Friden 1166 Circuit Board #4

Board #4 (along with Board #5) in the Friden 1166 calculator contains sequencing and control logic for the calculator. The board is substantially different than the same board in the 1160 calculator. This board is a bit more complex than the same board in the 1160 due to the modifications to the logic required to implement the improvements made in the 1166. Circuit Board #4 is specific only to the 1166, and is not interchangeable with Board #4 from the 1160 calculator. The circuit board has "1166" etched on the upper right hand corner of the board to make it clear that it must only be installed in the 1166 calculator. The various improvements to the 1166 over the 1160 account for the differences in the logic on Board #4 and Board #5.

Board #4 contains 29 integrated circuits. Three of the IC's are TTL 7474 Dual D-Type Flip Flops made by Texas Instruments, and the remaining 19 ICs are DTL devices, made by Texas Instruments and Motorola. Along with the ICs, there are 26 diodes, 16 resistors and one capacitor.

The bare circuit board has Part # 7016707 Revision 1. The completed assembly has Part # 7016708.