Running Windows with DOS 4.0x Windows/286 and Windows/386 will run successfully with PC DOS 4.01 and MS-DOS 4.0x. To ensure optimal performance of Windows, DOS must be properly configured. Issues common to both include: DOS version/Windows version DOS shell Issues specific to Windows/286 include: Memory managers XMA2EMS.SYS (PC-DOS) XMAEM.SYS (PC-DOS) EMM386.SYS (MS-DOS) BUFFERS and FASTOPEN DOS version/Windows version Windows/386 will function correctly with IBM PC-DOS version 4.01 only if certain conditions are met. You must have PC DOS version 4.01. Version 4.0 will not work correctly with Windows/386. You must also be using Windows/386 version 2.1 (files dated 9/7/88) or 2.11. These versions of Windows/386 will also work correctly with MS-DOS 4.0 or higher. Windows 2.03 and Windows/286 versions 2.1 or 2.11 will work with either PC-DOS 4.0 or 4.1 and MS-DOS 4.0 or higher. DOS shell Windows/286 and Windows/386 may be run from the DOS Shell. However, a price is paid in doing so. The DOS Shell uses conventional DOS memory (memory in the first 640K of the computer). This conventional memory, once used by the DOS Shell, is no longer available to Windows. This may result in "out of memory" error messages when using Windows/286. Memory Managers PC-DOS and MS-DOS have memory managers that convert extended memory to LIM 4.0 expanded memory. PC-DOS includes two device drivers called XMA2EMS.SYS and XMAEM.SYS. MS-DOS includes these drivers and another driver named EMM386.SYS. These drivers are used in specific situations and must be configured properly for operation with Windows. XMA2EMS.SYS and XMAEM.SYS The XMA2EMS.SYS and XMAEM.SYS drivers are for use with IBM memory boards. They cannot be used with non-IBM memory boards. The drivers may be used with Windows/286 but should not be used with Windows/386. These drivers work in combination with any of the following memory adapter boards: 1. IBM 2-megabyte Expanded Memory Adapter 2. IBM Personal System/2 80286 Expanded Memory Adapter/A 3. IBM Personal System/2 80286 Memory Expansion Option 4. IBM (or compatible) PS/2 Model 80 or Model 70 with extended memory XMAEM.SYS: The XMAEM.SYS device driver is for use on the IBM PS/2 Model 70 or Model 80. It provides emulation of the 80286 Expanded Memory Adapter/A. It does this by using 80386 memory map registers in conjunction with extended memory. This driver must be used prior to using the XMA2EMS.SYS driver which provides LIM 4.0 expanded memory. XMA2EMS.SYS : This is a device driver that supports the Lotus, Intel, and Microsoft (LIM) Expanded Memory Specification (EMS) 4.0 under MS-DOS Version 4.00. If you are using this driver on a IBM PS/2 Model 70 or Model 80 you must specify the XMAEM.SYS device driver before XMA2EMS.SYS in your CONFIG.SYS file. To properly configure this device driver for your machine, refer to the IBM PC-DOS 4.0 manual. Support Issues: The two major support issues related to the use of Windows/286 and the PC-DOS 4.0 memory managers are EMS pageframe conflicts and use of the Windows SMARTDrive, RAMDrive, and HIMEM.SYS. EMS pageframe conflicts are resolved by carefully reviewing your computer's use of memory. This is best done by using the IBM Reference Setup disk and referring to the documentation that accompanies accessory boards that you may be using. These resources provide the memory addresses of boards such as hard disk driver controllers, tape backup controller cards, connectivity boards, network boards, video display adpater boards, and so on. If these boards are located within the same memory range that is used for the EMS pageframe, you will encounter problems. To resolve these problems you must exclude these addresses from use by the pageframe. Refer to the IBM PC-DOS 4.0 manual for specific information regarding how to do this with the XMAEM.SYS driver. SMARTDrive and RAMDrive may be used with PC-DOS 4.0 if loaded into expanded memory. If either of these utilities precede the IBM memory managers in the CONFIG.SYS file, the computer may not boot or continually reboot each time it reads the CONFIG.SYS file. To properly use these utilities, place them after the IBM memory managers (XMA2EMS.SYS and XMAEM.SYS). They must also be loaded into expanded memory. To place SMARTDrive in expanded memory use the /a switch (refer to page 228 of the Windows User's Guide for additional information). To place RAMDrive in expanded memory use the /a switch also (refer to the file RAMDRIVE.TXT included with the Windows diskettes). The Microsoft extended memory manager, HIMEM.SYS can not be used in conjunction with XMA3EMS.SYS or XMAEM.SYS. It simply will not work due to the proprietary nature of IBM's XMA memory. EMM386.SYS EMM386.SYS is a memory manager that is provided with MS-DOS 4.01. It allows 80386 systems to emulate LIM 4.0 expanded memory. It may be used on any 80386 system that is compatible with the IBM AT standard hardware/software interface. It should not be used on the IBM PS/2 computers or compatibles. To install the EMM386.SYS you must place a command line in the CONFIG.SYS. Refer to the README.TXT file on the MS-DOS 4.0 Operating 2 diskette (5.25") for detailed instructions. Do not use EMM386.SYS with Windows/386. It may only be used in conjunction with Windows/286. Support Issues: EMM386.SYS shares the same support issues as do the IBM memory managers as stated above. However, the approach to these issues is slightly different. EMS pageframe conflicts are usually resolved by the driver. It is capable of detecting addresses between A000 and E000 that are used by adapter boards. If it does not correctly detect these addresses then you may use the X or Mx switches. The X switch is used to exclude a specific memory range. The Mx switch is used to locate the beginning of the 64K pageframe at a specific location. The key to using these switches is knowing the addresses of all adapter cards. This is sometimes easier said than done. Two methods for finding these addresses are: 1.) the documentation for the adapter cards, and 2.) third party utility programs that map memory from A000 to FFFF. SMARTDrive and RAMDrive may be used with WIndows in either extended or expanded memory. If you want to place them in expanded memory then be sure to place them after the EMM386.SYS driver in the CONFIG.SYS. The XMS driver HIMEM.SYS works with the EMM386.SYS driver. However, you should use the HIMEM.SYS driver that is supplied with MS-DOS 4.01. This precaution ensures that you are using the most current HIMEM.SYS. BUFFERS and FASTOPEN PC-DOS and MS-DOS 4.0 are capable of utilizing expanded memory for BUFFERS and FASTOPEN. This capablity will not interfere with the operation of Windows providing that it does not interfere with the EMS pageframe. This is especially important with Windows/386. For instance, assume that you are using PC-DOS 4.0 have used pages P254 and P255 (reserved for use by BUFFERS and FASTOPEN) in conjunction with XMAEM.SYS. If using these pages reduces the number of remaining pages to less than four then Windows/386 will not be able to establish a pageframe.