by the face plate, is the four-position [Level] sliding switch connected to the corresponding O5 Segment Output.

Keyboard Matrix of the Little Professor:

Display: The Little Professor makes use of a DIS713 Nine-Digit Seven-Segment LED Display module directly connected to the corresponding Digit Output pins R0 to R8 (LSD to MSD) and Segment Output pins O0 to O6 (SA to SG). The DIS713 is a modification of the DIS233G Nine-Digit Calculator Numeric Seven-Segment LED Display module with the 3^rd digit position from the left replaced with a "Star" to display +, −, ×, and ÷ and the 6^th position replaced with just two bars to display =. The Decimal Point is not used with the DIS713.

Display Layout:

The Output Decoder PLA of the TMS0975NL (DIP-28) is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Looking closer into the Display Fonts used with the Little Professor, you'll notice a total of 18 different patterns (10 Numbers, 4 Operands, Equal Sign, E for Error, Segment G for Idle, and Blank) - beyond the capabilities of the PLA used for the Output Decoder of the TMS0970 and supporting only 16 different inputs.

We looked into the differences between the possible PLA implementation and its visual representation on the Little Professor LED display with a Digilent Digital Discovery Logic Analyzer connected to a TMS0975NL BP operated in the DCM-50A Platform while playing in parallel with an actual Little Professor educational toy.

After the tenth math problem the score is "Flashing" on the LED display of the Little Professor. The TMS0975NL BP pauses between the Display Scanning Cycles with a blanked display having only Segment B enabled, resulting in a Flash-Frequency of about 1.25 Hz at a CK Frequency of 150 kHz:

Entering a wrong answer results in the "EEE" message on the Little Professor LED display. The TMS0975NL BP is like the later TMS0975NL GCS actually outputting the Segment Pattern for the number 666 but doesn't scan Segment C resulting in the "EEE" displayed. We observed with the TMS0975NL BP and GCS the following Display Scanning Sequence: SG on, SF on, SE on, SD on, SC skipped for a dummy SA off, SB off, and SA on forming the numbers 6.

During the transition from displaying the math problem and entering a wrong answer, the Little Professor pauses for a short time and switches into a much faster Display Scanning Cycle while the earlier TMS0975NL AP keep the pace of its Display Scanning Cycle.

In the moment the pressed key is detected, the Display Scanning Cycle stops immediately and "freezes" the last active Segment Scanning line to debug the key. Example shows pressing [8] which is connected between O4 Segment E Output and K2 Input (KP on DCM-50A Platform).

To save battery power while not in use, the Little Professor changes after a certain time into an Idle-Mode displaying just a "-" in Digit Position R2. With R2 used for Numbers, the "-" correspondents to only Segment G activated and the Digilent Digital Discovery demonstrates this behavior. As of today we can't explain this discrepancy with the suspected PLA implementation of the TMS0975NL BP.

Scanning: Display and keyboard scanning is performed in O6 → O0 direction at a rate of about 60 Hz with one Blank State after O0 and slightly different timing for the individual OX States depending on the content of the display. The following timing was measured while displaying " 1+ 4=":

TMS975NL

Device-under-Test:

Keyboard: The Little Professor makes use of a keyboard with snap-action dome switches arranged in an 4*4 matrix with with the rows connected to the scanning O1-O4 Segment Outputs (Display Scan) and the columns connected to the K1-K8 Inputs (Keyboard Scan) of the TMS0975NL single-chip calculator circuit. The Little Professor uses the keyboard of the TI-1200 with a 5x4 matrix but the top row is masked by the face plate. The four-position [Level] sliding switch connected to the O7 Segment Output.

Keyboard Matrix of the Little Professor:

Display: The Little Professor makes use of a DIS713 Nine-Digit Seven-Segment LED Display module directly connected to the corresponding Digit Output pins R0 to R8 (LSD to MSD) and Segment Output pins O0 to O6 (SA to SG). The DIS713 is a modification of the DIS233G Nine-Digit Calculator Numeric Seven-Segment LED Display module with the 3^rd digit position from the left replaced with a "Star" to display +, −, ×, and ÷ and the 6^th position replaced with just two bars to display =. The Decimal Point is not used with the DIS713.

Display Layout:

The Output Decoder PLA of the TMS0975NL (SPDIP-28) is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Looking closer into the Display Fonts used with the Little Professor, you'll notice a total of 18 different patterns (10 Numbers, 4 Operands, Equal Sign, E for Error, Segment G for Idle, and Blank) - beyond the capabilities of the PLA used for the Output Decoder of the TMS0970 and supporting only 16 different inputs. Sean Riddle analyzed the physical implementation of the TMS0975NL CSP PLA and it uses indeed only 16 different patterns:

We analyzed the differences between the actual PLA implementation and its visual representation on the Little Professor LED display with a Digilent Digital Discovery Logic Analyzer connected to a TMS0975NL CSP operated in the DCM-50A Platform while playing in parallel with an actual Little Professor educational toy.

After the tenth math problem the score is "Flashing" on the LED display of the Little Professor. The TMS0975NL CSP pauses between the Display Scanning Cycles with a blanked display having only Segment B enabled, resulting in a Flash-Frequency of about 1 Hz at a CK Frequency of 150 kHz:

Entering a wrong answer results in the "EEE" message on the Little Professor LED display. The TMS0975NL CSP is actually outputting the Segment Pattern for the number 666 but doesn't scan Segment C resulting in the "EEE" displayed.

During the transition from displaying the math problem and entering a wrong answer, the Little Professor pauses for a short time and switches into a much faster Display Scanning Cycle.

In the moment the pressed key is detected, the Display Scanning Cycle stops immediately and "freezes" the last active Segment Scanning line to debug the key. Example shows pressing [8] which is connected between O4 Segment E Output and K2 Input (KP on DCM-50A Platform).

To save battery power while not in use, the Little Professor changes after a certain time into an Idle-Mode displaying just a "-" in Digit Position R2. With R2 used for Numbers, the "-" correspondents to only Segment G activated and the Digilent Digital Discovery demonstrates this behavior. As of today we can't explain this discrepancy with the actual PLA implementation of the TMS0975NL CSP.

Scanning: Display and keyboard scanning is performed in O7 → O0 direction at a rate of about 60 Hz with slightly different timing for the individual OX States depending on the content of the display. The following timing was measured while displaying " 5+ 4=":

TMS975NL

Device-under-Test:

Keyboard: The Little Professor makes use of a keyboard with snap-action dome switches arranged in an 4*4 matrix with with the rows connected to the scanning O1-O4 Segment Outputs (Display Scan) and the columns connected to the K1-K8 Inputs (Keyboard Scan) of the TMS0975NL single-chip calculator circuit. The Little Professor uses the keyboard of the TI-1200 with a 5x4 matrix but the top row is masked by the face plate. The four-position [Level] sliding switch connected to the O7 Segment Output.

Keyboard Matrix of the Little Professor:

Display: The Little Professor makes use of a DIS713 Nine-Digit Seven-Segment LED Display module directly connected to the corresponding Digit Output pins R0 to R8 (LSD to MSD) and Segment Output pins O0 to O6 (SA to SG). The DIS713 is a modification of the DIS233G Nine-Digit Calculator Numeric Seven-Segment LED Display module with the 3^rd digit position from the left replaced with a "Star" to display +, −, ×, and ÷ and the 6^th position replaced with just two bars to display =. The Decimal Point is not used with the DIS713.

Display Layout:

The Output Decoder PLA of the TMS0975NL (SPDIP-28) is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Looking closer into the Display Fonts used with the Little Professor, you'll notice a total of 18 different patterns (10 Numbers, 4 Operands, Equal Sign, E for Error, Segment G for Idle, and Blank) - beyond the capabilities of the PLA used for the Output Decoder of the TMS0970 and supporting only 16 different inputs. Sean Riddle analyzed the physical implementation of the TMS0975NL GCS PLA and it uses indeed only 16 different patterns:

We analyzed the differences between the actual PLA implementation and its visual representation on the Little Professor LED display with a Digilent Digital Discovery Logic Analyzer connected to a TMS0975NL GCS operated in the DCM-50A Platform while playing in parallel with an actual Little Professor educational toy.

After the tenth math problem the score is "Flashing" on the LED display of the Little Professor. The TMS0975NL GCS pauses between the Display Scanning Cycles with a blanked display having only Segment B enabled, resulting in a Flash-Frequency of about 1 Hz at a CK Frequency of 150 kHz:

Entering a wrong answer results in the "EEE" message on the Little Professor LED display. The TMS0975NL GCS is actually outputting the Segment Pattern for the number 666 but doesn't scan Segment C resulting in the "EEE" displayed.

During the transition from displaying the math problem and entering a wrong answer, the Little Professor pauses for a short time and switches into a much faster Display Scanning Cycle.

In the moment the pressed key is detected, the Display Scanning Cycle stops immediately and "freezes" the last active Segment Scanning line to debug the key. Example shows pressing [8] which is connected between O4 Segment E Output and K2 Input (KP on DCM-50A Platform).

To save battery power while not in use, the Little Professor changes after a certain time into an Idle-Mode displaying just a "-" in Digit Position R2. With R2 used for Numbers, the "-" correspondents to only Segment G activated and the Digilent Digital Discovery demonstrates this behavior. As of today we can't explain this discrepancy with the actual PLA implementation of the TMS0975NL GCS.

Scanning: Display and keyboard scanning is performed in O7 → O0 direction at a rate of about 60 Hz with slightly different timing for the individual OX States depending on the content of the display. The following timing was measured while displaying " 0+ 3=":

TMC0907NL

Device-under-Test:

Keyboard: The WIZ-A-TRON makes use of a keyboard with snap-action dome switches arranged in an 4*4 matrix with with the rows connected to the scanning O1-O4 Segment Outputs (Display Scan) and the columns connected to the K1-K8 Inputs (Keyboard Scan) of the TMC0907NL single-chip calculator circuit.

Keyboard Matrix of the WIZ-A-TRON:

Display: The WIZ-A-TRON makes use of a DIS713 Nine-Digit Seven-Segment LED Display module directly connected to the corresponding Digit Output pins R0 to R8 (LSD to MSD) and Segment Output pins O0 to O6 (SA to SG). The DIS713 is a modification of the DIS233G Nine-Digit Calculator Numeric Seven-Segment LED Display module with the 3^rd digit position from the left replaced with a "Star" to display +, −, ×, and ÷ and the 6^th position replaced with just two bars to display =. The Decimal Point is not used with the DIS713.

Display Layout:

The Output Decoder PLA of the TMC0907NL is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Looking closer into the Display Fonts used with the WIZ-A-TRON, you'll notice a total of 18 different patterns (10 Numbers, 4 Operands, Equal Sign, E for Error, Segment G for Idle, and Blank) - beyond the capabilities of the PLA used for the Output Decoder of the TMS0970 and supporting only 16 different inputs. Sean Riddle analyzed the physical implementation of the TMC0907NL PLA and it uses indeed only 16 different patterns:

We analyzed the differences between the actual PLA implementation and its visual representation on the WIZ-A-TRON LED display with a Digilent Digital Discovery Logic Analyzer connected to a TMC0907NL operated in the DCM-50A Platform while playing in parallel with an actual WIZ-A-TRON educational toy.

After Power-up the WIZ-A-TRON is greeting the user with an Equal Sign in Digit Position R3. The TMC0907 is actually outputting the Segment Pattern for the number 8 but the DIS713 LED display is populated for this Digit Position with only the two bars forming the Equal Sign.

Entering a wrong answer results in the "EEE" message on the WIZ-A-TRON LED display. The TMC0907 is actually outputting the Segment Pattern for the number 666 but doesn't scan Segment C resulting in the "EEE" displayed.

Entering a correct answer results in a "Flashing" display on the WIZ-A-TRON. The TMC0907 alternates between two completely different Display Scanning Cycles, a blanked display uses only Segments B, C, D, and E scanning is preformed at a very low frequency.

To save battery power while not in use, the WIZ-A-TRON changes after a certain time into an Idle-Mode displaying just a "-" in Digit Position R2. With R2 used for Numbers, the "-" correspondents to only Segment G activated and the Digilent Digital Discovery demonstrates this behavior. As of today we can't explain this discrepancy with the actual PLA implementation of the TMC0907.

Scanning: Display and keyboard scanning is performed in O7 → O0 direction at a rate of about 160 Hz with slightly different timing for the individual OX States depending on the content of the display. The following timing was measured while displaying "12+34=":

TMC0907NL

Device-under-Test:

Keyboard: The WIZ-A-TRON makes use of a keyboard with snap-action dome switches arranged in an 4*4 matrix with with the rows connected to the scanning O1-O4 Segment Outputs (Display Scan) and the columns connected to the K1-K8 Inputs (Keyboard Scan) of the TMC0907NL single-chip calculator circuit.

Keyboard Matrix of the WIZ-A-TRON:

Display: The WIZ-A-TRON makes use of a DIS713 Nine-Digit Seven-Segment LED Display module directly connected to the corresponding Digit Output pins R0 to R8 (LSD to MSD) and Segment Output pins O0 to O6 (SA to SG). The DIS713 is a modification of the DIS233G Nine-Digit Calculator Numeric Seven-Segment LED Display module with the 3^rd digit position from the left replaced with a "Star" to display +, −, ×, and ÷ and the 6^th position replaced with just two bars to display =. The Decimal Point is not used with the DIS713.

Display Layout:

The Output Decoder PLA of the TMC0907NL is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

Looking closer into the Display Fonts used with the WIZ-A-TRON, you'll notice a total of 18 different patterns (10 Numbers, 4 Operands, Equal Sign, E for Error, Segment G for Idle, and Blank) - beyond the capabilities of the PLA used for the Output Decoder of the TMS0970 and supporting only 16 different inputs. Sean Riddle analyzed the physical implementation of the TMC0907NL PLA and it uses indeed only 16 different patterns:

We analyzed the differences between the actual PLA implementation and its visual representation on the WIZ-A-TRON LED display with a Digilent Digital Discovery Logic Analyzer connected to a TMC0907NL operated in the DCM-50A Platform while playing in parallel with an actual WIZ-A-TRON educational toy.

After Power-up the WIZ-A-TRON is greeting the user with an Equal Sign in Digit Position R3. The TMC0907 is actually outputting the Segment Pattern for the number 8 but the DIS713 LED display is populated for this Digit Position with only the two bars forming the Equal Sign.

Entering a wrong answer results in the "EEE" message on the WIZ-A-TRON LED display. The TMC0907 is actually outputting the Segment Pattern for the number 666 but doesn't scan Segment C resulting in the "EEE" displayed.

Entering a correct answer results in a "Flashing" display on the WIZ-A-TRON. The TMC0907 alternates between two completely different Display Scanning Cycles, a blanked display uses only Segments B, C, D, and E scanning is preformed at a very low frequency.

To save battery power while not in use, the WIZ-A-TRON changes after a certain time into an Idle-Mode displaying just a "-" in Digit Position R2. With R2 used for Numbers, the "-" correspondents to only Segment G activated and the Digilent Digital Discovery demonstrates this behavior. As of today we can't explain this discrepancy with the actual PLA implementation of the TMC0907.

Scanning: Display and keyboard scanning is performed in O7 → O0 direction at a rate of about 160 Hz with slightly different timing for the individual OX States depending on the content of the display. The following timing was measured while displaying "12+34=":