Accessible pinout for 8255A

Part description: Programmable Peripheral Interface, PDIP-40

Package description: This package has two parallel rows of pins extending down from opposite edges of the chip.

There should be a semicircular notch that you can feel in the middle of one of the package's shorter bare edges. With the pins facing downward and the chip oriented so notch is on the side of the chip furthest from you, Pin 1 will be in the far left corner of the chip.

Pins are numbered counter-clockwise. Numbers increase from the far left corner to the near left corner. They then continue on the right side, increasing from the near right corner to the far right corner. Thus the highest number pin is to the right of pin 1.

Pin assignments

Left side (numbering starts at far end)

Pin Signals
1PA3
2PA2
3PA1
4PA0
5RD (active low)
6CS (active low)
7GND
8A1
9A0
10PC7
11PC6
12PC5
13PC4
14PC0
15PC1
16PC2
17PC3
18PB0
19PB1
20PB2

Right side (numbering starts at near end)

Pin Signals
21PB3
22PB4
23PB5
24PB6
25PB7
26VCC
27D7
28D6
29D5
30D4
31D3
32D2
33D1
34D0
35RESET
36WR (active low)
37PA7
38PA6
39PA5
40PA4

This pinout was automatically generated from the KiCAD symbol library revision 164574.

It is possible that there may be a mistake in the source data leading to wrong information on this page.