Joe's OS/2 Tips - Number 2

Well I am back again with another few pages of notes on OS/2 ver 2.0. This time I will discuss some of the many DOS_SETTINGS that can be quite useful in changing the performance of your system. Many of these setting are self explanatory, for anyone who's got a general knowledge of the IBM PC class of computers (specifically 286, 386s, 486s), and to others, seem to be alien terminology. In this issue I'll cover the 'special options' that tie DOS to OS/2.


 * DOS_BACKGROUND_EXECUTION
 * DOS_VERSION
 * IDLE_SECONDS
 * IDLE_SENSITIVITY
 * MOUSE_EXCLUSIVE_ACCESS
 * VIDEO_RETRACE_EMULATION
 * VIDEO_SWITCH_NOTIFICATION
 * VIDEO_WINDOW_REFRESH

Many of these are confusing, to people who have never had any experience in Multi-tasking. Desqview and Windows have some settings like these, so if you've upgraded from one of these environments, some of the following should be already mastered.

DOS_BACKGROUND_EXECUTION
Since OS/2 attempts to allow all applications to run, many users are quite happy to have their DOS database perform a calculation, while happily writing the latest e-mail message to someone (or in a lot of cases, studying how to use a mouse, while performing difficult drop n' drag techniques with solitaire :-) (this is one of many similes, to denote sarcasm, found in e-mail messages)).

Thus, for most of your applications you'd want OS/2 to keep executing the application, but what about your latest DOS game? I know myself, that many of these newer creations are nearly impossible to beat when your playing them, so don't give them the advantage of running, while your not there.

On the serious side, I myself when writing programs (or stuff like this), find the ability to switch from window to window great, thus I often have this setting to OFF, so that my whole system is freed from running these apps, thus the system is faster. Why have a word processor sitting there chewing up system resources, when I am in another window doing real work? This way my whole system is fast and efficient. Then again, I don't run much DOS stuff these days.

DOS_VERSION
People familiar with DOS 5's SETVER would be well versed in what it allows you to do. Basically DOS_VERSION allows your DOS program to lie to the system about what version of DOS it likes, and get away with it. This is a useful command, where some of the popular DOS programs are written for a specific DOS version, (one way to keep software companies in the Black) which won't run under OS/2's emulated DOS 5.0.

I won't go into details about this command, since OS/2's on line help is enough to solve your problems with this DOS_SETTING.

IDLE_SECONDS / IDLE_SENSITIVITY
Both these options allow you to really tune your particular application, for use under OS/2. Simply with these settings, OS/2 will Dynamically look at your DOS application, for a particular period and see what the program requires (in time) of the CPU.

For instance, a graphics intensive program (like Wing Commander 2), will require a rather high IDLE_SENSITIVITY, and at least 1 for IDLE_SECONDS, for a good response, as expected under vanilla DOS. Whereas a word processor only requires minimal attention. In particular, experience with Word Perfect V5.1 (for DOS), shows that a IDLE_SENSITIVITY of around 5 will make you system fly, whereas a higher system will severely limit your system's speed. Apparently Word Perfect was programmed to heavily scan the keyboard for a key press, this is an example of what a Bad DOS application can do. I could never see a human typist, capable of out typing a computer, have you?

IDLE_SECONDS, is a special command which tells OS/2 to wait for a specified time, before reducing that applications time with the processor. Since not all DOS programs rely on keyboard activity to run, the newer graphics intensive programs (or in other words, games), maybe lacking in punch, so 'fiddle' around with this setting, to get a better performance (also the following system settings are important, read on)

MOUSE_EXCLUSIVE_ACCESS
Well how many articles have you read about OS/2's inability to handle Mouse operated DOS programs, in a Window, or the dreaded Double mouse pointer problem? Well with this option activated the window gains sole writes to the mouse (and elimiated the double mouse pointer), and only a CTRL-ESC (Task/Window-List) will give the mouse back, to the whole system.

So the next time you read this, send a note of correction to the reviewer, who probably has never really played with the system, or worse he uses widows (spelling mistake is intentional!).

VIDEO_RETRACE_EMULATION
Well here's a nice OS/2 only weridie. It's a very intelligent solution to many of the DOS programs, which wait for a whole screen to be drawn before continuing, which not only slows your system, but is entirely useless in text mode applications. This option will tell the DOS program that the screen update, it requested, was performed, before it was completed, thus enabling the program to continue on. I used this on PC-FILE to increase the speed of the program, while updating stock lists.

But like with most things, this option must be deactivated, once your into special programs, like Games, are executed, since they rely heavily on the user's eyes to see the screen ;-). Not much use in Keen 4, when your screen disappears, and reappears, with a sound, from the sound blaster, informing you, of your sudden demise.

In some cases, some graphics programs perform better with this option ON, so if your working on DTP stuff, I'd say try it, sice you can always turn this setting off with your mouse, later.

VIDEO_SWITCH_NOTIFICATION
With OS/2, you have the ability to switch from a full screen to a window and back again (in any order or number of times). Some of the DOS programs will 'trash' the screen because they can't handle the change between the two(or your application appears to freeze after the swap). The solution is, to switch back again with ALT-HOME (or with the mouse) and turn ON this switch, and try again.

I've found that some of Turbo Pascal applications will casue this problem, especially if your using the new version (ver 6.0) that utilize Objects for Turbo Vision.

VIDEO_WINDOW_REFRESH
I like this option, for my normal dos windows, since I can tell OS/2 the frequency of screen redraws, performed by a DOS program. This is a great option if you just want to use a text based app, because it greatly increases the speed. For example a large database search, under some text-based DBs, will be dramatically increased, if you set the setting to 10 or so, so that instead of the system worrying about the 'in-between' actions on the screen, it's working as hard as possible on the result (which is, after all, what we want).

THE FUTURE
Well that's all folks, but in the future editions, I'll start to get a few screen shoots in, of various topics relating to what I am writing about. Also coming up, will be a review on IBM's WorkSet tools, which I should be receiving sometime before next edition. This means that, you'll also be getting some source code to play with, as I am learning the in's and out's of programming under OS/2 ver 2.0

Any ideas or suggestions send them via Worldnet to me at 61:6700/1 or ring my system on +61-7-800-3521.

Cuya all Next Time, Joseph Mckinnon.