| 666881 | HEF4001BT-Q100 | Quad 2-input NOR gate | NXP Semiconductors |
| 666882 | HEF4001BU | Quadruple 2-input NOR gate | Philips |
| 666883 | HEF4001UB | Quadruple 2-input NOR gate | Philips |
| 666884 | HEF4001UBD | Quadruple 2-input NOR gate | Philips |
| 666885 | HEF4001UBDB | Quadruple 2-input NOR gate | Philips |
| 666886 | HEF4001UBF | Quadruple 2-input NOR gate | Philips |
| 666887 | HEF4001UBN | Quadruple 2-input NOR gate | Philips |
| 666888 | HEF4001UBP | Quadruple 2-input NOR gate | Philips |
| 666889 | HEF4001UBPB | Quadruple 2-input NOR gate | Philips |
| 666890 | HEF4001UBT | Quadruple 2-input NOR gate | Philips |
| 666891 | HEF4001UBU | Quadruple 2-input NOR gate | Philips |
| 666892 | HEF4002B | Dual 4-input NOR gate | Philips |
| 666893 | HEF4002BD | Dual 4-input NOR gate | Philips |
| 666894 | HEF4002BF | Dual 4-input NOR gate | Philips |
| 666895 | HEF4002BN | Dual 4-input NOR gate | Philips |
| 666896 | HEF4002BP | Dual 4-input NOR gate | NXP Semiconductors |
| 666897 | HEF4002BP | Dual 4-input NOR gate | Philips |
| 666898 | HEF4002BT | Dual 4-input NOR gate | Nexperia |
| 666899 | HEF4002BT | Dual 4-input NOR gate | NXP Semiconductors |
|
| 666900 | HEF4002BT | Dual 4-input NOR gate | Philips |
| 666901 | HEF4006B | 18-stage static shift register | Philips |
| 666902 | HEF4006BD | 18-stage static shift register | Philips |
| 666903 | HEF4006BF | 18-stage static shift register | Philips |
| 666904 | HEF4006BN | 18-stage static shift register | Philips |
| 666905 | HEF4006BP | 18-stage static shift register | Philips |
| 666906 | HEF4006BT | 18-stage static shift register | Philips |
| 666907 | HEF4007UB | Dual complementary pair and inverter | Philips |
| 666908 | HEF4007UBD | Dual complementary pair and inverter | Philips |
| 666909 | HEF4007UBF | Dual complementary pair and inverter | Philips |
| 666910 | HEF4007UBN | Dual complementary pair and inverter | Philips |
| 666911 | HEF4007UBP | Dual complementary pair and inverter | NXP Semiconductors |
| 666912 | HEF4007UBP | Dual complementary pair and inverter | Philips |
| 666913 | HEF4007UBT | Dual complementary pair and inverter | Nexperia |
| 666914 | HEF4007UBT | Dual complementary pair and inverter | NXP Semiconductors |
| 666915 | HEF4007UBT | Dual complementary pair and inverter | Philips |
| 666916 | HEF4008 | 4-bit binary full adder | Philips |
| 666917 | HEF4008B | 4-bit binary full adder | Philips |
| 666918 | HEF4008BD | 4-bit binary full adder | Philips |
| 666919 | HEF4008BF | 4-bit binary full adder | Philips |
| 666920 | HEF4008BN | 4-bit binary full adder | Philips |
