IBM Advanced Computer Systems project: Difference between revisions

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In late 1964, Amdahl had taken a teaching position at [[Stanford University]]. In January 1965 he was named an [[IBM Fellow]] for his work on the [[System/360]], which was introduced shortly before he left the company. Even after less than a year, the 360 was one of the most successful computers in history with an order book many times longer than predicted. Around the same time, IBM decided to centralize development of the ASC at a new ___location in [[Mountain View, California]]. As a Fellow, Amdahl was entitled to work at any IBM facility of his choosing, and having heard of the move, asked to join ASC. After a short time, in August 1965 he argued that the machine should be based on the System/360 instruction set, which caused ASC management to ostracize him.<ref name=interview>{{cite journal |journal= IEEE Design and Test of Computers |date=April 1997 |title=Interview with Gene Amdahl}}</ref>

Over the next two years, the issue of 360 compatibility was argued back and forth. In January 1967, [[Ralph L. Palmer]] asked [[John Backus]], [[Robert Creasy]], and Harwood Kolsky to review the project. Kolsky concluded that thisthe 360-compatible version would be too difficult, and pointed out that the ASC was aimed at the [[CDC 6600]] market, not the 360's, so if the customer was interested in compatibility, 6600 compatibility would seem more useful. The next month, Amdahl once again argued for 360 compatibility for marketing reasons, and then in December he met personally with Kolsky to demonstrate how this might work. The previous month, in November 1967, Herb Schorr had presented a timeline for the first delivery in 1971 with a development budget for software on the order of $15 million. Amdahl argued that a fast 360 platform would offer much of the performance yet eliminate the need to develop a new [[operating system]] and all of the associated programming languages and support, and that that money would be better spent on improving OS/360 in general, which would improve the entire line.<ref name="smotherman"/>

As a result of this ongoing argument, Amdahl was ostracized within the team. As further punishment, they assigned John Earle to work for him. Earle was a brilliant circuit designer, but his interactions with other team members led to him being forced out as well. Earle and Amdahl then designed a new concept using the ASC's circuit design to produce a high-end 360. The two quickly proved that one could use the ASC circuit designs to build a 360 that was slightly slower than the ASC-1, but cost perhaps 75% as much to build, with only 90,000 gates instead of 270,000 (a gate requires about five transistors using the ECL logic of the era).

In December 1967, Amdahl began calling people within IBM to tell them about the new design, which eventually led to a management overview and "shoot out" between the two approaches. Lynn Conway would later conclude these numbers were unlikely to be anything close to correct, but management accepted them in any event.<ref>{{cite web |url=http://ai.eecs.umich.edu/people/conway/Memoirs/ACS/Lynn_Conway_ACS_Reminiscences.pdf |title=IBM-ACS: Reminiscences and Lessons Learned From a 1960’s Supercomputer Project |first=Lynn |last=Conway |date=2011}}</ref> In May 1968, the decision was made to go with Amdahl's approach, and this resulted in the name change from ''ACS-1'' to ''ACS-360''. At its peak, the ACS-360 project involved over 200 engineers and staff.<ref name="smotherman"/>

The ACS-360 project was canceled in May 1969; Amdahl claims this was primarily due to it upsetting IBM's carefully planned pricing structure. The company as a whole had an understanding that machines above a certain performance level would always lose money, and that introducing a machine that was so fast would require it to be priced in a way that would force their other machines to be reduced in price.<ref name=interview/>