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 Device driver for IBM 5150 PC's serial port (AUX)  J. Eric Roskos 23.08.1984

Драйвер последовательного порта для IBM 5150.
Device driver for IBM 5150 PC serial port.



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Device driver for IBM 5150 PC's serial port (AUX). By J. Eric Roskos Public Domain, may not be sold for profit. This driver is initialized by calling AuxInit, and MUST be deactivated by calling AuxOff before the program exits (or a sub- sequent serial interrupt will cause the system to hang). It uses serial interrupts, and thus works considerably better than the standard AUX device driver supplied with the IBM PC. Once AuxInit is called, you can read and write to the predefined Turbo Pascal file "Aux" to access the serial port. The procedure AuxSt returns True if a character is presently available at the serial port, equivalent to the KeyPressed procedure for the console. You don't have to (and shouldn't) call any of the other procedures in this file other than AuxInit, AuxOff, and AuxSt. Presently, only input is done via interrupts; output is via conventional polling, and a write to the serial port will cause a busy-wait until any previous character is completely transmitted. The input buffer's size is defined by the constant BUFSIZ below, which must be a power of 2 (or the wrap-around algorithm won't work). The serial port is presently initialized to 1200 baud; if you want to set it via the MODE command of DOS instead, you can comment out the statements indicated below. If the input buffer becomes full, a ^S is sent to the remote machine; a ^Q is then sent when it empties sufficiently to resume. This is indeed used at 1200 baud if a number of escape sequences are sent in succession. Only the top 24 lines of the screen are used, in order to comply with most standard terminals. However, for this to work you have to compile the program with Turbo Pascal version 2.0 or later, and use an IBM PC version of the compiler (not the generic MS-DOS version).