Ken Shirriff's blog

Computer history, restoring vintage computers, IC reverse engineering, and whatever

Showing posts with label electronics. Show all posts

Showing posts with label electronics. Show all posts

Understanding silicon circuits: inside the ubiquitous 741 op amp

The 741 op amp is one of the most famous and popular ICs [1] with hundreds of millions sold since its invention in 1968 by famous IC des...

Qui-binary arithmetic: how a 1960s IBM mainframe does math

The IBM 1401 computer uses an unusual technique called qui-binary arithmetic to perform arithmetic. In the early 1960s, the IBM 1401 wa...

Fixing the core memory in a vintage IBM 1401 mainframe

I recently had the chance to help fix one of the vintage IBM 1401 computer systems at the Computer History Museum when its core memory sta...

Examining the core memory module inside a vintage IBM 1401 mainframe

The IBM 1401 mainframe computer was announced in 1959 and by the mid-1960s had become the best-selling computer , extremely popular with me...

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