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- //-----------------------------------------------------------------------//
- // //
- // Plug & PLay Modem Installation Software //
- // Verison 1.23 //
- // //
- // SHARK MULTIMEDIA April 1995 //
- //-----------------------------------------------------------------------//
-
- Table of Contents
-
- 1. Installation overview
- 2. Modem Tutorial
-
-
- [INSTALLATION OVERVIEW]
-
- OBJECTIVE:
-
- This software is designed to permit SIERRA MULTIMEDIA Plug-and-Play
- modems to be "automatically" installed and configured into IBM PC's and
- compatibles that have no other Plug-and-Play capabilities (ie. machines
- that have neither PNP BIOS nor are running Microsoft CHICAGO.)
-
- The Plug-and-Play capabilities of the SIERRA modem have eliminated the
- jumpers (or DIP switches) normally needed for configuring the modem.
- Instead, the modem can be configured in software.
-
- INSTALLATION PROCEDURE:
-
- The installation procedure is divided into several parts:
-
- 1) The software in the diskette is copied to the harddisk of the
- target computer.
-
- 2) Changes are made to the CONFIG.SYS file.
-
- 3) A diagnostic routine is run to assess which computer resources
- are in use and which are available for the new modem.
-
- 4) The recommended choice of modem settings is presented to the
- user. These settings, which may be modified by the user, are
- then are stored in a file.
-
- 5) The settings are 'sent' to the modem to configure it.
-
- 6) The modem is "locked" so that on subsequent boot-ups, the modem
- will maintain the same settings.
-
-
-
- ACTUAL INSTALLATION PROCEDURE:
-
- 1) Turn off power and install the new modem.
-
- 2) Power up the computer.
-
- 3) Insert disk in A: drive, type:
-
- A:
- install
-
-
- AFTER INITIAL INSTALLATION:
-
- Once this configuration software is installed on your harddisk, you
- can change the configuration of the modem or install additional
- modems by going to the C:\SSMODEM directory and running "CONFIG.EXE" .
-
- [COM TUTORIAL]
- TUTORIAL ON COM PORTS, INTERRUPTS, AND MODEMS
- =============================================
-
-
- Objective:
-
- This tutorial is geared to help the computer novice understand enough
- about the way computers and modems operate so that a Plug-and-Play
- modem can be successfully installed.
-
-
- Background:
-
- Electrically speaking, the architecture of the PC was largely defined by
- IBM in 1980, when the first PC was introduced. Since that time there have
- been many improvements, especially in disk drives and in the main CPU
- (ie. 8088 > 80286 > 80386 > 80486 > Pentium ). But there has been no
- significant changes in the way computers interface to modems.
-
- Fortunately, IBM had a great deal of insight into computers and so they
- understood that to have a good computer it needed to support several
- input/output devices....things like a keyboard, a screen, and a printer.
- They also could foresee additional devices likes modems.
-
- A modem is a serial device, that is, it sends information one bit at a
- time, in sequential (serial) fashion. Besides modems, there are many
- other serial devices: most mice are serial, a few printers are serial,
- and many specialized peripherals are serial.
-
- The original designers of the PC decided to include support for up to
- four serial devices. For each of these, they reserved the appropriate
- resources, and labeled these serial "ports" COM1, COM2, COM3, and COM4.
- Only one serial device may use one of these ports at any given time.
- Each serial device, be it modem, mouse, or whatever, must be electrically
- configured for the com port that it is to use. With regard to this
- configuration, there are two very important issues:
-
- 1) The computer needs to "know" which port to use for the mouse,
- which port to use for the modem, etc. This is normally done
- by setting configuration parameters in the application software
- that is to be used.
-
- 2) Each serial device needs to be configured to a port that no other
- device is using. If two device are trying to send and receive
- information through the same port, it is kind of like trying to
- talk on the telephone on a party line where several people are
- talking at once. The result is confusion.
-
- Most modems can be configured for any of the four standard COM ports.
- All COM ports are created equal, you won't get better performance using
- COM1 instead of COM2, etc.
-
- A logical question at this point may be, how do I know which COM ports
- are currently in use and which ones are 'free'? That is a good
- question. The easiest way to find out is to use diagnostic software that
- can survey your system and determine which resources are available.
- There are many good diagnostic packages available, like QAPlus, Modem
- Doctor, and Portinfo. There is a very good one that Microsoft
- supplies with Windows called MSD. It must be run from the DOS command
- line. But the real answer to the question is: "You don't really need
- to know, because the automatic configuration software runs a diagnostic
- utility and presents you with the available choices.
-
-
- The second part of the configuation is proper selection of interrupts.
- First a little background on interrupts. If we consider each of the
- four COM ports to be like an IN-BASKET on a desk, the CPU would have to
- continually stop whatever it's doing to look and see if anything is in any
- of the IN-BASKETs. Actually it would need to stop about a thousand times
- in each second to figure out if any information had been received. This
- technique is called polling, and is generally undesirable because it uses
- valuable CPU time and slows down the applications that are running. What
- would be great would be if the IN-BASKET could "ring a door-bell" any
- time some data came in. In a house, frequently the front door and back
- door have different (distinctive) chimes. That way when one 'rings', you
- know exactly which door to answer. Now imagine that you had 16 different
- doors with 16 different chimes. That is exactly what happens in the
- computer. There are 16 different interrupts, labeled IRQ0, IRQ1,...IRQ15.
- In theory, you can assign any one of the 16 interrupts to any of the four
- COM ports. In practice, however, there are several constraints:
-
- 1) Several of the interrupts are already dedicated to important tasks,
- like disk drives, the printer, the mouse, etc.
-
- 2) Modems can physically generate only a few of the interrupts. Nearly
- all can support IRQ3 and IRQ4. A few can also support IRQ5 and/or
- IRQ7. (The Shark Plug-and-Play modem can support IRQs 3,4,5,7,10.
-
- 3) For each IRQ, it is highly desirable to have only one device that can
- generate it.
-
- In the original IBM design, two interrupts (IRQ3 and IRQ4) were 'reserved'
- for use with the four COM ports. There is a recommended association as
- follows:
- COM1 IRQ4
- COM2 IRQ3
- COM3 IRQ4
- COM4 IRQ3
-
- The intent, it seems, is that only two of the ports can be active at any
- time. The pairings shown above are not cast in stone. They may be changed,
- and also, other IRQs can be used providing that both the modem and the
- application software can support the new combination.
-
- In a simple scenario, the mouse may be using COM1/IRQ4 and no other COM ports are
- active. To install a new modem, the logical selection is to use COM2/IRQ3.
-
-
- Again, if you want to know what IRQs are currently in use, diagnostic
- software will give you the information.
-
-
-
- RECOMMENDATIONS:
-
-
-
-
-
- EXAMPLES:
-
-
-
- PROBLEMS:
-
-
-
-
-