IBM Monolithic Systems Technology

The IBM System/360 mainframe development which started in 1961 was the biggest product development in corporate history. Costing $5B at the time ($44B today), it was a huge gamble, but it paid off handsomely for IBM. They dominated the market for the remainder of the mainframe computer era.

There were several big innovations which created its success, including, upwards/downwards software compatibility across the range, standard interface for many different peripherals, emulation of other platform developed software, adoption of the 8-bit byte and Solid Logic Technology.

Seen in close up, SLT was a ceramic substrate technology with printed resistors and mounted transistors, creating Resistor Transistor Logic (RTL) blocks. The resistors were trimmed before the lid was put on the modules.

IBM gambled in large part because they were facing increasing stiff competition. One of their competitors launched a product with early logic integrated circuits. IBM had considered this but felt the technology was too immature. They were right as the competitor's computer had many yield and cost issues and it failed.

By the time the System/370 was launched, IBM had adopted logic ICs (now called Monolothic Systems Technology), but they still packaged them in the same ceramic substrate package format.

IBM during the 60s was the world's largest producer of semiconductors and also used external companies like TI and Raytheon to produce discrete packaged transistors for their products.

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