Originally set for release mid-1996 Mac OS 8, code-named Copland has had a number of set backs and now isn’t due until mid-1997, at least. Mac OS 8 is designed to improve the performance of current Macintosh applications, and will drive a new generation of multimedia and productivity applications. Mac OS 8 will be optimized to take advantage of the power of PowerPC RISC processors, incorporate advanced multitasking capabilities, and integrate memory protection capabilities to improve the stability of the computing environment, something which is long overdue…     In terms of performance Mac OS 8 will gain significantly by being almost entirely written in native code for PowerPC processors. In addition the new technologies in Mac OS 8 include improved algorithms that run more efficiently. To get the increased performance, however, applications must make use of these new technologies. At the present time Mac OS 8 will require a PowerPC processor to run although there are rumours that Apple are working on a 68K version for release at a later date.   Unlike previous versions of the Mac OS, Copland will let users choose from a variety of desktop styles that affect the look and feel, and in some cases even the sound of the Mac's user interface. Styles include the standard 3D look, a kids type style with animated flip-down menus accompanied by amusing sounds, an At Ease style with one-click buttons and a hi-tech look. In addition, all windows in Copland will contain a small icon to the left of the window's name in the title bar. Users can directly manipulate the item the window represents by dragging the item's title-bar icon to a destination elsewhere on the screen. If the destination is on the same storage device as the item, this action moves the item; if it is on a different storage device, this action copies the item. The Copland user experience includes several new interface elements to make it easier for users to manipulate items directly. In addition to the title-bar icon, mentioned earlier, Copland adds the spring-loaded folder, which causes a folder to open when an item is dragged over it. By dragging an item over successive folder icons, a user can drop the item into a deeply embedded folder with one movement. When the user finally drops the item into a window, all of the intermediate windows opened during the extended drag operation close automatically, thus reducing screen clutter. Another interface element is called the pop-up window; it allows windows to remain open without cluttering up the desktop. Under Copland, users can drag a window to the bottom of the screen, where its title bar is shortened to allow multiple title bars to show. When the user drags an item onto a shortened title bar, the full window displays itself, and the user can drop the item into the window. When the user activates another window, the pop-up window minimizes itself again at the bottom of the screen.   At Copland's core lies the microkernel, the behind-the-scenes arbitrator of the complex machinations that make Copland such a significant advance over System 7.5. The microkernel will be responsible for managing memory (including virtual memory), allocating CPU time to all software, applications running in the compatibility box, preemptively multitasked server tasks, and the OS itself, and several other low-level activities, such as interprocess communication. As its name suggests, the microkernel is only a tiny bit of Copland's code, but its performance and reliability will be critical to Copland's success and considering the resources that Apple has dedicated to perfecting it, we consider the probability of that success to be good. Copland will have a vastly improved virtual-memory system, resulting in better performance of the code-fragment manager, the part of the OS that's responsible for loading into memory only those parts of an application that are actually needed at any given moment. Applications will load faster and require less RAM. Applications will also be able to spin off multiple server tasks into their own protected memory spaces. There they will be able to run unattended in the background, safe from most system crashes. However, only those processes that do not require user-interface activity will be able to become server tasks.   In the current Mac OS, applications compete for CPU resources, with the result that some hog processing power while others starve. Copland will reduce this anarchy by using a technique called pre-emptive multitasking, in which the OS takes over resource scheduling, but only for server tasks and some OS functions. The result will be faster, more responsive performance of file and network I/O and greatly improved background-task performance.   Even though Copland is fundamentally different from the current Mac OS, current applications will run without modification in what Apple engineers call the compatibility box. One important benefit: If an application crashes, only the compatibility box will need to be rebooted - most core system functions, extensions, and server tasks should remain unaffected, resulting in a greatly reduced rebooting time.