EE 3750 — Homework 5 (revised version) due Mon., May 3, 2004 For all problems: state any assumptions made; include comments as needed to make assembly instruction sequences clear. 1. Write an 8086 instruction sequence to enable interrupts when Port A of an 82C55 (parallel interface) is ready for output and when Port B is ready for input where Groups A and B are in Mode 1. Assume that the modes and input/output directions of the 82C55 have already been initialized. Let 78H be the lowest port address for this 82C55. 2. Write an 8086 instruction sequence to initialize a 16550 UART. Set data length to 8 bits, use 1 stop bit, use odd parity, use a baud rate divisor of 60, enable and clear the FIFO queues, set the receiver trigger level to 1 byte in FIFO, and enable receiver interrupts. Let the low port address of the 16550 be 80H. Clearly state any additional assumptions that you make. Note: In addition to Brey §11-6 on the 16550, pp. 487-494 in §12-4 deal with interrupts and the 16550.
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