System software:Running applications within the Mac/GEM environments
Running applications within the Mac/GEM environments
As indicated above, to run an application from the desktop you simply click on the icon that represents it. On the PC, most software that you run from GEM Desktop will take over the screen, and will not use any of the mouse, icon, scroll bars, and pop-down menu features that GEM pro vides. You will not in fact be aware that GEM is lying dormant in the background until you leave the application, when you will be returned to the desktop. However, some applications are specially written to run within the GEM environment, and these make full use of GEM's facilities.
On the Atari ST, almost all software is designed to use GEM's facilities, and one of the main features of the Apple Mac is the fact that all applications adopt the mouse-and icon way of working.
Windows
Early versions of Windows were much inferior to the Mac/GEM environment, and little application software was written to take advantage of this environment. With version 3, released in 1990, Windows has become a fully-fledged graphical user interface. Its desktop somewhat resembles the Mac/GEM Desktop, with scroll bars, pull-down menus, icons, dialogue boxes, etc. The virtually identical product for the PS/2, Presentation Manager, appeared a couple of years earlier.
Although it arrived late on the scene, Windows 3 is much more powerful than GEM, as it overcomes the two main limitations of (the current version of) the PC's operating
system, DOS:
• It breaks the 640K memory barrier, allowing Windows applications to use up to 32 Mb.
• It provides multitasking facilities, i.e. it can run several applications at the same time, each within a different window. This multitasking capability is very potent, for it allows you to switch instantly from one task to another, to copy data rapidly from one to another, and to carry out one job while another is being processed in the background.
Note that these facilities are only fully available on PCs using the 80386 processor and above. PCs with lower specifications can use only some of the power of Windows. In addition, Windows may run so slowly on cheaper machines that it loses its appeal. (Alternative operating environments are available for low-cost PCs- see later.)
Windows also offers a number of other powerful features, including Dynamic Data Exchange (DDE). This allows data to be copied from one Windows application to another, and the link that is thus created between the two applications kept 'live'. This means that if the data is changed in one application, these changes are automatically updated in the other.
At the time of writing, Windows v .3 has only recently appeared. However, it is growing rapidly in popularity, a number of applications have appeared which make use of its features, and a very large number of Windows applications are in the pipeline. (As with GEM, non-Windows applications take over the screen, leaving Windows in the background.) There seems little doubt that by the mid-1990s it will be the main way of working on PCs.
Presentation Manager, in contrast, has relatively few applications written for it, the result being that it has so far (i.e. by 1990) had hardly any impact on the world of microcomputing. This may change in the future, however.
As people get used to Windows on PCs they may well migrate to the more powerful PS/2 hardware platform running the almost identical PM.
Other environments for PCs
You can have multitasking, access to large amounts of memory, and a mouse-and-windows environment, without resorting to running Windows on a high-specification PC. One environment that will give you all these things and yet which will run on the lowliest 8086 machine is Desq View, from Quarterdeck.
DesqView is not a graphical user interface, so it does not use icons. It is character-based. The term COW (Character Oriented Windows) is applied to software that is character based but uses the mouse and windows. Like GUI environ ments, COW software includes devices such as pull-down menus and dialogue boxes from which you can make selections using the mouse. Its advantage over GUI software is the speed at which it runs, even on low-spec PCs.
Grand View (Figure 5.5), the package I am using for writing this book, is COW software, and it's one of the fastest packages I've ever used. For ordinary tasks like writing text or keeping records there is little point in graphical user interface, as no graphics are involved. (If I were desktop publishing this book, however, I would want a GUI.) Another popular COW package is PC Tools (version 5 and above), from Central Point Software.
Utilities
The third category of system software is utilities. These enable you to extend the power of the operating system, by:
• Carrying out tasks which are beyond the capabilities of the operating system.
• Carrying out operating system tasks in a more efficient and easier way.
Some utilities are designed to carry out one job only, such as restoring files that have been deleted in error. Others provide a computer housekeeping environment, enabling you to carry out housekeeping tasks as easily as in GEM or Windows, and from which you can run applications. The latter may include facilities which are lacking in GEM and Windows, such as options to hide files so that they cannot be listed, to protect files so that they cannot be altered or deleted, and so on.
However, unlike the Mac/GEM or Windows environments,
Figure 5.6 Power Menu, an example of a front-end to DOS
you cannot run applications from within this type of software; you must run them from the operating system itself. All that this software does is provide an easy access to the operating system's facilities, together with a menu of some kind that enables you to run applications from within the operating system. For this reason they are called front ends (to the operating system) rather than environments.
Popular front-ends to DOS are Power Menu (Figure 5.6), PC Tools, Qdos, and Xtree.
Comments
Post a Comment