Editing IBM Future Systems project (section)

=== Project end ===
The FS project was terminated in 1975. The reasons given for terminating the project depend on the person asked, each of whom puts forward the issues related to the domain with which they were familiar. In reality, the success of the project was dependent on a large number of breakthroughs in all areas from circuit design and manufacturing to marketing and maintenance. Although each single issue, taken in isolation, might have been resolved, the probability that they could all be resolved in time and in mutually compatible ways was practically zero.

One symptom was the poor performance of its largest implementation, but the project was also marred by protracted internal arguments about various technical aspects, including internal IBM debates about the merits of RISC vs. CISC designs.  The complexity of the instruction set was another obstacle; it was considered "incomprehensible" by IBM's own engineers and there were strong indications that the system wide single-level store could not be backed up in part,{{clarify|reason=What does "could not be backed up in part" mean?|date=July 2020}} foretelling the IBM AS/400's partitioning of the System/38's single-level store.<ref>{{cite book|title=AS/400 Disk Storage Topics and Tools|id=SG24-5693-00|url=http://www.redbooks.ibm.com/abstracts/sg245693.html?Open|date=April 2000|publisher=IBM}}</ref>{{clarify|reason=Partitioning in the LPAR sense, or in some other sense?|date=July 2020}} Moreover, simulations showed that the execution of native FS instructions on the high-end machine was slower than the [[System/370]] [[emulator]] on the same machine.<ref>{{cite web|url=http://www.jfsowa.com/computer/memo125.htm|title=Memo 125|first=John|last=Sowa|date=November 27, 1974}}</ref>

The FS project was finally terminated when IBM realized that customer acceptance would be much more limited than originally predicted because there was no reasonable application migration path for 360 architecture customers. In order to leave maximum freedom to design a truly revolutionary system, ease of application migration was not one of the primary design goals for the FS project, but was to be addressed by software migration aids taking the new architecture as a given. In the end, it appeared that the cost of migrating the mass of user investments in COBOL and [[assembly language]] based applications to FS was in many cases likely to be greater than the cost of acquiring a new system.