8255 Programmable Peripheral Interface

         In this post, we are going to learn a very old grand father of modern processors, named 8085 and his colleague 8255. Pins, Signals and internal block diagram of 8255:   The internal block diagram of 8255 is shown in fig:   The 8255 can be either memory mapped or I/O mapped in the system. In the schematic shown in above is I/O mapped in the system.   Using a 3-to-8 decoder generates the chip select signals for I/O mapped devices.  The address lines A4, A5 and A6 are decoded to generate eight chip select signals (IOCS-0 to IOCS-7) and in this, the chip select IOCS- 1 is...

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