Before revision: No other version of the operating system was released externally, but internally the development of the desktop and window management continued, with the addition of a cooperative multitasking system, invented by Neil Raine, which used the memory management hardware to swap-out one task, and bring in another between call-and-return from the WIMP-Poll call that applications were obliged to make to get messages under the desktop.
After revision: No other version of the operating system was released externally, but internally the development of the desktop and window management continued, with the addition of a cooperative multitasking system, implemented by Neil Raine, which used the memory management hardware to swap-out one task, and bring in another between call-and-return from the Wimp_Poll call that applications were obliged to make to get messages under the desktop.