TSOUND v1.2 Copyright (C) 1991 PC Enterprises 1-908-280-0025 Permission is granted to distribute TSOUND.COM and TSOUND.DOC free of charge provided the two programs are distributed together and no portion of either program and/or the contained messages have been altered. Dedicated exclusively to the support of the IBM PCjr since 1984. PCjr owners can receive a FREE PCjr products catalog by calling 1-800-922-PCJR TSOUND.COM is a PCjr utility for controlling the PCjr's enhanced sound capabilities as well as PC Enterprises' Tandy Sound Modification which adds Tandy four voice sound. For more information about these system board enhancements, call either of the two phone numbers listed above. HISTORY OF PC, PCjr, AND TANDY 1000 SOUND SUBSYSTEMS: To understand what TSOUND.COM can do, you should first understand more about your PCjr's sound subsystem and how the PCE Tandy Sound modification adds to those capabilities. The original IBM PC produced sound through a small speaker mounted on the system board. It could play a wide variety of tones by using a programmable timer chip to modulate the speaker with digital information, but only at a fixed volume. Using this design, the PC can play only one tone at a time and only at one volume level. PC compatible sound is therefore primarily used to produce beeps for signaling certain events. The PC also has BIOS support to emulate an on-off switch between the timer and system board speaker. In this document file this feature is referred to as the system board speaker switch. In most cases, this feature gives software the ability to turn off the system board sound, however because the hardware does not actually include a physical switch, the system board speaker can still beep under certain conditions such as during an error. When the PCjr was designed, it was obvious to IBM that the PC's single voice beeper alone would not impress the home computer market. As a result, the PCjr received a special sound chip which is known as the Complex Sound Generator (CSG). This chip can play three tones and one noise simultaneously. Each voice of the CSG is completely independent, each having its own frequency and volume control. Nevertheless, even with these new capabilities, it was still very important to remain 100% compatible with the PC's sound subsystem since many PC programs were already coded to use it. When the PCjr is first powered on, the PC compatible sound subsystem is automatically selected. This means the system board speaker is turned on. In addition, the PCjr's enhanced sound subsystem, which always produces sound through the external speaker, is also set up to produce PC compatible beeper sound. When a PC compatible program produces sound, it will be heard through both speakers. Software designed to use the CSG can then select the CSG when necessary, by using a multiplexor which is part of the PCjr's sound subsystem. A multiplexor is something like an electronic switching box that allows one of four inputs to be selectively connected to the PCjr's external speaker. The PCjr's sound system, through use of the multiplexor, can allow the sound from either its programmable timer chip, CSG, cassette I/O, or external input to be heard through the external speaker. If software knows it's running on a PCjr and was designed to use the CSG, all the software has to do is make the multiplexor select the CSG instead of the programmable timer and then send the music data to the CSG. Since the programmable timer gets selected automatically by the PCjr when the computer is powered on, software designed to use the PC's sound subsystem and not the CSG, works fine. The software just sends the PC compatible sound data to the programmable timer chip without requiring the multiplexor to change its default setting. This way the PCjr has the best of both worlds, PC compatibility and enhanced sound. When Tandy came out with their 1000 computer, it was clear that they had based their designs on the PCjr. They did, however, improve the sound system. While retaining the beeper and the CSG designs, they added a feature which allows software to select both, the PC compatible beeper and the CSG sound, at the same time. The PCE Tandy Sound Modification eliminates this difference. Once this modification is installed the PCjr, like the Tandy, it can play four tones concurrently through the external speaker by using the multiplexor to select an input that has the timer chip and CSG together on one channel. Since all Tandy 1000s were shipped with a diskette drive, there was no need for cassette recorders, so cassette support was dropped in favor of four voice sound. When the Tandy Sound Modification is in use on the PCjr, cassette support is disabled. USING THE TSOUND.COM UTILITY: Running TSOUND.COM without any parameters will report the current settings for the sound subsystem. It will report the current state of the system board speaker switch and multiplexor. It will also report whether the PCE Tandy Sound Modification has been installed. Running TSOUND.COM with the /? option will display a help screen that shows all the options of the TSOUND utility. The /T option will cause the single voice beeper and all three voices of the CSG to play tones, testing and demonstrating the current settings of the computer's sound subsystem. Whether the sounds being played can be heard through the external speaker or system board speaker is determined by the state of the multiplexor and the state of the system board speaker switch. If you have the PC Enterprises' Tandy Sound Modification and are about to run a Tandy program that supports Tandy four voice sound, run the TSOUND utility with the /4 option. This will permit the PCjr to produce up to four sounds through the external speaker (This option allows Tandy software to produce one, two, three, or four voice sound). There is usually no need for selecting the External Input option (/E) for other than experimentation or for turning off the external speaker. At this time, this input is selected only by programs that support the IBM PCjr Speech Attachment. Future PCE sound products will most likely make use of this input also. There is also no need to select the Cassette (/C) option for other than experimentation. Programs that use cassette drives will automatically select this channel to store and retrieve data from cassette as necessary. The IBM PCjr sound subsystem: /³ ÚÄÄÄÄÄÄÄÄÄÄÄ/ ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ< ³ ³ System board speaker switch \³ ³ System board speaker ³ ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ» Programmable Timer ÄÄÄÄÁÄÄÄÄÄÄÄĶ Oº ºI uº /³ CSG ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄĶn Multiplexor tº / ³ ºp pÇÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ< ³ Cassette I/O ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄĶu uº \ ³ ºt tº \³ External input ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄĶ º External speaker ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ Note: These diagrams may not be able to be duplicated on some printers. To print a copy of this document enter the following command at the DOS prompt: COPY TSOUND.DOC PRN: