System 360 Model 91

At one time the late 1960's, the 360 Model 91 was the most powerful computer in the world. There were numerous technical advances embodied in this machine, including instruction pipelining. However, it was very expensive. List price for the CPU alone was $6 million (that translates to $35 million in 2009). Only 15 were built and only 11 were shipped outside IBM. (Ref, IBM's 360 and Early 370 Systems, Emerson Pugh, et al, p.395.)

Here are a few pictures. The Gallery "machine shop" fabricated a new metal cart (complete with surplus mainframe casters), similar to the original but without any electronics inside.

The main processor technology used in the 91 was different from most other System 360 Systems. It needed to be faster. Originally it was called ACPX, but was quickly renamed ASLT, for Advanced Solid Technology (SLT was used in most other 360 systems and peripherals). The Gallery was very fortunate to find a display of ACPX technology (prior to renaming it ASLT) showing various stages of production. Here are a few pictures of the display, which is encased in heavy plastic.