IBM Advanced Computer Systems project: Difference between revisions

Revision as of 11:56, 26 April 2024

Revision as of 12:03, 26 April 2024

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In December 1967, Amdahl began calling people within IBM to tell them about the new design. This proved interesting to management, who arranged a complete project review in March 1968 under the leadership of Carl Conti from IBM Poughkeepsie. Amdahl presented performance estimates based on hand-calculated cycle counts. Lynn Conway would later conclude these numbers were unlikely to be anything close to correct, but the team accepted them in any event.{{sfn|Conway|2011}} Likewise, Amdahl's claim of an 8 nanosecond cycle was accepted although Mark Smotherman suggests it is not realistic. Conti concluded that on integer benchmarks, the AEC/360 would be up to five times as fast as the ASC-1, it would be up to 2.5 times slower on floating-point, and the complex branching system of ASC seemed to offer 10 to 20% at best and could be adapted to the AEC if desired. But a key point was that if the ASC system was so reliant on the compilers for its performance, moving that code to some other machine could result in far different outcomes and that could be considered a disadvantage.{{sfn|Smotherman|Sussenguth|Robelen|2016|p=67}}

The most serious blow to the ASC was the continued success of the S/360. AroundIn thisJanuary time1968, [[NASA]] had taken delivery of a 360 Model 95, which IBM described as "the fastest, most powerful computer now in user operation."{{sfn|Smotherman|Sussenguth|Robelen|2016|p=67}} A finalAnother problem was comments bythat Max Paley supportingpublically supported Amdahl's concept. In the aftermath of the review, most of the upper management team left, Amdahl was placed in command, and the AEC/360 became the ACS-360. One major change was to introduce [[register renaming]] as part of the out-of-order system.{{sfn|Smotherman|Sussenguth|Robelen|2016|p=67}}

===Cancellation===