Hold That Bit - The Motorola MC358 J-K Flip-Flop

This artwork is based on a micro-image of one of the very first computer chips. The actual chip is in the lower left corner of the artwork, and it's over fifty years old. This was a chip that could store a single bit of information. The picture below shows an x-ray view of the chip. The "chip" that you see is actually the package for the true chip. The silicon computer chip is attached to a Header and covered by the Can, so you can't see it. It is protected in the package and is connected to the outside world with Interconnect Wires that attach the chip's pads to the Leads (the tops of three of the leads are visible at the left side of the image) that allow the package to be plugged into a circuit board. This MC358A J-K Flip-Flop chip was made by Motorola.

The 358 chip contains a simple circuit called a J-K Flip-Flop. Flip Flops used sequential logic and were bistable. The J-K Flip Flop is the most common and useful of the Flip Flop Circuits. Flip-Flops consisted of a couple of transistors and had the ability to remember its current state until it was reset, so in effect it was a storage device. In fact, Flip-Flops were the basis of the memory chips to come. A J-K Flip Flop logic circuit can be seen to the right. The J-K Flip Flop is constructed with four NAND logic gates. The J and K inputs labels were selected by the J-K Flip Flops inventor, Jack Kilby. Kilby was also one of the inventors of the integrated circuit.