Ultra high-speed logic LSIs, used in the FACOM M-200 and FACOM M-190. At the start of the 1970s, the field of memory devices saw the emergence of semiconductor memory (IC memory) as a replacement for conventional core memory, and the shift to LSIs in this field began. However, attempts to raise the speed of LSIs ended up being an ongoing battle against heat generation. Since their efficiency would decline significantly with an increase of heat, the first step in practical implementation was finding a way to suppress heat from being generated. Mounting five cooling fins on these LSI devices proved to be an effective method of heat dissipation, and paved the way for the implementation of high-speed LSIs.