John Iliffe (computer designer)
His design included an early instance of dynamic memory allocation and management, enabling programs to acquire storage on demand and automatically recover it when it was no longer accessible.The Basic Language Machine (BLM),[5] constructed and evaluated in the research department of International Computers Limited (ICL) between 1963 and 1968[11] was the first general-purpose system to break completely with the Von Neumann architecture.Iliffe took the engineering view that it should be possible to offer a way, based on the memory management techniques already demonstrated in the Rice R1 to ensure the integrity of concurrent programs without resorting to relatively expensive mechanisms involving the frequent swapping of process state vectors seen in most other systems.The Rice R1 and the BLM were examples of descriptor-based computer architectures that emerged in the 1960s[6] aimed both at the efficient protection of concurrently-executing programs and the reliable implementation of high-level languages.In parallel with construction of the BLM a separate evaluation team assessed it in terms of (1) program efficiency (2) operating characteristics (3) coding and debugging costs and (4) system overheads.Levy[6] discusses the wider impact of descriptor-based computer architectures with reference to both the Burroughs B5000 and the BLM (p. 38) "... whether or not they were long-lived, these machines demonstrated the feasibility of using descriptors and segmentation to greatly increase programming flexibility for the user, the compilers, and the operating system".