Since, as we stated above, ESL's "PRGMAX" setting reserves an address range of memory for ESL's use during program execution.  It follows that other applications running at the same time will not have access to that address range of memory.  However, as current 32bit Processor technology has a total virtual address range of 4 Giga-bytes, it is highly unlikely that the reserving of the address range will be an issue. Although the address range can be considered as virtually limitless, the Operating System does restrict the amount of Virtual Memory available. Whilst the Virtual Memory can be manually altered, it is not recommended to have a Virtual Memory setting more than double to physical random access memory (RAM), otherwise the machine’s performance will be significantly degraded. You should ensure that all the Virtual Memory requirements of the applications, including the PRGMAX setting for each ESL application, plus the Operating Systems comfortably fit into the Virtual Memory that has been allocated. There a number of tools supplied with the Operating System, for example “PERFMON” and “Task Manager”, which can help determine to existing memory requirement.