Changes
8255
,* Setting bit 7 of port C to 1,
<pre>
LD B,&F7 ;8255 Control port
LD A,%00001111 ;Bit Set/reset function
OUT (C),A ;Send it to 8255
RET
</pre>
* Set port A to input, operating in mode 0, port B to output, operating in mode 0 and port C to input, operating in mode 0.
<pre>
LD B,&F7 ;8255 Control port
LD A,%10011001 ;Configuration function
OUT (C),A ;Send it to 8255
RET
</pre>
2. Using port A/B/C,
* Reading from port A,
<pre>
;Set port A to input
OUT (C),A ;Send to 8255
RET
</pre>
* Writing to port A,
<pre>
;Set port A to output
OUT (C),A
RET
</pre>
= Diagrams =
[Image:8255 ppi 1.jpg]]
[Image:8255 ppi 2.jpg]]
= Resources =
[[Media: |Datasheet of the 8255]]
= Links =
[http://en.wikipedia.org/wiki/Intel_8255|Wikipedia about the 8255ppi]
