What are the three types of key entry modes available in 8279?

1.	What are the three types of key entry modes available in 8279?
Answer» MODES OF OPERATION INPUT (KEYBOARD) MODE Three input modes: 1. Scanned keyboard mode : allows key matrix to be interfaced either in encoded mode or decoded mode . In decoded mode 4 x 8 matrix is interfaced and in encoded mode 8 x 8 keyboard is interfaced. The code key pressed with CNTL and SHIFT is stored in FIFO RAM. 2 .scanned sensor mode : in encoded mode 8 x 8 sensor matrix and in decoded mode 4 x 8 sensor matrix is interfaced 3. Strobbed input : if control line goes low data on return line is stored in FIFO byte by byte.

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MODES OF OPERATION INPUT (KEYBOARD) MODE

Three input modes:

1. Scanned keyboard mode : allows key matrix to be interfaced either in encoded mode or decoded mode . In decoded mode 4 x 8 matrix is interfaced and in encoded mode 8 x 8 keyboard is interfaced. The code key pressed with CNTL and SHIFT is stored in FIFO RAM.

2 .scanned sensor mode : in encoded mode 8 x 8 sensor matrix and in decoded mode 4 x 8 sensor matrix is interfaced

3. Strobbed input : if control line goes low data on return line is stored in FIFO byte by byte.

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