Understanding Windows 95 memory- In previous versions of windows and under DOS each of these memory areas played a critical role in the execution of programs (Conventional,
Upper, High, Extended, Expanded, Virtual,) Under Win3.1 and DOS memory was accessed be using a segmented memory model, (16 bit memory) The drawback to this is you can only access 64k of memory at a time, or in 64k blocks. In win95 several of these types of memory are no longer important. Win95 removes that barrier by using memory addressing capabilities that has been available in the CPU since the introduction of the 80386, this memory scheme views memory in a linear fashion, meaning that it is treated physically. To do this Win95 uses 32-bit address register. Thus, Win95 uses 32-bit memory addressing, which allows up to 4 gigs of memory to be addressed directly, without resorting to memory segments and offsets. This change in memory models could be accomplished only by doing away with DOS, which historically has been the limiting factor. The benefit of this change is that programs written for Win95, (using 32-bit addressing), can operate faster and more efficiently, there is less overhead in performing addressing manipulations. Because memory is now treated in a linear fashion, historical constraints associated with conventional, upper, and high memory are done away with. Instead, you have only "ram" and "virtual memory" or hard drive. The new memory manager in the Win95 kernel is charged with keeping things straight. It assigns memory areas to each procedure being executed and the rest of memory is hidden from that procedure This feature provides greater security and stability for both programs and the operating system To sum it up Win95 has completely wiped out the historical 640k barrier that has plagued earlier versions of PC operating systems. The only reason there is the auto.exe and CONFIG.sys is for some dos programs that might need a special configuration and or hardware that Win95 doesn't recognize and you need to load special drivers for them.
Not just DOS games but there are business apps that might benefit from an optimal memory environment with large amounts of conventional memory (the first 640k of addressable memory). Win95 should be able to support these apps by a combination of features. First and foremost, Win95 assigns each and any DOS apps to their own private (unshared) memory spaces and makes available up to 4 gigabytes of virtual addresses. Each DOS app thinks that it has the whole system to itself with incredible amounts of resources. Win95 insulates the app from all other processes, even other apps running concurrently. If no special 16-bit drivers are needed, Win95 also loads all 32-bit drivers “high” into a separate memory space.
This applies to Windowed DOS (“Dos in a Box”) only. Re-booting to DOS will normally retain Win95’s memory management but require 16-bit drivers for peripherals (like the mouse and CD-ROM) and booting directly to DOS is plain DOS without any extended memory managers or drivers.
IO.SYS file Explained- Windows 95 uses a new system file, IO.SYS, which replaces the MS-DOS system files (IO.SYS and MSDOS.SYS). This real-mode operating system file contains the information needed to start the computer. Your computer no longer needs CONFIG.SYS and AUTOEXEC.BAT to start the Windows 95 operating system (although these files are preserved for backward compatibility with certain applications and drivers). Note (The Windows 95 IO.SYS file is automatically renamed to WINBOOT.SYS if you start the computer using your previous operating system.) The drivers loaded by default in IO.SYS include the following, if these files are found on the hard disk: •HIMEM.SYS •IFSHLP.SYS •SETVER.EXE •DBLSPACE.BIN or DRVSPACE.BIN. Most of the common functionality provided by the various CONFIG.SYS file entries are now provided by default in IO.SYS. The following lists the common entries in CONFIG.SYS that are now incorporated into IO.SYS for Windows 95.CONFIG.SYS Settings Incorporated in Windows 95 IO.SYS
>dos=high Specifies that MS-DOS should be loaded in the high memory area (HMA). Also, the umb value is included if EMM386 is loaded from CONFIG.SYS. (IO.SYS does not load EMM386.) himem.sys Enables access to the HMA. This line loads and runs the real-mode Memory Manager. HIMEM.SYS is loaded by default in Windows 95. >ifshlp.sys Installable File System Helper, which loads device drivers. This allows the system to make file system calls. Until this is loaded, only the minimal file system from IO.SYS is used. After this point, the full file system is available. setver.exe Optional TSR-type device. It is included for compatibility reasons. Some MS-DOS-based applications require a specific version of MS-DOS to be running. This file responds to applications that query for the version number and sets the version number required. >files= Specifies the number of file handle buffers to create. This is specifically for files opened using MS-DOS calls and is not required by Windows 95. It is included for compatibility with older applications. The default value is 60. >lastdrive= Specifies the last drive letter available for assignment. This is not required for Windows 95 but is included for compatibility with older applications. If Windows 95 Setup finds this entry, it is moved to the Registry. The default value is z. >buffers= Specifies the number of file buffers to create. This is specifically for applications using IO.SYS calls and is not required by Windows 95. The default value is 30.
>stacks= Specifies the number and size of stack frames. This is not required for Windows 95 but is included for compatibility with older applications. The default value is 9,256. >shell= command.com Indicates what command process to use. By default, the /p switch is included to indicate that the command process is permanent and should not be unloaded. If the /p switch is not specified, AUTOEXEC.BAT is not processed and the command process can be unloaded when quitting the operating system. >fcbs= Specifies the number of file control blocks that can be open at the same time. You should use a fcbs= line in CONFIG.SYS only if you have an older program that requires such a setting. The default value is 4.
To override default values in Windows 95 IO.SYS
•Place an entry in CONFIG.SYS with the value you want.
The values in IO.SYS cannot be edited. If CONFIG.SYS contains switches or other parameters for any of the drivers or settings created by IO.SYS, the CONFIG.SYS entries override the IO.SYS defaults. Entries for files=, buffers=, and stacks= must be set in CONFIG.SYS to at least the default values in IO.SYS.
Note IO.SYS does not load EMM386.EXE. If any of your applications requires expanded memory or loads data into the high memory area, EMM386 must be loaded in CONFIG.SYS.
This is a quote from the Win95 Resources guide.
"Windows 95 uses a new system file, IO.SYS, which replaces the MS-DOS system files (IO.SYS and MSDOS.SYS). This real-mode operating system file contains the information needed to start the computer. Your computer no longer needs CONFIG.SYS and AUTOEXEC.BAT to start the Windows 95 operating system (although these files are preserved for backward compatibility with certain applications and drivers)." The Win95 IO.SYS file is automatically renamed to WINBOOT.SYS if you start the computer using another operating system.
"Windows 95 also creates a hidden, read-only system file named MSDOS.SYS in the root of the computer's boot drive. This file contains important paths used to locate other Windows files, including the Registry. MSDOS.SYS also supports an [Options] section, which you can add to tailor the startup process." This file is a simple text file.
When you install Win95 onto a "clean" hard drive, no traces of on older DOS are left on this drive, the only version of DOS that is available with such an installation is the Windows 95 DOS, a Virtual DOS."
Msdos.sys file- Go straight to Microsoft to read about this, this page is already to big.
http://support.microsoft.com/support/kb/articles/q118/5/79.asp
