The IBM System/360 was a groundbreaking family of mainframe computers announced on April 7, 1964. System/360 was an extremely risky "bet-the-company" project for IBM, costing over $5 billion, but the System/360 ended up as a huge success, setting the direction of the computer industry for decades.
Branch entry to i-fetch microinstruction.
The S/360 architecture was so successful that it is still supported by IBM's latest mainframes, almost 60 years later. Ken Shirriff is developing a microcode-level simulator for the IBM System/360 Model 50; this blog post provides background to understand the Model 50 and the simulator. post 
simulator
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With each step the simulator displays the microcode instruction as it would appear in a listing. Click ⓘ for pop-up instruction explanation.
