                I/O Address
                -----------

        (Version for Pasokon TV Classic.)

What is an I/O Address?
-----------------------

Your computer is composed of several sub-systems:
 - Central Processing Unit (CPU), such as a '486.
 - Memory.
 - Input/Output (I/O) devices such as a keyboard, printer
   port, and video display.

The CPU does not have separate wires going to each of the
I/O devices.  Instead they are all connected to a common set
of connections called a "bus."  Memory and I/O devices respond
only when their particular address is on the bus.

The original IBM PC had the ability to use 1024 different
I/O addresses.  Very simple devices might use only a single
address, more complicated devices require several adjacent
addresses.  I/O addresses are usually written as hexadecimal
(base 16) numbers in the range of 000H through 3FFH.  Often
an H is written at the end of a number to indicate hexadecimal.

Addresses 000H through 1FFH are normally used for devices
on the mother board such as timers, interrupt controllers,
the real-time clock, math coprocessor, and CMOS memory 
holding configuration information.

Addresses in the range of 200H through 3FFH are used for 
peripheral devices.  These have traditionally used plug in
cards but many newer computers have standard devices built
in to the mother board.

Most of the standard devices, such as printer ports, serial
(COM) ports, video display, and the floppy disk controller
use addresses in the 300H to 3FFH range.  The 2xx range was
mostly unused in the original PC and that is why most add-on
devices, such as sound cards, CD-ROM drives, and Pasokon TV
use addresses in the 2xx range.

Clearly the hardware and software configuration must agree.
If a serial port is listening to address 3F8H, the software
must write to that address, to use the serial port.

Two different devices may not share the same address.  It would
cause great confusion if two different devices responded to
the same address and tried to put their data on the bus at
the same time.


I/O Address Selection
---------------------

Pasokon TV requires a range of 32 I/O addresses.  There are
8 different jumper positions on the board to select a range.

        +-----------------------------------------+
        |                                   R16   |
        |                                   C12   |
        |                                         |
        |                                        ###
        |                                        ###
        |                    200 ... 2E0         ###
        |                     ########           ###
        |                     I/O Addr           ###
        |                                         |
        +----------+       +--+              +----+
                   +-------+  +--------------+
                   Edge connector for PC slot.


These are the jumper positions, address ranges, and likely
conflicts for those ranges:

        Jumper          Range           Conflicts
        ------          -----           ---------
        200             200 - 21F       Game Port
        220             220 - 23F       Sound, CD-ROM
        240             240 - 25F
        260             260 - 27F       Printer port 2
        280             280 - 29F       **
        2A0             2A0 - 2BF
        2C0             2C0 - 2DF
        2E0             2E0 - 2FF       Serial ports 2 + 4


The Creative Labs Sound Blaster uses 220 - 23F as the default
location but it can be set to others.  I don't know about the
standard locations for other brands.  Maybe someone could tell
me and I'll put the information here.

In the case of the Sound Blaster, you should find a line
like this in the AUTOEXEC.BAT file:

        SET BLASTER=A220 I5 D1 H5 P330 T6

The "A220" means it is using I/O Address 220.
The "I5" means it is using interrupt 5.


** The factory default setting for Pasokon TV is 280.
I have never heard of a conflict with another device at this
address.  


Error Message
-------------

It is possible that you will see and error message resembling:

        Interface does not respond to I/O address 2xx.

Possible causes:
 - Interface is not installed in computer.
 - Jumper position and software configuration do not agree.
 - There is a conflict with another device using same I/O
   addresses.


Solution
--------

1. Examine the Pasokon TV interface and set the I/O address
   jumper to the desired position.  The two end positions would
   be very bad choices.  Avoid conflicts with any other devices
   such as a sound card or CD-ROM drive.
   When in doubt, use 280.  Write this number down.

2. Put the interface back in the computer and run PKTV.

3. Pick "I/O Address" under the "Setup" menu.
   Select the button corresponding to the jumper position.
   Note that a limited selection is available to make it more
   difficult to make a poor choice.  All the possibilities are
   available by manually editing the PKTV.CFG file.

4. Click on the "Recv" button or press Enter key to start 
   receiving.  If you get the "Interface does not respond ..."
   message, call us for assistance.  If you get a message about
   the interface not generating interrupts the I/O address is
   probably OK.

