Although cryptic, data sheets contain all of the detailed information about a particular device. But, be warned!, they are sometimes inaccurate due to typos and poor editing. The data sheets on the following pages of the 8255 PPI seem to be accurate.

1. ▪ I MCS-85TM Compatible 8255A-5

2. ▪ 24 Programmable I/O Pins

3. ▪ Completely TTL Compatible

4. ▪ Fully Compatible with Intel Microprocessor Families

5. ▪ Improved Timing Characteristics

6. ▪ Direct Bit Set/Reset Capability Easing Control Application Interface

7. ▪ Reduces System Package Count

8. ▪ Improved DC Driving Capability

9. ▪ Available in EXPRESS

10. — Standard Temperature Range

11. — Extended Temperature Range

12. ▪ 40 Pin DIP Package or 44 Lead PLCC (See Intel Packaging: Order Number: 231369)

The Intel 8255A is a general purpose programmable I/O device designed for use with Intel microprocessors. It has 24 I/O pins which may be individually programmed in 2 groups of 12 and used in 3 major modes of operation. In the first mode (MODE 0), each group of 12 I/O pins may be programmed in sets of 4 to be input or output. In MODE 1, the second mode, each group may be programmed to have 8 lines of input or output. Of the remaining 4 pins, 3 are used for handshaking and interrupt control signals. The third mode of operation (MODE 2) is a bidirectional bus mode which uses 8 lines for a bidirectional bus, and 5 lines, borrowing one from the other group, for handshaking.

General

The 8255A is a programmable peripheral interface (PPI) device designed for use in Intel microcomputer systems. Its function is that of a general purpose I/O component to interface peripheral equipment to the microcomputer system bus.