Much confusion exists as to whether Chicago will “obsolete” DOS utilities and programs, particularly memory management. Microsoft’s operating system, code-named Chicago, and recently renamed to Windows 95, is a revolutionary step, but it’s still MS-DOS and memory management problems will still exist for a while.
Contrary to what Microsoft would have the world believe, it will probably still be necessary to loading many device drivers the way MS-DOS does now in CONFIG.SYS (and sometimes in AUTOEXEC.BAT) and go through the hassle of figuring out how and where to load them high. Windows 95 may have Virtual Device Drivers (VxDs) which provide much of the MS-DOS driver functionality and VxDs do not require conventional memory, but Newsbytes has learned VxDs will not provide much memory relief because so much of the hardware and software functionality found in today’s PCs won’t have VxD counterparts available when Windows 95 ships.
Furthermore, sources at Helix told Newsbytes VxDs, which substitute for DOS devices such as compression, CD-ROM, or network drivers, will still need to have DOS counterparts in conventional memory for compatibility with DOS applications and for use when users run “Exclusive” DOS sessions.
Newsbytes has learned Windows 95′s boot sequence boots MS-DOS, which then loads Windows using a “Win” command that is built into the AUTOEXEC.BAT. If the Windows (as opposed to DOS) component of Windows 95 is only accessible through a device driver (as on compressed drives, network drives, or secondary hard drives) then the DOS-based version of the device must be loaded into conventional memory even if a VxD provides the same functionality once Windows loads.
Also in question is whether or not the need for DOS memory will diminish because Windows 95 has DOS built into Windows in 32-bit mode.
Technical sources at the leading publishers of third party memory managers told Newsbytes moving DOS to protected mode will not affect DOS applications at all because DOS itself is not causing memory problems. Rather, it is the DOS application’s need for conventional (below 1MB) memory, together with the large variety of drivers that most users have loaded, that causes memory constraints. The third party memory managers create more memory below 1MB than Microsoft’s memory manager.
Another issue raised by third party memory managers is that existing Windows applications will continue to require DOS memory until they are updated to take advantage of new DOS APIs that don’t require “Global DOS Memory” under Windows.
Microsoft says DOS drivers will not be needed by Windows 95 anymore, and they will slow things if they are used. Newsbytes has learned many will continue to be needed until there are suitable VxDs to replace them. The first wave may end up being slower than their DOS-based counterparts which have been optimized for performance and reliability.
Microsoft is predicting users will never need to run “Exclusive” DOS sessions because even the popular arcade game “Doom” runs in a DOS box. But many MS-DOS programs, particularly vertical market applications, don’t run in a multitasking environments, and probably never will. These programs (such as games and process control software) either require real-time response or, by design, can’t handle having the surrounding environment change without their knowledge. Such programs will never run well in Windows and will require “Exclusive” DOS use, which means memory management. This is why most users still exit Windows several times a day. It’s also why Microsoft saw fit to add multiple configuration support in (inside CONFIG.SYS)in native MS-DOS.
Until users are exclusively using Win32/Windows 95 applications, and until all DOS drivers are converted into VxDs, Windows 95 will still need memory management (as did DOS 5 and 6 and Windows 3.1). That’s why products like Netroom, QEMM, and 386Max will continue to be useful to PC users long after Windows 95 starts shipping.