Power Programmierung/Power-Programmierung (Tewi)(1994).iso/magazine/pcmagazi/1989/19/1stclass.doc

Text File | 1989-10-02 | 9KB | 183 lines

UTILITIES  Pete Maclean
Vol. 8, No. 19

1STCLASS and COURIERS
Commands

Pete Maclean  November 14, 1989 (Utilities)


Purpose: 1STCLASS helps you manage your MCI mail as well as send and receive
         ASCII and/or binary files. It requires the use of COURIERS, a 1.5KB
         TSR serial port driver program, and a customized script file,
         1STCLASS.CSF.

Format:    COURIERS
    1STCLASS

Remarks: Troubleshooting Tips: If MCI finds faults with a message 1STCLASS
         uploads, an explanation will be displayed. Such diagnostics are not
         written to 1STCLASS.IN but, if you lose the display, you can always
         find it in MAIL.LOG.

     The most common problem is misformatted envelopes.  For a message to
         be delivered, the subscriber must be exactly identified.  If you
         address a message to a name that's not unique, the IDs of all
         subscribers with the name are listed:

     At least one problem with envelope
     608 More than 1 MCI Mail user matches recipient information
     MCI ID   Name         Organization       Location
     000-0000 Zoltan Shah  Whizzo Chocolate   New York, NY
     111-1111 Zoltan Shah  Sunshine Desserts  Fresno, CA

        Select the right one and edit your message to include the ID.
        Remember that the name should be separated from the ID by a slash,
        as in Zoltan Shah/111-1111.  In fact, an ID alone is a perfectly
        acceptable address.

    If MCI objects to something in the envelope of a message, you may
        receive a repsonse such as:

    At least one problem with envelope
    610 Improper information in the envelope
    SUBJECT:  1STCLASS
    This text is part of the message...

    In this case, the blank line needed to terminate the envelope was
        missing.  Other causes might be a mistyped keyword on an envelope
        line or the appearance of lines in an order that MCI cannot handle.

    Some errors offend MCI so much that it stops responding,
    such as a message with two or more addresses on a line.
    A message may be addressed to any number of people, but each address
        must be on a separate To: or Cc: line.

    And, if you receive either a Checksum error or Malformed data message,
        you can be almost certain that a transmission error has ruined your
        session.  Just try again.

    TIPS FOR USING OUR COURIERS UTILITY

    The general format follows that of BIOS calls. The caller places a
        function code in AH, a COM-port number (1 - 4) in AL and parameters
        as necessary in AX, BX and CX, then executes an INT 14H instruction.
        COURIERS returns result codes in AX.

    Function 80h: Check if COURIERS is loaded. If COURIERS is loaded it
        returns 232 (decimal) in AH; otherwise the BIOS returns some
        indeterminable value. Any program using COURIERS should start by
        verifying that COURIERS is loaded and asking the user to load it if
        not  -- just as 1STCLASS does. (AL is ignored in this case.)

    Function 81h: Check if port is busy. COURIERS returns a code in AH:
        2 means that the port does not exist; 1 means that the port exists
        and another program is using it; 0 means that the port is available.

    COURIERS reports code 1 only if another program is using the port via
        COURIERS' own services. There would be no way to tell with any
        confidence if another program were using a port in some other way.
        1STCLASS skips this nicety and seizes the port it is told to use.

        Function 82h: Configure a port. Before doing any I/O, a program should
        configure the port with this function. The line speed in bits per
        second is passed in BX and CX contains a bit vector of various options.
        Only the low two bits are currently assigned: Bit 0001h tells COURIERS
        to handle input flow control; Bit 0002h tells COURIERS to handle output
        flow control.

    Input flow control means that COURIERS will send Control-Ss and
        Control-Qs to regulate the flow of incoming characters. Output flow
        control means that COURIERS will regulate its character transmission
        according to Control-Ss and Control-Qs that it receives.

    In addition bit 0004h is reserved for requesting COURIERS to operate
        the line under the X.PC protocol. This is not yet implemented.

    When configuring the port, COURIERS sets it to send and receive
        eight-bit characters with one stop bit and no parity. There are
        currently no alternatives.

    Function 83h: Start input. This function provides COURIERS with the
        specifications of an area of memory that COURIERS can use as a
        circular buffer for incoming characters. ES:BX point to the buffer and
        CX contains its length in bytes. If input flow control is requested
        then the buffer should be at least 128 bytes. The largest allowable
        buffer is 65,536 bytes, the size of a memory segment. The address
        provided for the buffer must be such that every byte in it can be
        addressed using the segment provided in ES. COURIERS does not check
        for this, however, and if provided, say, with a buffer address of
        1F1D:F000 and a size of 40,000 it would fail rather horribly.

    After input is initiated with this function, it continues until the
        port is deconfigured (function 8D). It is very important that a program
        deconfigure a port after using it or else COURIERS could be left
        stuffing stray characters into an area of memory being used by another
        program for some completely different purpose. And that could lead to
        horrible bugs.

    Function 84h: Read a character. This function requests that COURIERS
        extract the next character from its input buffer and return it to the
        program. On returning, COURIERS sets the ZF processor flag to indicate
        whether or not input was available. ZF = 1 means that no input was
        available. If ZF = 0 then COURIERS also returns a character in AL
        along with a copy of the status bits read from the COM port in AH.
    Note that there is no way to get COURIERS to wait for incoming data.
        If a program just wants to spin its wheels until a character shows up
        it should invoke this function in a loop until ZF is returned as zero.

    In most cases it is safe to ignore the status bits. The only one that
        might possibly have meaning is the status bit that denotes a framing
        error on the received character. Note, however, that COURIERS adds one
        status bit of its own, the highest or sign bit, to indicate an input
        buffer overflow. If input flow control is turned on and operating
        correctly, and the buffer is sufficiently large, an overflow should
        never occur.

    Function 85h: Flush pending input. COURIERS discards any characters
        waiting to be read from its input buffer.

    Function 86h: Start output. COURIERS initiates the transmission of a
        sequence of characters. ES:BX points to the data and CX contains the
        byte count. COURIERS returns to the calling program once the
        transmission is under way; it does not wait until transmission is
        complete.
    The same caveats about buffer addressing given for the input function
        (84h) apply equally here.

    Function 87h: Output status. COURIERS returns the number of characters
        awaiting transmission in AX. It is only safe to initiate another
        transmission when the returned value is zero. The ZF flag is also set
        to indicate if AX is zero or not.  To wait for completion of a
        transmission a program should call function 86 and then repeatedly
        call 87 until a zero value is returned.

    Function 88h: Abort output. COURIERS terminates any transmission in
        progress.

    Function 89h: Transmit a single character. COURIERS transmits the
        character passed in CL. This function may be called repeatedly with no
        tests or checks between calls. It would be used typically by a program
        such as a terminal emulator.

    Function 8Ah: Send BREAK. COURIERS transmits a BREAK condition for
        approximately 385 milliseconds. Note that COURIERS does not detect
        receipt of a BREAK.

    Function 8Bh:  (Not used).

    Function 8Ch: Set speed. COURIERS resets the speed of the port. The
        caller provides this speed in BX. 1STCLASS uses this function to
        change speeds when a connection is completed at a speed other than
        that for which the modem was primed.

    Function 8Dh: Deconfigure port. COURIERS stops input on the port and
        turns off all interrupts. As discussed above, it is very important
        that a program invoke this function upon completing use of a COM port.
    A summary of the functions with the registers and returned values is
        given in Figure A. --