IBM 650

The IBM 650 was IBM's first commercial business computer, a 2-address, bi-quinary coded decimal computer, with memory on a rotating drum, introduced in 1954. It was specifically designed for users of existing IBM unit record equipment upgrading from Calculating Punches (e.g., IBM 604) to computers.

The 650 system consisted of three cabinets:

• Console Unit
• Power Unit
• Card Reader/Punch Unit (Type 533)

The rotating drum memory provided 2000 10-digit words of memory, but was slow as a word could not be accessed until it passed under the read/write heads (avg. access time 2.5mS). An optional Magnetic Core unit providing 60 10-digit words, was introduced later to provide a little fast memory (access time 96uS).

External Links

• IBM Archives: Workhorse of Modern Industry: The IBM 650