Article ID: 37307
This article was previously published under Q37307
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You will encounter some limitations if you wish to conditionally load QBHERC.COM or MSHERC.COM from within a QuickBasic program.
The only way to invoke QBHERC.COM or MSHERC.COM from within a QuickBasic program is with the SHELL statement. QBHERC.COM and MSHERC.COM are terminate-and-stay resident (TSR) graphics drivers. TSR programs will fragment MS-DOS memory when loaded with the SHELL statement. You can only unfragment the memory by rebooting the computer. Fragmentation can drastically reduce the memory available to subsequent programs run in MS-DOS. This fragmentation problem can be serious, and it is best to avoid SHELLing to QBHERC.COM or MSHERC.COM or any TSR program.
Note that the Basic run-time routines must know at initialization time (that is, when the program is started) whether or not QBHERC.COM or MSHERC.COM has been loaded. This means a program (or batch file) that loads QBHERC.COM or MSHERC.COM must RUN or CHAIN (or invoke) the .EXE program that will use Hercules graphics.
This information applies to Microsoft QuickBasic 4.00, 4.00b, and 4.50, to Microsoft Basic Compiler Versions 6.00 and 6.00b, and to Microsoft Basic PDS Version 7.00 for MS-DOS and MS OS/2.
The following is a possible scenario for conditionally executing QBHERC.COM or MSHERC.COM:
Hercules support was introduced in QuickBasic Version 4.00. For more information, please see the README.DOC file for QuickBasic Versions 4.00 and 4.00b.
Article ID: 37307 - Last Review: February 28, 2014 - Revision: 1.2
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