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8255 – PROGRAMMABLE PARALLEL PORT DEVICE. METHODS OF PARALLEL DATA TRANSFER SIMPLE INPUT AND OUTPUT SIMPLE STROBE I/O SINGLE-HANDSHAKE I/O DOUBLE HANDSHAKE.

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Presentation on theme: "8255 – PROGRAMMABLE PARALLEL PORT DEVICE. METHODS OF PARALLEL DATA TRANSFER SIMPLE INPUT AND OUTPUT SIMPLE STROBE I/O SINGLE-HANDSHAKE I/O DOUBLE HANDSHAKE."— Presentation transcript:

1 8255 – PROGRAMMABLE PARALLEL PORT DEVICE

2 METHODS OF PARALLEL DATA TRANSFER SIMPLE INPUT AND OUTPUT SIMPLE STROBE I/O SINGLE-HANDSHAKE I/O DOUBLE HANDSHAKE I/O

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5 HANDSHAKE INPUT DATA TRANSFER SIGNAL DIRECTIONS MICRO- PROCESSOR PERIPHERAL PARALLEL DATA LINES PORT DEVICE STB ACK

6 Need of 8255 The parallel port device 8255 has been designed to automatically manage the handshake operation. Eg, it can be programmed to automatically receive an Strobe signal from a peripheral, send an int signal to the processor and send the ACK signal back to the peripheral at proper times

7 8255 – Internal block diagram

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18 Note: 8255 is often used in mode 1

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