DIGITAL INPUT/OUTPUT CARD IOD-144 USER MANUAL
6-1
PROGRAMMING

The IOD-144 is an I/O mapped device that is easily configured from any language and any

language can easily perform digital I/O through the card'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. Follow the

8255-5 Specification in APPENDIX A to program the PPIs on the IOD-144 Digital

Input/Output Card.

A total of 24 address locations are used by the IOD-144 for addressing the PPIs; four for

each PPI. The PPIs are addressed using address bits A3 through A0 (See Address

Selection, section 4 of this manual.) as follows:

PORT ADDRESS SELECTION TABLE

Address Port Assignment Operation
Base Address
Base Address +1
Base Address +2
Base Address +3
Base Address +4
Base Address +5
Base Address +6
Base Address +7
Base Address +8
Base Address +9
Base Address +A
Base Address +B
Base Address +C
Base Address +D
Base Address +E
Base Address +F
Base Address +10
Base Address +11
Base Address +12
Base Address +13
Base Address +14
Base Address +15
Base Address +16
Base Address +17
PA Port 0
PB Port 0
PC Port 0
Control Port 0
PA Port 1
PB Port 1
PC Port 1
Control Port 1
PA Port 2
PB Port 2
PC Port 2
Control Port 2
PA Port 3
PB Port 3
PC Port 3
Control Port 3
PA Port 4
PB Port 4
PC Port 4
Control Port 4
PA Port 5
PB Port 5
PC Port 5
Control Port 5
Read/Write
Read/Write
Read/Write
Write Only
Read/Write
Read/Write
Read/Write
Write Only
Read/Write
Read/Write
Read/Write
Write Only
Read/Write
Read/Write
Read/Write
Write Only
Read/Write
Read/Write
Read/Write
Write Only
Read/Write
Read/Write
Read/Write
Write Only