IBM Hexadecimal Floating Point - Cleve Moler on Mathematics and Computing
 

<div class="content">Our technical support group recently received a request for a tool that would convert IBM System/360 hexadecimal floating point numbers to the IEEE-754 format. I am probably the only one left at MathWorks that actually used IBM mainframe computers. I thought we had seen the last of hexadecimal arithmetic years ago. But, it turns out that the hexadecimal floating point format is alive and well.

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[LIST][*][URL="https://www.labfans.com/bbs/#927291b6-bb83-4c85-937c-8f20844b3c74"]IBM System/360[/URL][*][URL="https://www.labfans.com/bbs/#43cbbb43-f2f5-4415-99df-f6a6c114c912"]Formats[/URL][*][URL="https://www.labfans.com/bbs/#5d482994-2d0d-42fa-86e2-c98bc728ebbe"]Data[/URL][*][URL="https://www.labfans.com/bbs/#099df223-ed1e-405e-917f-0cccd1d54a26"]Hex_ieee[/URL][*][URL="https://www.labfans.com/bbs/#126c1d80-75f5-4879-841f-de925f083fc1"]ieee2ibm[/URL][*][URL="https://www.labfans.com/bbs/#88d3bc9c-b626-4578-872e-b95f02057e43"]ibm2ieee[/URL][*][URL="https://www.labfans.com/bbs/#64f8c2ec-011c-40a2-a2f3-a2926ee929ac"]Examples[/URL][*][URL="https://www.labfans.com/bbs/#41ed0fce-64bf-4471-b2c3-e22645d184f5"]Comparison[/URL][*][URL="https://www.labfans.com/bbs/#9e4ce83f-58b7-498d-b480-9f17c5c1f6e0"]Software[/URL][/LIST][B]IBM System/360[/B]

The System/360 is a family of mainframe computers that IBM introduced in 1965 and that dominated the computer industry until PCs came along twenty years later. They range in size from desk-sized to systems that fill a large room.

Here is a photo of a mid-sized model.

[IMG]https://blogs.mathworks.com/cleve/files/ibm-360-60.png[/IMG]

[I]System/360, Model 60.[/I] [I]Photo from Ken Shirrif's blog, IBM 360/System Summary[/I].

The System/360 architecture is byte-oriented, so it can handle business data processing as well as scientific and engineering computation. This leads to base-16, rather than base-2 or base-10, floating point arithmetic.

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