QEMM and 386MAX: Functionality and Compatibility with CV

The information in this article applies to:

• Microsoft CodeView for MS-DOS, versions 3.0, 3.11, 3.14, 4.0, 4.01, 4.05, and 4.1

SUMMARY

The Quarterdeck Expanded Memory Manager (by Quarterdeck Office Systems), otherwise known as QEMM386, and 386MAX (by Qualitas) are memory managers providing support for expanded and VCPI-extended memory, the High Memory Area (HIMEM), and Upper Memory Blocks for machines using the 80386 or 80486 processor.

Some customers have reported difficulties loading CodeView versions 3.x into extended memory when running under these managers. This article deals with the errors, difficulties, and solutions regarding compatibility issues among CodeView, QEMM, and/or 386MAX.

MORE INFORMATION

The first thing to check is the version of CodeView in use. CodeView version 3.0 is not VCPI (Virtual Control Program Interface) compatible, and therefore cannot be loaded into extended memory when QEMM or 386MAX is resident. If you are using CodeView 3.0, you should upgrade to a later version that is VCPI-compatible.

To make CodeView VCPI compatible, a change was necessary to allow access to the memory manager using that management scheme. Since VCPI is a superset of LIM 4.0, the first thing CodeView does is make a call to the LIM driver to determine if it exists. This call actually attempts to establish a 64K page frame. If this is not possible, CodeView assumes there is no VCPI driver and looks for other methods to load itself and the symbol table.

The most common mistake with QEMM is to use either the FRAME=NONE or the NOEMS switch. In both cases, CodeView can't allocate the 64K EMS page frame it requires. The same problem occurs when using 386MAX with the NOFRAME or EMS=0 switch.

The other switches in QEMM and 386MAX are compatible with CodeView. Care must be taken, however, to ensure that the allocation scheme leaves enough VCPI memory for CodeView.

For example, if QEMM (or 386MAX) is configured so that there are four megabytes (MB) of extended memory available and no expanded memory, and a RAM drive is loaded to take up 3.5 MB, CodeView will not be able to load because there will not be enough available extended memory. Note that this is the simplest case and that there are many options and combinations of options that could cause this type of problem.

The examples below illustrate various command-line options for CodeView, QEMM, and 386MAX along with the resultant output.

Notes:

1. Version 5.10 of QEMM386 and version 5.10 of 386MAX have been used for these examples.

2. 386MAX can a command file (386MAX.PRO) to replace command-line switches. This file contains all the necessary options for 386MAX to load as the user has defined. For purposes of readability, only command-line options will be used in the examples.

3. BLUEMAX is a version of 386MAX that runs on a PS/2 and provides extra capabilities for that platform. For the purposes of this article, BLUEMAX and 386MAX can be considered identical.

4. Only one memory manager should be present at any one time. These examples contain the command line and results for both QEMM and 386MAX for the purpose of seeing the result of what each line contains.

5. All of these examples assume that there is enough expanded or extended memory to completely load CodeView and the entire application program. If not, be aware that CodeView will not use disk overlays to load into conventional memory if it was able to partially load into any area above the 640K DOS boundary. If an "Out of Memory" error occurs, a common solution is to use the CVPACK.EXE utility included with the compiler.

CV1301 Error: /X: CPU in protected or virtual mode

   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys NOEMS
   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys FRAME=NONE
   CONFIG.SYS with 386MAX -> device=c:\386max\386max.sys EMS=0
   command line           -> cv /x test.exe

CV1304 Error: /E: EMM driver not loaded

   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys NOEMS
   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys FRAME=NONE
   CONFIG.SYS with 386MAX -> device=c:\386max\386max.sys EMS=0
   command line           -> cv /e test.exe

CodeView hang at load time

   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys FORCEEMS
   CONFIG.SYS with 386MAX -> device=c:\386max\386max.sys NOFRAME
   command line           -> cv {/x | /e | /d} test.exe

CodeView successfully loaded into extended memory

   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys
   CONFIG.SYS with 386MAX -> device=c:\386max\386max.sys
   command line           -> cv {/x} test.exe

CodeView successfully loaded into expanded memory

   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys
   CONFIG.SYS with 386MAX -> device=c:\386max\386max.sys
   command line           -> cv /e test.exe

   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys NOEMS
   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys FRAME=NONE
   CONFIG.SYS with 386MAX -> device=c:\386max\386max.sys EMS=0
   command line           -> cv test.exe

   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys
   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys NOEMS
   CONFIG.SYS with QEMM   -> device=c:\qemm\qemm386.sys FRAME=NONE
   CONFIG.SYS with 386MAX -> device=c:\386max\386max.sys
   CONFIG.SYS with 386MAX -> device=c:\386max\386max.sys EMS=0
   command line           -> cv /d test.exe