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Text File | 1985-09-16 | 14.1 KB | 395 lines

Silence Version 2.0 Copywrite (c) 1985 by Carl Burtner This Program Is In The Public Domain. Users are encouraged to make as many copies as they like and to distribute them to whomever they choose. Under No Circumstances Is This Program To Be Sold. If you have problems, questions, suggestions, or desire a copy of this programs assembler listing, please contact me. Carl Burtner 435 Brandon Road Rochester, N.Y. 14622 Silence Version 2.0 Silence is dedicated to keeping your PC quiet. Most program sounds will be eliminated entirely or reduced to a series of clicks. Some sound effects which use short duration tones or turn the PC's interrupts off may not be silenced. Compatibility Silence should be compatible with most programs and IBM-PC compatible computers. Silence 2.0 has some advanced options which can enhance its ability to silence some previously unsilenceable sounds. These options may not be compatible with all programs. Incompatibility generally makes itself evident by greatly slowing down the program. When in doubt, Silences default settings have never been observed to cause problems. Display Adapters To speed things up, Silence 2.0 uses direct writes to the screen buffer for displaying the function access screen and the copywrite notice. To do this, Silence does its best to determine the type of display adapter installed. It is possible that a non-standard adapter could fool Silence into making a wrong assumption. If this happens the display will most likely remain blank. To force Silence to ignore its determination and use either the color or mono display adapter enter the command "Sil2 c" for the color adapter or "Sil2 m" for the mono adapter. Installation Silence is a resident program. Once installed, Silence remains in the computers memory until it is turned off or rebooted. To install Silence just type the name of the program (Sil2) and hit the return key. Silence will initialize and display a function access screen which allows the setting of several options. If you don't wish to change any options either hit the escape key once or hit the return key several times to tab to the end of the screen. If you wish you can install Silence without being presented with the function access screen. To do this enter "Sil2 d" (the d stands for default) without the quotes. Silence's options may be changed at any time either by entering one of the commands described below or by entering Sil2 to use the function access screen. However, because Silence is a resident program it is possible that another resident program installed after Silence may make it impossible to change Silence's settings. If this should happen Silence will inform you. To correct the problem try -1- Silence Version 2.0 rebooting and installing Silence after any other resident program being used. Commands Silence 2.0 supports the same commands as Silence 1.0. These are: Sil2 on - Turns Silence on. Program sounds will no longer be heard. Error messages are returned if Silence has not been installed or if changing the setting is not possible. Sil2 off - Turns Silence off. Program sounds will now be heard. Error messages are returned if SILENCE has not been installed or if changing the setting is not possible. In addition, Silence 2.0 adds the following commands: Sil2 d - Installs Silence without displaying the function access screen. Sil2 c - Installs Silence and/or displays the function access screen assuming that the color display adapter is installed Sil2 m - Installs Silence and/or displays the function access screen assuming that the monochrome display adapter is installed. Only one command may be entered at a time. Theory of Operation System Clock The IBM PC has a system clock that "ticks" 18.2 times a second. Every time the clock ticks an interrupt is generated. The interrupt causes the computer to stop whatever it is doing and execute a short program stored at a previously defined location in memory. The normal program called at every clock tick updates the time of day and turns off disk drive motors that have run too long. After completing its task, the interrupt routine returns the -2- Silence Version 2.0 computer to doing exactly what it was doing before the interrupt. Sound Generation Sound in the IBM PC is generated by a timer. The timer is loaded by a program with the desired frequency (pitch) and begins to run. The timers output tone goes to a gate controlled by the computer. The gate is connected to the speaker and allows the tone supplied by the timer to be turned on and off. Silence Silence operates by taking over the interrupt generated by the system clock. Every time the clock ticks, Silence is called instead of the normal time of day routine. Once called, Silence turns off the gate to the speaker and sets up the timer so that it produces a click instead of a tone. After this, Silence passes control to the normal clock tick routine so that the time of day and disk drives will operate normally. In this way, when a program produces a tone, the tone will be turned off after 1/18.2 of a second and the timer will only produce a click. It is possible for a program to set the computer to ignore the system clock tick. When a program does this, Silence is temporarily disabled and cannot turn off the sound. This summary has only covered Silence's basic operation. Silence's advanced options such as Burst Delay and Acceleration alter certain aspects of the way Silence works to provide the user with greater silencing power. These options are described more fully below. Options There are several options that may only be changed by using the function access screen. To display these options enter Sil2 (or "Sil2 c" or "Sil2 m" if your adapter is non-standard). The function access screen will be displayed along with the current settings of the options. To change the settings use the return key to tab to the desired option, select a setting from the menu, and hit the return key. If you make a mistake, the backspace key can be used to correct it. To exit from the function access screen either hit the return key to tab to the end of the screen or hit the escape key to exit immediately. If you select a setting from the menu and hit the escape key instead of the return key your selection will be ignored, the function access screen will be exited, and the setting of the option will not be changed. -3- Silence Version 2.0 The available options are as follows: Silence 1. On 2. Off Timer Mode 1. Program Controlled 2. Beep 3. Click Speaker Enable 1. Program Controlled 2. Silence Controlled Burst Delay 1. Off 2. 1 Sec. 3. 2 Sec. 4. 5 Sec. 5. 10 Sec. 6. 15 Sec. Acceleration 1. 1X (off) 2. 5X 3. 10X 4. 50X 5. 100X 6. 255X Blink 1. On 2. Off Silence Silence On and Off perform as described in the command section. Timer Mode Timer Mode controls the mode Silence uses at every clock tick to reset the timer that produces the tones. The default is to reset the timer to produce clicks. If you change the setting to Beeps with the Speaker Enable under control of Silence, short beeps will be produced instead of clicks. If you set the Timer Mode for Program Control, Silence will not alter the mode of the timer. Speaker Enable Speaker Enable allows the speaker to be under control of Silence or the users program. Under Silence's control the speaker will be turned off at every system clock tick. If option 1 is selected Silence will leave the speaker alone. Setting the Timer Mode and Speaker Enable to Program Controlled with the Burst Delay, Acceleration, and Blink off is the same as turning Silence Off. Burst Delay Burst Delay is an advanced option that is useful in certain situations. Not all programs work normally with the Burst Delay option activated. Burst Delay waits the selected amount of time before passing along any system clock ticks to other interrupts. When the Burst Delay period expires the clock ticks which occurred during the delay are passed along all at once. If a game program is using the system clock to generate continuous melodies the Burst Delay option -4- Silence Version 2.0 will cause the program to emit a long pause followed by an unrecognizably short burst of sound consisting of all the tones that would normally have occurred during the pause. Acceleration Acceleration controls the speed of the system clock. Normally, the system clock produces about 18.2 clock ticks every second. The Acceleration option allows you to change the number of clock ticks produced per second from 18.2 to over 4,000. Because Silence turns off the speaker at every clock, there are instances where turning the speaker off up to 4,000 times a second can be much more effective than turning it off 18.2 times a second. Acceleration is not compatible or effective with all programs. If a program takes over the system clock (most do not), the accelerated clock may cause erratic behavior or lock up. If a program turns off the interrupts while producing sound, Acceleration will have no effect. It is recommended that Acceleration only be used when necessary. Do not routinely set Acceleration to 255X every time Silence is initialized. Use Acceleration only with those programs with which it is needed, effective and compatible. Using Burst Delay and Acceleration The Burst Delay and Acceleration options are not designed to be used with all programs or at all times. These options are provided to give you, the user, more powerful tools for silencing toublesome programs. The best course to follow is to experiment to find the most effective and compatible settings for each program. Don't be surprised if some programs behave erratically or even lock up with some Burst Delay and Acceleration combinations. On the other hand, these options can be great fun (especially with on screen clocks), so don't be afraid to experiment. If you have any questions or serious problems, please contact me. Blink Blink, when activated, puts a small square in the upper left corner of the screen and turns it on and off once a second. Blink is a continuous visual reminder of the status of Silence. If Silence is turned off, or if a program takes over Silence's interrupt, the box will no longer blink. In graphics modes Blink's box will appear as a short flashing line. If you have a color monitor and adapter, Blink causes a very small amount of "hash" to appear on the screen. If you find this to be extremely offensive, let me know. -5-