Microsoft KB Archive/32473

= /C No Effect on Communications Receive Buffer in CHAINed Prog =

Article ID: 32473

Article Last Modified on 11/21/2006

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APPLIES TO


 * Microsoft QuickBasic 2.01

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This article was previously published under Q32473



SUMMARY
Programs can be given a new communications device receive buffer size using the /C:size option at compile time. This option sets up a new receive buffer size as specified, except for the program PROG2.EXE, when all of the following conditions are true:


 * 1) PROG2.EXE was compiled with the /C:size option.
 * 2) PROG1.EXE CHAINs to PROG2.EXE with the CHAIN statement.
 * 3) The CHAINing program (PROG1.EXE) was NOT compiled with the /C option.
 * 4) The programs (PROG1.EXE and PROG2.EXE) were both compiled with the &quot;BRUN&quot; run-time module (NOT compiled with /O).

Thus, if you plan to change the default communications receive buffer size with the /C option in a CHAINed program (such as PROG2.EXE), you must compile the CHAINing program (PROG1.EXE) with the same /C option.

The communications buffer is set when PROG1.EXE (the CHAINing program) and the BRUN library are loaded into memory at run time. During a CHAIN, the BRUN run-time module is not reloaded, so the buffer is not reset to the /C size that you specified for the CHAINed program (PROG2.EXE).

This information applies to Microsoft QuickBasic Versions 2.00, 2.01, 3.00, 4.00, 4.00b and 4.50, and to Microsoft Basic Compiler Versions 6.00 and 6.00b for MS-DOS and OS/2.

An alternative, independent of the /C compile-time option, is to use the RB option to set the receive buffer size at run time in the OPEN COM statement in PROG2.EXE. The RB option to set the receive buffer size in the OPEN COM statement is introduced in QuickBasic 4.00 and later versions, and is not available in QuickBasic 2.00, 2.01, and 3.00. Using the RB option lets a CHAINed program (PROG2.EXE) set the receive buffer size independent of the settings in the CHAINing program (PROG1.EXE).

Additional query words: QuickBas BasicCom

Keywords: KB32473

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