Manual P104-DIO-96
12
Chapter 5: Programming
The board is an I/O mapped device that is easily configured from any language and any language can
easily perform digital I/O through the board's ports. This is especially true if the form of the data is byte or
word wide. All references to the I/O ports would be in absolute port addressing. However, a table could be
used to convert the byte or word data ports to a logical reference.
Developing Your Own Software
If you wish to gain a better understanding of the programs listed in the previous section, then the
information in the following paragraphs will be of interest to you.
Four register locations are required per 24-bit group. Thus the 96 uses a total of 16 registers for groups 0
through 3.
Standard 8255 Compatibility Option
Improved Speed Option
Offset
Write
Read
Write
Read
Base+0
Group 0 Port A
Group 0 Port A
Group 0 Port A
Group 0 Port A
Base+1
Group 0 Port B
Group 0 Port B
Group 0 Port B
Group 0 Port B
Base+2
Group 0 Port C
Group 0 Port C
Group 0 Port C
Group 0 Port C
Base+3
Group 0 CMD
Group 1 Port A
Group 1 Port A
Base+4
Group 1 Port A
Group 1 Port A
Group 1 Port B
Group 1 Port B
Base+5
Group 1 Port B
Group 1 Port B
Group 1 Port C
Group 1 Port C
Base+6
Group 1 Port C
Group 1 Port C
Group 2 Port A
Group 2 Port A
Base+7
Group 1 CMD
Group 2 Port B
Group 2 Port B
Base+8
Group 2 Port A
Group 2 Port A
Group 2 Port C
Group 2 Port C
Base+9
Group 2 Port B
Group 2 Port B
Group 3 Port A
Group 3 Port A
Base+A
Group 2 Port C
Group 2 Port C
Group 3 Port B
Group 3 Port B
Base+B
Group 2 CMD
Group 3 Port C
Group 3 Port C
Base+C
Group 3 Port A
Group 3 Port A
Group 0 CMD
Base+D
Group 3 Port B
Group 3 Port B
Group 1 CMD
Base+E
Group 3 Port C
Group 3 Port C
Group 2 CMD
Base+F
Group 3 CMD
Group 3 CMD
Base+10
through
Base+1E
Reserved
Reserved
Reserved
Reserved
Base+1F
Reset Card
Reset Card
Table 5-1
: Base Registers
