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- OSMKCM03
- 09/02/94
-
-
- ================================================================
- Configuring OS/2 2.x for Asynchronous Communications.
- ================================================================
-
-
- SYMPTOMS:
-
- My modem doesn't work.
-
- My modem hangs the system or session when I try to use it.
-
- My modem works in native DOS and Windows but doesn't work in OS/2,
- WIN-OS/2 or DOS-OS/2.
-
- After installing OS/2 for Windows my modem doesn't work under OS/2.
-
-
-
- RESOLUTION:
-
- 1. Configure Hardware.
-
- 2. Configure device driver for com3 and com4.
-
- 3. Configure device driver for non default com1 and com2.
-
- 4. Configure DOS settings .
-
- 5. Configure application.
-
-
-
- PROCEDURES:
-
- 1. The original ISA machine (the IBM PC-AT) allowed for the
- definition of up to four serial communications ports. However,
- there has never been any hardware architectural standard that
- defined the I/O port addresses or Interrupt Request (IRQ) lines
- associated with communication ports #3 or #4. Over the years a
- convention was established which places the port addresses for
- COM3 and COM4 at 03E8 and 02E8 respectively. This is a
- generally accepted convention, not a standard. If multiple
- hardware adapters of any kind (not just communications) are
- using the same I/O address, the effect on your system can
- be unpredictable.
-
-
-
- OS/2 2.0 is an interrupt driven operating system and requires
- unique I/O addresses and Interrupt Request lines (IRQs) for each
- adapter in the system on an ISA computer system. If two
- adapters are sharing the same PHYSICAL IRQ, the processor
- does not know which adapter (and therefore which OS/2 session)
- should get the Interrupt Request (IRQ). In a single tasking
- operating system such as DOS, the sharing of interrupts is not a
- problem as only one application is in use at a time. OS/2
- presents a different set of problems. If you have
- three, or four serial communications adapters, the probability
- is high that you might try to use two or more of them
- at the same time. If some of them have previously been set up
- using share interrupts, then the stage is set for things to
- happen that probably didn't happen under DOS.
-
-
- To avoid these problems, make sure that all of your hardware
- adapters have their own unique I/O addresses and IRQ assignments.
- OS/2 has no way to query an ISA computer to find out what these
- settings are. Check and set the adapter according to the
- documentation. Include IRQ Base I/O DMA for each slot. This is
- handy if you decide to add more adapters at a later time.
-
-
-
- 2. The OS/2 2.x COM.SYS driver recognizes the COM1 at I/O address
- 03F8, IRQ4, and COM2 at I/O address 02F8, IRQ3 (these are known
- as the default standards). It does not know about any other
- configurations and requires the following parameters to function
- with configurations that vary from the default standard.
-
-
- In the CONFIG.SYS file use an editor to make appropriate
- changes.
-
- valid parameters for COM.SYS:
-
-
-
- DEVICE=X:\OS/2\COM.SYS (n, a, i, s, f)
-
-
- X = the drive OS/2 has been installed on
-
- n = the communications port number (1,2,3,4)
-
- a = the port I/o address in hex (03F8, 02F8, 2320)
-
- i = the IRQ level (3,4,5,....15 decimal)
-
- s = the spurious interrupt handler (optional).
-
- D = disable driver if spurious interrupts are greater than
- 1000.
-
- I = ignore (default setting, need not include)
-
- f = 'F' to indicate a 100% buffered NS16550a compatible UART.
-
- EXAMPLE:
-
- DEVICE=X:\OS/2\COM.SYS (1, 3F8, 5, d, f) - used when
- COM1, I/O ADR. 03F8, uses a non-default IRQ of 5, the
- driver is disabled if more than 1000 spurious interrupts
- are received, and a NS16550 (buffered) UART is in use.
-
-
- DEVICE=X:\OS/2\COM.SYS (3, 3E8,10, D) - used when COM3,
- I/O ADR. 03E8, uses a level 5 IRQ and the driver unloads
- if spurious interrupts are greater than 1000.
-
-
- 4. Make sure the DOS settings have the following settings:
-
- COM_DIRECT_ACCESS = OFF
-
- COM_SELECT = ALL or COMx (x = the port the application
- is using)
-
-
-
- 5. Make sure the application is configured for the correct port
- and line settings.
-
- EXAMPLE:
-
- COM3 8bits 1stop no parity 9600baud
-