Q51076: PE Option in OPEN COM Statement Enables Parity Checking

Article: Q51076
Product(s): See article
Version(s): 1.00 1.01 1.02 2.00 2.01 3.00 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S891114-52 docerr B_BasicCom | mspl13_basic
Last Modified: 15-MAR-1990

When opening a communications port (COM1 or COM2) in Microsoft
QuickBASIC or Microsoft BASIC Compiler, the parity is not checked
unless the PE option is specified in the OPEN COM statement.

The PE option must be added under the OPEN COM statement (listed
alphabetically under OPEN) in the following BASIC language references:

1. The QB Advisor on-line Help system for QuickBASIC Version 4.50,
   under the OPEN COM statement

2. Page 297 of "Microsoft QuickBASIC 4.0: BASIC Language Reference"
   manual for Versions 4.00 and 4.00b

3. Page 297 of "Microsoft BASIC Compiler 6.0: BASIC Language
   Reference" for Versions 6.00 and 6.00b for MS OS/2 and MS-DOS

4. Page 241 of "Microsoft BASIC 7.0: BASIC Language Reference" for
   Microsoft PDS Version 7.00 for MS OS/2 and MS-DOS

5. The Microsoft Advisor on-line Help system for QuickBASIC Extended
   Version 7.00, under the OPEN COM statement.

6. Page 375 of "Microsoft QuickBASIC Compiler" Versions 2.0x and 3.00
   manual

The PE option is documented in the "Microsoft GW-BASIC Interpreter:
User's Reference" for Versions 3.20, 3.22, and 3.23, under the OPEN
COM statement.

The PE option enables parity checking during communications. A "Device
I/O error" occurs if the two communicating programs have two different
parities. (Parity can be even, odd, none, space, or mark). For
example, a "Device I/O error" occurs when two programs try to talk to
each other across a serial line using the following two different OPEN
COM statements:

   OPEN "COM1:1200,O,7,2,PE" FOR RANDOM AS #1
and
   OPEN "COM2:1200,E,7,2,PE" FOR RANDOM AS #2

If the PE option is removed from the OPEN COM statements above, no
error occurs.

This information applies to Microsoft QuickBASIC Versions 1.00, 1.01,
2.00, 2.01, 3.00, 4.00, 4.00b, 4.50, to Microsoft BASIC Compiler
Versions 6.00 and 6.00b for MS-DOS, and to Microsoft BASIC PDS Version
7.00 for MS-DOS.

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