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1948 IBM 604 Pluggable Unit and Advertisement



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This is called an IBM Pluggable Unit using a vacuum tube and supporting electronics for computing machines of the late 1948s.  Included is original IBM advertisement “Fingers You Can Count On” (size 11” x 8”).  This was a new and revolutionary idea of the era.  In 1948 IBM announced the 604 Calculating Punch Machine that used a revolutionary internal circuit called a “Pluggable Unit” for NOT, AND comparison logic and mathematical calculations that could quickly be removed if it failed and new replacement inserted.  Prior machines often times failed and would take many hours, days and even weeks to repair.  The IBM 604 and later machines could have as many as 1,400+ tubes and it was important to diagnose point of failure and easily swap out failed Pluggable Unit with new Unit.  IBM tube is marked 5965 and top handle CF-1 with three levels of supporting electronics (Tube, and 2 levels of electronics).  Size 5” in length.   These 50+ years old Pluggable Units are rarely found as most are now in museums.  This is a treasure of computing history and belongs with a serious collector or computer museum.

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