Allen-Bradley 1784-KT/B - Page 14

Communication Interface Module
Cat. No. 1784KT/B
Installation Data
14
Information is passed between the computer system and the 1784-KT
through 2 Kbytes of memory located in the interface module. This 2 Kbyte
memory is memory mapped into an open memory location in your
computer system. The definition of “open” is a location that has not been
configured for another optional interface card or system. The 1784-KT
address decoding allocates a 16 Kbyte memory location. So, when
selecting an open memory location, make sure there is a 16 Kbyte block.
Also, the definition of open applies to hardware system interrupts.
Depending on the interface card you have installed into your computer,
only a few select interrupts may be open for the 1784-KT.
Let’s say the targeted computer for installing a 1784-KT is an IBM PC-AT
with the following options:
640 K System Memory 00000:000009000:FFFF  
EGA Card 0A000:00000A000:FFFF  
Color Monitor 0B000:00000B000:FFFF  
Diskette Drive  3F03F7 IRQ 6
Hard Drive  1F01FF IRQ 14
Serial Port Card  2F82FF IRQ 4
(Configured for port 1)
The memory map for this system would be what is documented in the
“System Memory Allocation Worksheet” (see page 15) for the IBM
PC-AT. Open memory for a 1784-KT would be from 0B800:0000 to
0DF00:0FFF. By using the memory default setting, the 1784-KT would fit
into this open memory at locations 0D400:0000 to 0D700:0FFF.
The 1784-KT supports four interrupts: IRQ3, IRQ4, IRQ5, and IRQ7.
Refer to the “Hardware Interrupt Allocation Worksheet” (page 17) for the
IBM PC-AT for possible open interrupts. Only IRQ4 is used for the serial
port card configured for port 1. The 1784-KT uses the “no interrupt”
setting as the default.
Use the following worksheets to help manage your system’s memory, I/O,
and interrupt assignments. The IBM PC-AT and IBM PC-XT system
assignments have been chosen as a reference. These IBM assignments are
available in their respective IBM Technical Manuals and are subject to
change by IBM.
Important: The 1784-KT does not require a system I/O address. The
1784-KT only uses addressable memory and an interrupt. The I/O map is
provided so that you can document your entire computer system.
To use the worksheets, enter your computer’s memory, I/O, and interrupt
assignments in the column labeled “Your System” .
System Memory and
Interrupts