Robert Creasy
Robert Jay Creasy | |
|---|---|
| Born | Template:Birth date Honesdale, Pennsylvania, U.S. |
| Died | August 11, 2005 (aged 65) |
| Occupation | Computer scientist |
| Known for | Principal developer of IBM CP-40 virtualization hypervisor |
Robert Jay Creasy (November 15, 1939 – August 11, 2005) served as the principal developer of the pioneering full virtualization hypervisor, known as the IBM CP-40, which laid the foundation for IBM's widely adopted mainframe VM operating systems.
Biography
Creasy was born in Honesdale, Pennsylvania, and completed his studies at MIT in 1961, the same year he wed Rosalind Reeves. Prior to his tenure at IBM, he contributed to the development of the CTSS and Project MAC. At IBM, he took charge of a timesharing system initiative at the Cambridge Scientific Center. In 1965, he and his wife relocated to California. After retiring from IBM’s Palo Alto Scientific Center in 1993, Creasy passed away in 2005, leaving behind his family.
Origins of VM
Following IBM's loss of the Project MAC contract in 1964 and its commitment to TSS, Norm Rasmussen from IBM’s Cambridge Scientific Center launched a new timesharing effort under Creasy’s leadership, culminating in the creation of the CP-40 system.
Late in 1964, Creasy designed CP-40 as an innovative operating system that introduced virtual memory alongside virtual machines. This system utilized the System/360 Principles of Operations manual as an interface to the Control Program, allowing each user to run a fully functional System/360 virtual machine. This design required only minimal modifications to hardware and software.
To support development within this environment, Creasy and his team created CMS (initially called “Cambridge Monitor System”), drawing inspiration from CTSS’s user interface, which operated inside virtual machines.
The combination of CP-40 and CMS evolved into CP/CMS, which IBM made available to customers in 1967. An updated version was released in 1972 as IBM's VM/370, representing a major advancement in virtualization technology for enterprise computing.
References
- Creasy, R.J. "The origin of the VM/370 time-sharing system." IBM Journal of Research & Development, vol. 25, no. 5, Sept. 1981, pp. 483–490. IBM.
- Varian, Melinda. "VM and the VM community, past present, and future." SHARE 89 Sessions 9059-9061, 1997.