Programmer's WorkBench 2.x and Extended Memory

ID: Q85513

2.00 2.10.49 MS-DOS kbtool

The information in this article applies to:

• Microsoft Programmer's Workbench for MS-DOS, versions 2.0 and 2.10.49

SUMMARY

The Programmer's WorkBench (PWB) version 2.0 that comes with Microsoft C/C++ version 7.0 will attempt to use extended memory if it is available (extended memory in the context of this article is meant to include both XMS [extended] and EMS [expanded] memory). Although it is not required, the availability of extended memory increases the speed at which PWB can operate.

MORE INFORMATION

PWB attempts to utilize extended memory in three ways:

• Virtual memory (VM)--PWB puts data such as build information and file data in virtual memory. VM can be accessed only from conventional memory (near or far memory below 640K). If a VM request is made and there is no available conventional memory, then any unused VM is swapped to an extended memory cache. When the extended memory cache is filled up, or if there is no extended memory, then the cache is moved to the disk.
• The VM files are deleted when PWB is exited in normal fashion. If the system hangs or if a situation arises such that PWB cannot be exited correctly, you may see files on your disk that follow this naming convention: PWB*.VMM. Deleting these files while not in a PWB session will not corrupt the system. Do not delete these files during a PWB session, however, because PWB may be using them.
• When PWB spawns another program (the compiler, linker, CodeView, or the application being developed), PWB attempts to save an image of itself in extended memory. Again, if there is not enough extended memory, or there is no extended memory, PWB saves the image to disk.
• PWB was built with MOVE (Microsoft Overlaid Virtual Environment), technology which utilizes extended memory as a cache for its overlays. If there is not enough extended memory, or there is no extended memory, overlays are read from disk.

  Extended memory increases the operating speed of PWB, but it does not improve functionality. For example, extended memory does not allow more extensions to be loaded. The best way to ensure smooth operation of PWB is to increase the amount of available conventional memory.

Last Reviewed: July 18, 1997