Stop Thief

chip top marked TMS0980NLL MP6101B DBT 8005 SINGAPORE
die labeled 0980B-01A

3 7-segment LEDs (# ##)
15 pushbuttons - 0-9, Off, On, T, A, C

         keypad layout
--------------------------------------
         Pin 12   Pin 18   +9V
Pin  6      1       2      Off
Pin 10      3       4      On
Pin  9      5       6       T
Pin  8      7       8       A
Pin  7      9       0       C

Pin 1 -  D3    - Digit 1 (rightmost)
Pin 2 -  D2    - Digit 2 (center)
Pin 3 -  D1    - Digit 3 (leftmost)
Pin 4 -  INIT? - N/C
Pin 5 -  VDD   - 9v battery negative
Pin 6 -  K3    - keypad row 4
Pin 7 -  K8    - keypad row 0
Pin 8 -  K4    - keypad row 1
Pin 9 -  K2    - keypad row 2
Pin 10 - K1    - keypad row 3
Pin 11 - O6    - Segment D
Pin 12 - O5    - Segment E
Pin 13 - O0    - Segment G
Pin 14 - O4    - Segment A
Pin 15 - O1    - capacitor and diode to speaker
Pin 16 - O3    - Segment C
Pin 17 - O7    - Segment B
Pin 18 - O2    - Segment F
Pin 19 - OSC?  - N/C
Pin 20 - VSS   - 9v battery positive
Pin 21 - D11?  - N/C
Pin 22 - D10?  - N/C
Pin 23 - D9    - Pins 23-28 are connected together and to the speaker
Pin 24 - D8    - Speaker
Pin 25 - D7    - Speaker
Pin 26 - D6    - Speaker
Pin 27 - D5    - Speaker
Pin 28 - D4    - Speaker

Output O PLA
BDEACFpG
--------
11111100 0
00100100 1
11110001 2
11011001 3
10001101 4
01011101 5
01101101 6
10011000 7
11111101 8
10011101 9
01110100 C
11101001 d
00110101 F
01111100 G
01100101 t
00000000