Part 3 - The RISC OS Task Manager

One very useful program in RISC OS is the Task Manager. This allows users to view and manage how much memory is allocated to various system functions as well as user applications.

The Task Manager icon is the rightmost icon on the Iconbar and in RISC OS 4 is represented by the RISC OS 4 cube logo. In RISC OS 3 this was represented by an Acorn logo (two different styles) and in RISC OS 2, this was an Archimedes logo.

Clicking the Task Manager icon with Select, results in the task display window being opened.

At the top of the Task Display window is the list of tasks which are running. These are typically user applications such as text editors, drawing programs, web browsers etc. Each entry in the task list has a coloured bar next to it representing the memory usage of the task. Next to the bar is the actual memory usage in figures.

Also in the top part of the window are the Now and Next bars, which show how much memory is currently free and how much would be allocated to the next task which the user runs. All free memory is split between the now and next bars, but may be adjusted by the user so that operations can use more memory. Reducing the next bar has the result of increasing the now bar by the same amount and vice versa.

If the user were to start a file copy operation for example, the copy operation, would be allocated the amount of memory indicated by the next bar. Moving the bars with a mouse drag operation allows the user to adjust these settings.

At the very bottom of the Task display window is the Dynamic Areas section (if present), just above this is a total of all the available memory in the system. The task display window breaks this total down into sections to show how the memory is allocated to different tasks.

Mid way down the window is a list of module tasks which are using Relocatable Module Area (RMA) space. These are not full applications but modules which applications can load into memory and use. Some modules are delivered with the operating system and some are written by third parties to allow reuse and / or extension of the operating system itself. Modules can be thought of as bits of code which provide services to other programs. The ADFS Filer is an example of a module which is supplied with the operating system.

A relatively new edition to the Task Manager are Dynamic areas of memory, which applications can use for their working memory. These areas, as their name suggests, can grow and shrink as required. Dynamic allocation of memory is also a feature which the (RMA) also provides (from RISC OS 2 onwards), but the RMA can become fragmented with holes of free space, whereas the Dynamic Areas do not.

Many popular applications were updated to make use of Dynamic Areas when the feature became available - In RISC OS 3.5 (I think).

RISC OS Ltd. even updated Acorn's original Paint and Draw programs to use Dynamic Areas, although these were released on a no-support basis.

Adjusting system performance

RISC OS is a very dynamic and flexible OS. It allows users to adjust memory allocation whilst the system is running. You can even change screen mode to free up memory for a large task and the system will then allow that memory to be used. You can at any time allocate memory to the font system or a RAM disc.

Filer operations

Some filer operations can be more efficiently executed if they are given more memory. Normally such operations would be allocated the amount of RAM which is set as Next in the Task Manager, but the user can actually increase this after the operation has started, which means less small disc accesses but fewer longer spells of reading and writing.

Font cache & RAM Discs

Depending on the settings which have been configured for the Font Manager, allocating extra memory to the Font cache can improve system performance when screen redrawing is required.

Both RAM discs and Font cache settings can be configured for next boot up, but can also be modified once the system is running. As an exercise, try creating a RAM Disc by dragging out a red bar next to the RAM Disc entry in the Task Manager, this will result instantly in a RAM Disc icon appearing on the Iconbar ready for use.

Killing tasks & Modules

Many tasks and modules can be quit from the Task Manager, using the menu obtained by clicking the middle button over a particular task or module. Rather than using the quit option from the Iconbar menu of a task, using the Task Manager, sends a message to the task or module to quit, this enables you to kill tasks which don't have an icon or those which for some reason do not allow quit from the Iconbar.

Other Facilities of the Task Manager

The Task Manager also provides facilities for creating task windows, jumping out to a command line, giving information about the version number of RISC OS which is running and shutting down your RISC OS computer. Finally, the Task Manager in most versions of RISC OS hides a secret (known as an Easter egg) - In RISC OS 3.10 you could click out the letters "T" "E" "A" "M" on the program information window for the Task Manager with the middle mouse button and you would see a scrolling message about the people who worked on it. RISC OS 4 has a similar (Although much shorter) message if you triple click somewhere in the same window.

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