Texas Instruments TI-30

chip top marked TMC0981NL MFT 7901 SINGAPORE
die labeled 0980B-81F

9 7-segment LEDs (leftmost only has segments DP, B, G and F)
40 pushbuttons - 0-9, ., Off, On/C, 1/x, x^2, sqrt, INV,
sin, cos, tan, DRG, K, EE, log, lnx, y^x, pi, %, (, ),
/, X, -, +, =, STO, RCL, SUM, EXC, +/-

                        keypad layout
-------------------------------------------------------
          Pin  9  Pin  7   Pin  8  Pin  6   Pin 10
Pin  4      1/x     x^2     sqrt     Off     On/C
Pin 12      INV     sin     cos      tan     DRG
Pin 18       K      EE      log      lnx     y^x
Pin 14      pi       %       (        )        /
Pin 17      STO      7       8        9        X
Pin 16      RCL      4       5        6        -
Pin 13      SUM      1       2        3        +
Pin 11      EXC      0       .       +/-       =

Pin 1  - Digit 7
Pin 2  - Digit 8
Pin 3  - Digit 9 (only segments DP, B, G and F)
Pin 4  - 9V battery + / Keypad Row 6 / Pin 20
Pin 5  - 9V battery -
Pin 6  - Keypad Column 4
Pin 7  - Keypad Column 2
Pin 8  - Keypad Column 3
Pin 9  - Keypad Column 1
Pin 10 - Keypad Column 5
Pin 11 - Keypad Row 1 / Segment DP
Pin 12 - Keypad Row 7 / Segment B
Pin 13 - Keypad Row 2 / Segment G
Pin 14 - Keypad Row 5 / Segment D
Pin 15 - Segment A
Pin 16 - Keypad Row 3 / Segment F
Pin 17 - Keypad Row 4 / Segment E
Pin 18 - Keypad Row 6 / Segment C
Pin 19 - N/C
Pin 20 - 9V battery + / Keypad Row 8 / Pin 4
Pin 21 - N/C
Pin 22 - N/C
Pin 23 - Digit 1
Pin 24 - Digit 2
Pin 25 - Digit 3
Pin 26 - Digit 4
Pin 27 - Digit 5
Pin 28 - Digit 6

Output O PLA
11111110 0
10011000 1
11110011 2
11011011 3
10011101 4
01011111 5
01111111 6
10011010 7
11111111 8
11011111 9
00010001 -
01110111 E
00110001 r
01111001 o
10010100 "
00000000