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16: How can I clear the keyboard type-ahead buffer?A: Three methods are usually suggested for solving this problem. a) The first is to use something like uses Crt; while KeyPressed do ReadKey; This kludge-type method has the disadvantage of requiring the Crt unit. Also, in connection with procedures relying on ReadKey for input, it may cause havoc on the programs logic. b) The second method accesses directly the circular keyboard buffer var head : word absolute $0040:$001A; tail : word absolute $0040:$001C; procedure FLUSHKB; begin head := tail; end; For a slightly different formulation of the same method see Michael Tischer (1992), PC Intern System Programming, p. 462. c) The third method is to call interrupt 21Hex (the MS-DOS interrupt) with the ax register set as $0C00. This method has the advantage of not being "hard-coded" like the second method, and thus should be less prone to incompatibility. |
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