B&B Electronics Parallel Port Input/Output Converter PPIO - Manual (Page 19)

PPIO2899 Manual
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17
For example:
Output_Byte
= 01010101b
Line_Number = 3
Status = 1
00000001b (1 decimal)
shift-right 3 (Line_Number) =
00001000b
XOR 11111111b
11110111b (mask 1)
AND 01010101b (Output_Byte)
00000001b (Status) 01010101b
shift-right 3 (Line_Number) = OR 00001000b (mask 2)
01011101b
(New Output_Byte)
For an example of an application that uses these functions, look
at the source code in PPIO.PAS.