PC Hardware Overview

The parts will change.

DOS STARTUP (ver 3.3+)

• For a partitioned drive, the master boot record is loaded first. It contains a small program to load and execute the partition that is marked as the active partition (C:, containing DOS).
• The DOS loader in the boot sector (of either the diskette or active partiton) loads IO.SYS, which must be the first file in the root directory of the startup drive, and which must be stored in contiguous sectors. IO.SYS examines the system and installs the internal DOS device drivers, including drivers for all disk drives. In assigning drive letters from C: through Z:, the following rules are used:
  • All non-DOS partitions are completely ignored. This includes OS/2's hidden DOS partitions.
  • The first active primary partition on the first harddisk will always be called `C:'. DOS expects to be booted from this partition.
  • Each active primary DOS partition on each subsequent drive is assigned the next drive letter, even if it is not the first primary DOS partition. If a drive has no active (DOS) partition, its first primary DOS partition is assigned a drive letter. If no primary DOS partition exists on the drive, no drive letter is assigned in this stage.
  • All extended partitions on all subsequent drives are assigned drive letters in turn.
  • Lastly, all remaining primary partitions on all subsequent drives are assigned drive letters in turn.
• MSDOS.SYS is loaded. It contains the majority of the MSDOS kernel. It must be the second file in the root directory and its sectors must be contigous.
• Some interrupt handlers are set up.
  • INT 21h - DOS kernel
  • INT 28h - DOS idle poll
  • INT 29h - DOS fast screen output
  Other interrupt numbers from 0Fh - 3Fh without any specific purpose is initialized to point to an IRET instruction. Certain DOS structures are set up, which may be altered or expanded.
• DOS versions 6.x may load a special 'pre-loadable' device driver at this stage. The technology responsible for this has apparently been patented by Microsoft; thus no-one else may write a pre-loading driver without a license from Microsoft.
• The CONFIG.SYS file is processed. The CONFIG.SYS file allows various operational settings to be made and further device drivers to load. In later versions of DOS it also allows memory resident programs to be loaded, however they are always loaded after all device drivers.
• The command interpreter, COMMAND.COM is loaded. It sets up the standard devices for itself, and passes these on to any programs it spawns.

DOS PROGRAM STARTUP

• Environment variable storage area is allocated. The environment variables are copied to it, each in the form of a stringz 'name=value'; the final variable is followed by a further nul byte, a WORD value (always 1; meant to signify the nuber of strings following) and the full path including drive and filename of the executed (this) program.
• Program memory area is allocated
• first 100h bytes becomes the 'Program Segment Prefix' (PSP). The command line arguments are stored in the PSP and the first two arguments are translated as if they were filenames into the two default file control blocks (FCBs) within the PSP.
• the program itself is loaded directly after the PSP. The memory block in which the PSP is located is extended to accomodate the program (a second memory block is not allocated).
• Various file handles are available (have been inherited from parent process) including:

  Handle name	Handle value
  STDIN (Standard Input)	0
  STDOUT (Standard Output)	1
  STDERR (Error output)	2
  AUX (Auxillary, usually COM1)	3
  PRN (Printer, usually LPT1)	4

• The following interrupt vectors are set: Interrupt 22h (terminate address), Interrupt 23h (Ctrl-Break handler) and Interrupt 24h (Critical error handler) to default DOS handlers.
• Data Transfer Area (DTA) is set to 80h in the PSP
• Command line arguments are placed at address 80h exactly as they appeared on the command line. 80h itself is a byte giving the length of the command line. Pipes and redirections from the command line are not available; to determine if redirection is occuring, a program must determine what file/device is assosciated with the various standard handles.
• DS and ES are set to the PSP segment address; for COM files CS and SS are also set to this address. EXE files have a header which specifies values for CS and SS.
• SP is for COM files set to the top of the memory block allocated for the program, + 1 (usually this gives it a value of 0), and then the immediate value '0' (a WORD) is pushed onto the stack (placing it at the top of the memory block. This allows a RET instruction to terminate the program). For EXE files SP is set from the header.
• code execution begins at CS:100h for COM files. For EXE files, starting address is set by the header. Registers usually contain 0, but it is safest not to assume any value.

DOS Information

Contents

• History
• Understanding DOS
  • Default device allocation
  • Disk organization
  • Raw and cooked mode
  • DOS interface to applications
• Internal operation and structures
• Programs under DOS

Intel is a registered trademark of Intel Corporation.
IBM and PC-DOS are registered trademarks of International Business Machines.
CP/M is a registered trademark of Digital Research

History

There are some rumours that there was a communication breakdown between IBM and IDR (Intergalactic Digital Research, the company who owned the rights for CP/M, now known by the less austentatious name of Digital Research), but whatever the reason, the system finally licensed was the then-small Microsoft's 'MS-DOS', which was itself adapted from 86-DOS, also known as 'QDOS' - for 'Quick and Dirty Operating System'.

Because of bugs found in the early MSDOS, IBM wrote their own version of DOS, designed to be compatible with Microsoft's specification, which they called PCDOS (presumably standing for Personal Computer Disk Operating System). To this day the two DOS's are marketed seperately by their respective companies, though the Microsoft product is by far the most popular.

Since those early times DOS has developed rather significantly. Other companies including Digital Research began to market different versions of DOS; DOS version numbers increased and DOS became more complex and powerful. The most significant advancement was version 2.0 which was designed to allow the used of hard drives, and then DOS 3.0 (3.3 by the time the bugs were removed) which had built-in support for networking. Further enhancements were also made but more and more rarely were they an internal part of DOS.

Further reference: 'DOSREF 3.3' by Dave Williams (disk based text)

Understanding DOS: How it works, how it is organized

However, in a sense, a fourth layer exists between the BIOS and DOS level (or in some cases directly between DOS and the hardware). This layer is comprised of device drivers. Device drivers are special programs which interface DOS to a hardware device (either directly or through the device).

Device drivers can be classified in various ways. The biggest distinction is between 'block devices' and 'character devices'. Block devices are devices which operate on blocks of data and are represented in DOS as disk drives, accessible through a drive letter. Character devices on the other hand will accept as little as a single byte at a time to operate on; character devices include the video screen and printers.

Some hardware devices can not be classified as either, however; an example is the mouse. Although the mouse driver could be implemented as a character device driver, this would prove inefficient and cumbersome, and mouse drivers generally do not adhere to the DOS device driver standard but rather provide functions to programs through a seperate interface.

Also, be aware that some devices which appear as block devices (in the sense that they are accessed through a drive letter) are actually using a special network interface that DOS provides (the 'redirector interface'). The allocation of physical space on such devices is allocated not by DOS but by the device driver itself, or by the hardware or network which the driver interfaces with. Such devices include network drives and CD-ROM drives. As a matter of fact, CD-ROMS are seperated even by a further layer - the MSCDEX program (Microsoft CD extensions). The redirector interface is not well documented; many references neglect to even mention it.

Note as well that a single block device driver can control more than one block device, and a single device driver file can contain more than one driver. This effectively allows one device driver to be responsible for a number of devices.

In summary, there are three types of drive devices: 'local' block devices, 'remote' network drives, and local drives using the network interface. There are also two other types of drivers: character devices and 'alternate' devices such as the mouse.

Device allocation

The internal block devices are A: and B: - the floppy drives; if no B: exists, then B: becomes a second way of referencing the first floppy. Normally, when B: is accessed after A:, the DOS internal driver displays a message 'to insert a diskette for drive B:', and when when A: is accessed after that, the same occurs 'for drive A:'. This can be used to emulate the presence of two floppy drives. C: and D: refer to the first and second hard disk drive respectively. If no hard drives exist, C: and D: will not be automatically created; if a second HD does not exist, C: but not D: will be created. No emulation of a second HD is performed.

Standard character drivers (except for NUL) can easily be replaced by installing a new driver with the same name. The character devices are:

NUL: This device simply ignores all output and gives no input. It is mainly used with re-direction on the DOS command line to suppress a program's output. NUL is the only character device driver which cannot be replaced.

COM1 - 4 (eg COM1, COM2...): The computer's serial ports. Interestingly enough, if there are less than four devices, four driver interfaces are still supported. The extras act just like the NUL driver.

LPT1 - 3 (eg LPT1, LPT2...): The computer's parallel ports. The behaviour here is the same as for the COMx devices.

PRN: An alias for LPT1

AUX: An alias for COM1

CON: Any output sent to CON will (usually) go to the screen; any input will come from the keyboard (the keys the user has pressed). This device works by calling the BIOS keyboard and video functions. DOS checks the character in the devices (keyboard's) input buffer on many function calls (depending on the value of BREAK, see the discussion of control variables in Programs Under DOS) and takes action on certain combinations (see below). Also, this device intercepts INT 1Bh calls (made by BIOS when the CTRL-BREAK key combination is pressed) and returns CTRL-C as the next character if a CTRL-BREAK has been detected.

$CLOCK: The clock device is used to control the time-keeping clock on systems equipped with such a device. The $CLOCK device uses a special format for input and output, as shown below:

Disk Organization

In essence, all a block device needs to be able to do is to follow instructions from DOS to read from and write to certain sectors (or clusters as they are called, as a device may use a block size of several physical sectors).

Each block device may have a certain number of 'reserved sectors' which DOS does not use. For a floppy drive, this contains the boot sector (which contains code executed if the computer is 'booted from the floppy' - usually this is done by simply resetting the computer with the floppy in the drive). Hard drives also have a 'master partition table' although this is usually made completely invisible to DOS (it is not one of the reserved sectors).

There are also a number of FATs (usually 2). a FAT is a 'file allocation table' and contains information about which clusters are being used by which files. All FATs are modified one after the other so all should be identical. If one FAT is inadvertantly destroyed, another can be used to replace it, with minimal loss of information.

Following the FATs is the root directory space. Because this space is a fixed size, there is a practical limit to the number of root directory entries. The volume label of a drive is also stored as a root directory entry. Each entry contains a file name (or volume name), date and time which the file was last altered, file attributes (volume label, directory, hidden, read-only, system and archive), size, and first cluster occupied by the file- subsequent clusters can be found by examining the FAT.

The volume label attribute describes the entry as being a volume label rather than a file. The directory attribute specifies the entry is for a directory rather than a file (though a directory is stored in the same way as a file; the format is similar to that of the root directory itself). The hidden attribute is used to signal to programs that the file should not be listed in a normal directory listing, and not interpreted as being part of a file specification that uses wild cards. The read-only attribute causes DOS to give error messages to programs attempting to write to, destroy or alter the file (although the attributes may still be altered, in order to be able to remove the read-only attribute if alteration is necessary). The system attribute has in essence the same meaning as the 'hidden' attribute; system files are considered crucial in the operation of the system, and should generally not be moved from their location on disk. The archive attribute is set by DOS whenever a file is changed, as is the file date and time (accurate to two seconds).

Raw and cooked modes, STDIN and STDOUT

Cooked mode means that on any 'input with echo' performed on the device, if a control character is input, it is echoed as double character, the first being a caret (^) and the second being the appropriate alphabetical character. Also, any output is scanned for CTRL-Z and if a CTRL-Z is found, the output block is terminated (that is, output only continues up until the CTRL-Z is reached, the rest of the output block is discarded; further output continues when the next output block is sent). Input from the device is also scanned: If the first character of a buffered read is CTRL-Z, no input is returned until the next read is made. However a CTRL-Z embedded within a block of input is not treated specially (tests made in DOS version 6.22)

All character devices may be flagged as being STDIN and/or STDOUT devices. Standard input devices are treated specially by DOS, in that when a buffered input occurs, the user has a chance to edit the line of input using the backspace key to delete the previous character. All characters input in this way are echoed as output to the device (so that the user can see what they are typing or inputting), the backspace key is converted to 'backspace-space-backspace' (so that it overwrites the character which would otherwise be left visible for this purpose). STDOUT only has special purpose when printer echo is turned on (see DOS interface to programs).

The DOS interface

Most input/output is performed using a 'handle' which is a numerical value indicating to DOS upon what the operation in question is to be performed. The five standard devices are 'open' and assigned a handle automatically; these are STDIN: 0, STDOUT: 1, STDERR: 2, STDAUX: 3, STPRN: 4. Interestingly enough any device can be assigned as a STDIN or STDOUT device, though the STDIN and STDOUT of a program by default refers to the CON device. STDIN (standard input) is usually assigned to the CON device and thus the computer's keyboard, STDOUT is usually also assigned to the CON device and so the video screen (both STDOUT and STDIN can be redirected on the DOS command line using the COMMAND.COM interpreter), STDAUX is usually AUX, STDPRN is usually PRN, and STDERR is also a reference to CON (for the purpose of displaying messages that must be seen even if output has been redirected). Note that a program refers to a standard device by number and not by name.

Any other I/O requires that the file or device be 'opened' first. The open request is made by the application using the Int 21h interface, and DOS returns (assuming no error occurs) a handle that the application can use in subsequent requests (known as 'calls'). When the application is finished with the file or device, the handle is 'closed' using another DOS call.

* DOS will only directly access the first 640 kilobytes of memory. Enhancements which allow the use of UMBs (upper memory blocks) allow access to a full megabyte of memory. Further memory is considered 'expanded' or 'extended' according to the way in which it is accessed, and can be allocated or deallocated using the appropriate interface for the type. This is beyond the scope of this document.

Internal Operation and Structures

The 'System File Tables' (SFTs) contain information about all the presently open files. The SFTs are stored in a chain so that in knowing the address of the first, the address of subsequent tables can be found.

The 'Current Directory Structures' maintain information about the current directory of each logical drive. These structures can be manipulated to create redirection (whereby one drive unit actually references a different drive, or even a subdirectory of another drive), including network redirection. This is how the DOS SUBST command works.

'File Control Blocks' (FCBs) are an obselete method of file access, now replaced with the file handle functions. DOS still supports the FCB functions to maintain compatibility with previous versions, but now all FCB files also have an entry in the SFTs. The FCB functions are really just 'layered over' the handle functions.

'Memory Control Blocks' (MCBs) are headers at the start of each allocated and free memory block, giving information about the size of the block as well as information such as what program 'owns' the block (that is, what application requested the allocation of the block). For Upper Memory Blocks (those beyond the 640KB barrier), the corresponding control blocks are known as 'UMCBs'.

'Program Segment Prefixes' or PSPs are structures containing information local to specific programs. Every running program should have a PSP. When a program exits, the PSP is destroyed and the memory it occupies is freed. The main use of PSPs is to hold a 'local file table' which actually contains indexes into the SFTs.

In most applications, there will be no need to manipulate these structures directly; DOS does everything necessary when requested to do so (for instance, when a file is opened by an application, the application's PSP file table is updated and a new entry (if necessary) is created in the SFTs.

Programs under DOS

Then there are application programs (which can also take the form of utilities, games etc). These programs are stored in 'executable files' on a DOS drive. Programs can be loaded in one of two ways: By DOS at boot time (if the program is the 'shell'; the default shell is of course 'COMMAND.COM', the command-line interpreter), or by starting them from within another program (for instance, starting a program by typing its name on the command line).

All DOS programs have their own data information block called a 'Program Segment Prefix' (PSP). The PSP contains information about the currently running program, including the return address to the parent program (or 'parent process': The process which caused the 'child' process to execute), and information about what files the program has opened (in the form of indexes into the system file table). The program references files through an index into its own internal table; these local indexes are also known as 'file handles'.

DOS programs also have an 'environment' (or 'environment table', or 'environment string table') which is a number of named strings of text of any value. Any program inherits an exacr copy of its parent's environment (except of course the shell, which has no parent). The environment variables as they are called are used to keep track of information and provide information that is easily accessible to all programs. Environment variables and their values have no direct meaning to the DOS kernel, but many DOS utilities and programs make use of them - for example, the command interpreter:

• 'PATH' is used to keep track of directories to be searched when a program is started
• 'COMSPEC' is used to keep track of where the interpreters executable is stored

Programs also have access to certain global DOS variables. These are the 'Verify' switch (which when 'on' causes DOS to verify any write operation is performed correctly, by reading the information back from the device and comparing it with what was supposed to be written) and the 'Break' switch (which controls how often checking for Control-C from standard input is performed). DOS also keeps a 'machine name' which is generally used only in networking systems to identify a node of the network.

DOS allows its programs a great deal of freedom. As DOS is a real mode operating system, direct hardware manipulation (using IO ports or BIOS) is possible, though wherever possible, the use of DOS functions is recommended. The use of direct hardware programming and BIOS gives much flexibility to DOS programs.

DOS Executable formats

Some .COM and .EXE files are simply 'memory images'. That is, the file is simply a sequence of bytes to be loaded at any segment address at offset 100h (to allow for the PSP), with execution beginning at (segment):0100h. These programs may never exceed 64KB in size, and are always allocated at least 64KB of memory (they are, in fact, allocated all of the memory block into which they are loaded).

Device driver (.SYS) files are also (generally) memory images, but follow a special format reserved for device drivers. Device driver files may also take the .EXE format, in which case they can be loaded as a normal DOS program as well as a driver (in which case the EXE header is ignored; the driver header should immediately follow it). The device-driver format is beyond the scope of this text.

Program files may take another format which allows programs to have several logical segments (and thus exceed 64KB in size). All such executable files (and I stress that both .COM and .EXE files may take this format) begin with a double byte 'signature' within a variable-size header to indicate that they are in fact segmented. This is the ascii equivalent of 'MZ', the initals of Mark Zbikowski, one of the principal designers of DOS. The header (which must be a multiple of 16 byes in length, and is nearly always set at 512 bytes length - for no real reason) contains a 'relocation table' which is a table of segment pointers within the program which must be 'fixed' at load time to point to the correct physical segment, by adding the actual physical segment at which the program was loaded (the segment immediately after the PSP).

Files in this format may also specify a 'minimum' and 'maximum' amounts of memory to allocate. If 'maximum' is greater than the memory available in the block into which the program is being loaded, all the memory in the block will be allocated. If the minimum required memory cannot be allocated, the program will not be executed. If the maximum is less than the amount available, the program will be loaded so that is at the high end of the memory block.

DOS Disk Information

DOS hard drives may be 'partitioned' to form several 'logical drives' (which are normally each assigned their own drive letter by DOS). Only one partition at a time can be marked 'bootable'. The partition table information is contained in the master boot record (the true boot record, "MBR") of the drive, which resides on the first logical sector (of the first track or cylinder on the first head). That first sector also contains the MBR code, which determines the bootable partition and loads the boot sector (first logical sector) of that partition, executing it as if it was itself a boot record (loaded at the same location, registers contain the same values). It is possible to install several different operating systems on one computer in this way, especially if the standard MBR code is replaced in order to allow the bootable partition to be seleced at boot time.

There is a limit of four entries in the master partition table. DOS allows these entries to contain pointers to 'extended partition tables', whose format is exactly the same as for the main partition table except there is no boot code (the space normally reserved for the boot code is empty). All the extended partitions should exist within the space reserved by the extended partition entry - only two of the extended partitions are meant to be used, the first as a normal partition, the second as another extended partition (optional).

The DOS boot sector contains as a first instruction a 'jmp' (code 0EBh for DOS 3.x+) to the real code. The boot sector contains various information about the disk, including a BIOS parameter block, as well as some DOS startup code, which loads (part of) IO.SYS or the equivalent and passes control to it. The exact workings may be DOS specific and version specific.

Any sectors before the boot sector of a logical DOS drive are considered to be 'hidden' sectors. The DOS kernel does not interpret hidden sectors (it is up to the disk device drivers, which are usually internal to DOS anyway, to skip 'hidden' sectors). Normal floppy drives have 0 hidden sectors. Hard drive partitions will have a number reflecting their location on the drive. Note that the whole first head of the first cylinder is (usually) reserved for the partition table, even though it is only the first sector which is actually used.

Following the hidden sectors are 'reserved' sectors usually used only for the boot sector. Following this are the File Allocation Tables (FATs). The FATs should all be identical (there are normally two). They contain a map of cluster usage (the data area sectors are grouped into 'clusters'. The number of sectors per cluster does not vary for any particular disk, and depends on the number of sectors - DOS can only map a certain number of clusters; if there are more sectors than the maximum number of clusters, then more than one sector is assigned to each cluster). The FATs also mark bad clusters, and give the order of clusters for a file.

Following the last FAT is the root directory. The root directory is variable size but must be contiguos (and under DOS cannot normally change size once initiated). The root directory contains information about the files and directories branching from the root directory. All further directories are themselves stored as files, in the same format as the root directory.

Interestingly enough, the volume label for a floppy is usually stored within the boot sector, but the volume label for a hard drive is stored as a root directory entry and the space reserved in the boot sector is left blank with spaces. The DOS 'DIR' command returns the one in the directory if present, or the one in the boot sector if not.

Master boot record format

Partition table entry format

Beginning/ending head/sector/cyinder: In determining the sector/head/track from an absolute sector number, the sector is incremented first (is the least significant portion), then the head, then the track/cylinder (most significant portion). Sector numbers start at 1, head/cylinder numbers start at 0.

Also, the 2 most significant bits of the (10 bit) cylinder number are stored in the 2 most significant bits of the byte at offset 02h/06h. The other bits in this byte form a 6 bit sector number. Thanks to Rick Ondrejicka for pointing out that I had originally missed this :-)

System indicator: 0 = not defined/unknown, 1 = DOS 12-bit FAT, 2-3 = XENIX, 4 = DOS 16 bit FAT with 512 or less bytes/cluster (<32 MB), 5 = Extended DOS partition, 6 = large (bigger than 32MB) DOS partition with 16 bit FAT, >512 bytes/cluster.

DOS Boot Sector

Bytes per sector: Must be an integer power of 2 (eg, 64, 128, 256). Floppy disks are normally 512 bytes/sector; most fixed disks are also 512 bytes/sector.

Total number of sectors: Excludes hidden sectors. If zero in the BPB, the field in the extended boot record information is used and vice versa.

Media descriptor: Used to give an indication of the media (disk) type. Normal values are 0 for an extended DOS partition, 0F0h for a (18 sector/80 track) 1.44MB 3 1/2 inch floppy, 0F8h for a hard drive, 0FDh for a (9 sector/40 track) 360KB 5 1/4 inch floppy (unverified) or a (9 sector/80 track) 720KB 3 1/2 inch (verified) , 0F9h for a (80 track 15 sector) 1.2MB 5 1/4 inch floppy. '0' seems to be the best way to go for anything else. The media descriptor byte doesn't appear to actually mean very much.

FAT

First two entries: Reserved. The first byte of the first entry is also the media descriptor byte.

Further entries: (MAX is 0xffff for 16 bit fats, 0xfff for 12 bit fats)

0	if the cluster is unused (free, available)
(MAX-7) to MAX	Last cluster in file
(MAX-8)	bad cluster
(MAX-15) to (MAX-8)	reserved cluster
Anything else:	Next cluster in file chain (this is the number of the appropriate entry in the FAT table, so #2 is the first non-reserved cluster)

Directory entry format:

Note also that all subdirectories (but not the root directory) contain entries for the '.' (this subdirectory) and '..' (parent directory) directories, as displayed in a normal directory listing.

Offset	Description
0	(11 bytes) file name or (on hard disks) volume label. For file names, the first 8 bytes are the name before the extension (left justified, padded with spaces) and the final 3 bytes are the extension. If the first byte is 0, this entry is invalid and is the last entry. If it is E5h**, the file has been deleted. If it is 5, the first character is actually an 0E5h (but the file has not been deleted).
0Bh	File attributes: bit 0 - read only flag bit 1 - hidden file flag bit 2 - system file flag bit 3 - volume label flag (indicates entry is a volume label) bit 4 - file is a subdirectory (in same format as directory) bit 5 - archive bit (file modified since last backup), set by DOS bit 6 & 7 - reserved
0Ch	(10 bytes) reserved
	Time and date stamp give time of last file modification
16h	(2 bytes) timestamp (bits 0-4 : seconds in two second increments, bits 5-10 : minutes, bits 11-15 : hours [from 0-23])
18h	(2 bytes) datestamp (bits 0-4 : day of month, 5-8 : month, 9-15 : years since 1980)
1Ah	(2 bytes) First cluster of file (2 = first cluster after root dir). A value of 0 is used in 'parent directory' ('..') entries to indicate that the parent is the root directory.
1Ch	(4 bytes) File size in bytes.

 
During time I have assisted quite a lot of PC owners with the setup of their two system files CONFIG.SYS and AUTOEXEC.BAT.  Often when I stand in line in a computer store (I have seldom seen that there isn't a waiting line), I have experienced that a great many of the problems, the customers complains about, are due to improper setup of these two files.  Therefore I hereby pass on some advice about that subject.

Contents:

• Before you begin !
• MS-DOS 7.00 / 7.10 (Windows 95 & 98).
• Windows 95 OSR2 and HIMEM.SYS.
• DOSSTART.BAT (Windows 95 & 98).
• WINSTART.BAT (Windows 95 & 98 and Windows 3.11).
• MS-DOS 6.22 (Windows 3.11).
• PC DOS 7.00 (IBM).
• Windows 3.11.
• More Upper Memory with EMM386.
• Alternative Memory Managers (QEMM386).
• Stacker disk compression.
• Harddisk partitioning.
• Windows 95 OSR2 and FAT32.

Before you begin !

Some of the following is very basic, while some of it is addressed to the experienced PC user.

Before you begin to change the CONFIG.SYS and AUTOEXEC.BAT files, you should do the following:

This will always give you the possibility of starting the computer by inserting the floppy diskette in drive A:, then rebooting the computer.

If there are problems starting the computer, then as from DOS version 6.00 you can press the F5 key, when the screen displays:  Starting "Windows 9x..."  ("Starting MS-DOS...").  This skips the executing of the CONFIG.SYS and AUTOEXEC.BAT files.  Thereafter you can edit the line in one of these two files where the problem occurred.  If instead the F8 key (plus 4 in Windows 9x) is pressed, then the lines in CONFIG.SYS and AUTOEXEC.BAT will be executed one line at a time.  This helps determining where the problems occurs.

MS-DOS 7.00 / 7.10 (Windows 95 & 98)

• Windows 95 has DOS-version 7.00
• Windows 95 OSR2 and Windows 98 has DOS-version 7.10

Under Windows 9x the following setup of CONFIG.SYS and AUTOEXEC.BAT will be suitable.  This setup also ensures access to CD-ROM drive and soundcard in MS-DOS mode.

Before you begin to make alterations of CONFIG.SYS and AUTOEXEC.BAT, it will be suitable to change the setup, so that Windows 9x will not start automatically, but there instead is started directly in DOS mode.

This is done by making the following changes under [Options] in the file C:\MSDOS.SYS:

Tip (by Tom...): Add (or change) this to file C:\MSDOS.SYS in order to skip the logo and speed up you boot. Instead you'll see the dos commands executed during startup:

MSDOS.SYS is a hidden read-only system file, why it is necessary to execute the command:  ATTRIB -H -R -S C:\MSDOS.SYS  before the file can be edited (some editors allows editing without doing this in advance).

After this change the computer will start in MS-DOS 7.x, and the Windows 9x Logo (the one with the running colours beneath the picture) will not be shown during startup, making it possible to see how CONFIG.SYS and AUTOEXEC.BAT are executed.

Windows 9x can subsequently be started manually with the command:  WIN

If for instance a DOS game will not run under a standard installation of Windows 9x, this can often be solved by disabling the automatic start of Windows 9x in this way, and then starting the program before loading Windows 9x.

Once CONFIG.SYS and AUTOEXEC.BAT are optimized, the changes in MSDOS.SYS can be reversed, to reestablish the automatic start of Windows 9x and the Logo, if so wanted.  Alternatively the command:  WIN  could just be inserted as the last line in AUTOEXEC.BAT.

The following example applies to a PC with:

The example are generally applicable, but line 13 and line 24 must be edited, as the drivers for CD-ROM drive and Mouse depends on the manufacturer.

The Lines with * can be omitted.

1. Switches off Num Lock on the keyboard.
2. Extends Control-C / Control Break also to work under I/O operations as for instance reading and writing of the disks.
3. HIGH loads DOS buffers in HMA (requires a XMS manager, line 10).
   UMB allows the use of Upper Memory Blocks for resident drivers and programs (requires an EMS manager, line 11).  This frees up more conventional memory for your applications.
   NOAUTO makes it possible to load drivers and TSR programs in conventional memory, if wanted - otherwise DOS 7.x always tries to load in Upper Memory, even though DEVICEHIGH, FILESHIGH etc. has not been used.  Some drivers can only work if loaded low with a DEVICE command.
4. Sets the number of files that can be opened at one time to 40 (suitable for most instances, but some programs insists on a larger number).
5. Sets the minimal number of file control blocks.  Is only used by very old programs.
6. Sets buffers to 30.  If the number is smaller there is a risk that it is NOT possible to "Restart the computer in MS-DOS mode" from Windows 95 (OSR2).
7. Sets the last logical drive-letter to J:
8. Sets stacks as Microsoft recommends it for Windows 9x.
9. Sets country to 45 (Denmark), with codepage 865 as the system character set i. e. the character set that is used for sorting and conversion to and from capital letters.  If no number is stated for the codepage, then the system codepage is set to 850 by default (for country 45), even though for instance codepage 865 is chosen in line 22.  Therefore the same codepage should always be stated in line 9 and in line 22 to avoid problems with access to files with names, in which characters from the extended ASCII character set are used (character no. 128 to 255) i.e.  ø and Ø.
10. Loads the DOS XMS manager.  Necessary for the next line and for Windows 9x and Smartdrive (line 19).
11. Loads the DOS EMS manager.  RAM indicates that both Expanded Memory (EMS) and Upper Memory (UMB) should be made available.  /MIN=0 states that no minimal amount of EMS memory shall be secured.  I=B000-B7FF indicates that the memory reserved for monochrome screens can be used as Upper Memory.  If EMS memory is not wanted, the parameter RAM can be changed to NOEMS, but from DOS 6.00 an above EMM386.EXE provides both EMS and XMS memory for the programs, so there is no reason not to use the RAM parameter, unless there is a need for more UMB memory and you don't have any programs that demands EMS memory.  Many games requires EMS.
12. Loads the DOS EGA/VGA driver for use of 1 codepage (character set) on the screen.  In DOS 7.x more memory is used for 2 codepages than for 1 codepage.
13. Loads the driver for the CD-ROM drive.  Specific for the installed drive.  Your driver might have another name.  What is written after /D: must also be written after /D: in line 18.  Some other parameters might also be necessary i.e. a statement of the controller's address (/SBP:220 or the like), if the drive is connected via the soundcard or a separate controllercard.  If you haven't got a DOS CD-ROM driver, then you might use the SAMPLE.SYS driver located at the Windows 95 installation diskette.  On the Windows 98 installation diskette is placed a larger number of CD-ROM drivers, covering most CD-ROM drives.
14. Reports an earlier version of DOS (e.g. version 6.22) to older DOS-programs, if they demand to be executed under a definite DOS version.
15. Loads the driver for Windows 9x's 32-bit file access.
16. States the name and location of the command interpreter.  /E: states the size of the DOS environment.  1024 is suitable, as DOS 7.x automatically adds 1040 to the size which cannot be less than 256.  /P indicates that the command interpreter shall stay resident and that AUTOEXEC.BAT shall be executed.  /P may NOT be omitted.
     

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17. Hides the text in batch programs when the batch file is executed.
18. Loads the DOS CD-ROM extension for access to the CD-ROM drive.  Requires that a CD-ROM driver (line 13) with the same text after /D: is loaded.  /M:15 states a suitable amount of buffers, and /E states that these buffer shall be loaded into Expanded Memory (requires that an EMS manager is loaded, line 11).  /S indicates that the CD-ROM drive can be shared over a network, but is also necessary for some programs in order to make it possible to read the volume label on the CD-ROM disks.  /L:D indicates that drive-letter D shall be assigned to the CD-ROM drive.  If /L: is omitted, the first free drive-letter is assigned to the CD-ROM drive.
19. Loads the DOS Smartdrive disk cache for faster reading and writing on the (hard)disks.  When Smartdrive is loaded AFTER MSCDEX (line 18), the cache will also work for the CD-ROM drive.  Requires that a XMS manager is loaded (line 10).  2048 states the amount of memory in Kb that should be used under DOS, and 16 states the amount when running Windows.  The latter is set to the minimum value, because Windows 9x has its own 32-bit disk cache.
20. Increases the typematic rate and delay for the keyboard.
21. Prepares Danish/Norwegian (865) codepage (character set) for the screen.  Requires that DISPLAY.SYS is loaded (line 12).  C:\DOS\EGA.CPI can be replaced with the name of another codepage information file, for instance C:\DOS\865.CPI under IBM's PC DOS.
22. Selects Danish/Norwegian codepage (character set) for the screen.  Requires that line 21 is executed.
23. Loads the keyboard driver, configurated for a Danish keyboard with support for codepage 865.
24. Loads the Mouse driver.  Your driver might have another name.  The drivers from Microsoft and IBM uses a lot of memory - try to get another driver if you have one provided by Microsoft or IBM.
25. Loads DOSKey, which enables fast recalling and editing of the command line at the DOS prompt.  Can be omitted.
26. Set the DOS prompt to show the current directory followed by the character >.
27. PATH indicates in which directories and in which order programs shall be searched for, when no path is stated before the program name.  Many programs inserts their own path in this line during program setup, but in the most instances this is not necessary. Try removing the program path and check if the program can work without it.  A long PATH can slow down the start of the programs on the computer.  The PATH line can not contain more then 127 characters.  Furthermore the length of the PATH is limited by the size of the DOS environment (line 16).
28. Sets the DOS DIR command for pausing, when the screen becomes full, and to display all files including hidden and system files.
29. States in which directory temporary files can be placed by the applications.  This makes it much easier to find files that are not removed due to program errors.  Quite a lot of megabytes can be saved by deleting the files in this directory from time to time.  Do NOT delete these files, while Windows is running - some of them might be in use.
30. States in which directory temporary files can be placed by the applications (older programs).
31. States where the files for the Sound Blaster soundcard are installed.
32. States that the soundcard is installed at Address 220 with IRQ 5, Low DMA on DMA-channel 1, High DMA on DMA-channel 5, MIDI address 330 and that the soundcard is Type 6 (Sound Blaster 16 compatible).
33. Indicates how MIDI-files has to be played.  MAP:G makes sure that both basic MIDI and extended MIDI can be played in DOS.
34. Sets the soundcard to the values in line 32.
35. Sets the volumelevel for the different channels of the soundcard according to the values saved in the file C:\CTSND\CTMIX.CFG by means of the program C:\CTSND\SB16SET.EXE.  Can be omitted.

/L: indicates in which UMB block the driver/program shall be loaded.

/V indicates that the driver/program shall display extended information on the screen when loading.

If the Upper Memory in the address interval C800 to EFFF is unbroken, it should now, depending on the memory requirements for the CD-ROM and Mouse drivers, be possible to load all drivers and resident programs in Upper Memory, giving approximately 625 Kb free memory (can be checked with the command:  MEM /C).

An unbroken Upper Memory area is among other depending on the computers BIOS, the installed videocard and other plug-in cards installed in the computer.

If there is not 625 Kb of free memory, the MEMMAKER program can be tried, but this program cannot always improve the memory utilization, and some times it becomes worse.

Also look at the chapter:  More Upper Memory with EMM386.

More commands for use in CONFIG.SYS and AUTOEXEC.BAT can be seen in the chapter:  MS-DOS 6.22 (Windows 3.11).

Windows 95 OSR2 and HIMEM.SYS

If you are using one of the FIRST German or Danish (and probably some other non-US versions) of the OEM Service Release 2 (OSR2) version of Windows 95, there is an ERROR in the IO.SYS system file, which prevents HIMEM.SYS from loading in the HMA area, leading HIMEM.SYS to use 45 Kb of conventional memory instead of 1 Kb.

You can download the IO2PATCH.EXE program here.  This program fixes the problem.  Just put the IO2PATCH.EXE file in the root of your bootup drive (usually C:\), where the IO.SYS system file is placed, execute the IO2PATCH program, and then the problem should be fixed.

DOSSTART.BAT (Windows 95 & 98)

Whenever it is chosen to "Restart the computer in MS-DOS mode" when closing Windows 9x, the file C:\WINDOWS\DOSSTART.BAT is searched for, and the lines herein are executed, if this file exists.

During installation of Windows 9x some lines are often moved from AUTOEXEC.BAT to DOSSTART.BAT, so it is essential to check that none of the drivers and TSR programs loaded from AUTOEXEC.BAT are loaded by DOSSTART.BAT as well.

The CD-ROM extension MSCDEX is one of the programs that Windows 9x often moves to DOSSTART.BAT.  This is done in order for Windows 9x to use its 32-bit driver for the CD-ROM drive, but if access to the CD-ROM drive is wanted before starting Windows 9x (e.g. if automatic start of Windows 9x is disabled, as earlier described), then MSCDEX HAS to be loaded from AUTOEXEC.BAT and therefore should be deleted from the DOSSTART.BAT file.  Windows 9x's 32-bit CD-ROM driver should be a little faster than a 16-bit DOS driver, but some programs cannot run with the 32-bit driver.

However, if it is chosen to load MSCDEX from DOSSTART.BAT, then SMARTDRV should be moved hereto as well, in order to obtain caching of the CD-ROM drive.  Otherwise SMARTDRV would be loaded before MSCDEX, causing the CD-ROM drive not to be cached.  The DOSSTART.BAT file should then look like this:

and line 18 and line 19 should be deleted from AUTOEXEC.BAT.

WINSTART.BAT (Windows 95 & 98 and Windows 3.11)

Windows looks for the file C:\WINDOWS\WINSTART.BAT before starting.  So, if you for any reason want to run any programs or commands before starting Windows, you can put them into this file.  Unlike DOSSTART.BAT, WINSTART.BAT is also executed by Windows 3.11.

MS-DOS 6.22 (Windows 3.11)

The following example applies to a PC with:

but will also work with MS-DOS 6.00 / 6.20 or PC DOS 6.30 / 7.00.

The example are generally applicable, but line 15 and line 26 must be edited, as the drivers for CD-ROM drive and Mouse depends on the manufacturer.

The Lines with * can be omitted.

1. Switches off Num Lock on the keyboard.
2. Extends Control-C / Control Break also to work under I/O operations as for instance reading and writing of the disks.
3. HIGH loads DOS buffers in HMA (requires a XMS manager, line 10).  UMB allows the use of Upper Memory Blocks for resident drivers and programs (requires an EMS manager, line 11).  This frees up more conventional memory for your applications.
4. Sets the number of files that can be opened at one time to 40 (suitable for most instances, but some programs insists on a larger number).
5. Sets the minimal number of file control blocks.  Is only used by very old programs.
6. Sets buffers to 10, which is appropriate, when Smartdrive (line 20) is used.
7. Sets the last logical drive-letter to J:
8. Sets stacks as Microsoft recommends it for Windows 3.11.
9. Sets country to 45 (Denmark), with codepage 865 as the system character set i. e. the character set that is used for sorting and conversion to and from capital letters.  If no number is stated for the codepage, then the system codepage is set to 850 by default (for country 45), even though for instance codepage 865 is chosen in line 23.  Therefore the same codepage should always be stated in line 9 and in line 23 to avoid problems with access to files with names, in which characters from the extended ASCII character set are used (character no. 128 to 255) i.e.  ø and Ø.
10. Loads the DOS XMS manager.  Necessary for the next line and for Windows 3.11 and Smartdrive (line 20).
11. Loads the DOS EMS manager.  RAM indicates that both Expanded Memory (EMS) and Upper Memory (UMB) should be made available.  /MIN=0 states that no minimal amount of EMS memory shall be secured.  I=B000-B7FF indicates that the memory reserved for monochrome screens can be used as Upper Memory.  With Windows 3.11 the use of I=B000-B7FF requires the following line in C:\WINDOWS\SYSTEM.INI:
     
             [386Enh]
             device=c:\dos\monoumb.386
     
    NOTE!  If you don't have the file MONOUMB.386, then I=B000-B7FF can NOT be used, if Windows is to be run.  In that case all instances of /L:2 must be changed to /L:1.  You can download MONOUMB.386 here.
    If EMS memory is not wanted, the parameter RAM can be changed to NOEMS, but from DOS 6.00 an above EMM386.EXE provides both EMS and XMS memory for the programs, so there is no reason not to use the RAM parameter, unless there is a need for more UMB memory and you don't have any programs that demands EMS memory.  Many games requires EMS.
12. Loads the DOS ANSI driver, which among other makes manipulating of the colours in the DOS prompt (line 30) possible.  Can be substituted with an ANSI driver specific to the installed videocard.  DOS's ANSI.SYS uses a lot of memory.  Can be omitted.  Some older programs requires an ANSI driver.
13. Loads the DOS EGA/VGA driver for use of up to 2 codepages (character sets) on the screen.  In DOS 6.22 no more memory is used for 2 codepages than for 1 codepage.
14. Loads the driver for Windows 3.11's 32-bit file access.
15. Loads the driver for the CD-ROM drive.  Specific for the installed drive.  Your driver might have another name.  What is written after /D: must also be written after /D: in line 18.  Some other parameters might also be necessary i.e. a statement of the controller's address (/SBP:220 or the like), if the drive is connected via the soundcard or a separate controllercard.
16. States the name and location of the command interpreter.  /E: states the size of the DOS environment.  512 or 1024 is suitable.  If the number is smaller then some programs and batch-files might not run.  /P indicates that the command interpreter shall stay resident and that AUTOEXEC.BAT shall be executed.  /P may NOT be omitted.
     

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17. Hides the text in batch programs when the batch file is executed.
18. Loads the DOS CD-ROM extension for access to the CD-ROM drive.  Requires that a CD-ROM driver (line 15) with the same text after /D: is loaded.  /M:15 states a suitable amount of buffers, and /E states that these buffer shall be loaded into Expanded Memory (requires that an EMS manager is loaded, line 11).  /S indicates that the CD-ROM drive can be shared over a network, but is also necessary for some programs in order to make it possible to read the volume label on the CD-ROM disks.  /L:D indicates that drive-letter D shall be assigned to the CD-ROM drive.  If /L: is omitted, the first free drive-letter is assigned to the CD-ROM drive.
19. Inserts a blank line (remember the period after ECHO).
20. Loads the DOS Smartdrive disk cache for faster reading and writing on the (hard)disks.  When Smartdrive is loaded AFTER MSCDEX (line 18), the cache will also work for the CD-ROM drive.  Requires that a XMS manager is loaded (line 10).  2048 states the amount of memory in Kb that should be used under DOS, and 128 states the amount when running Windows.  128 Kb is recommended when 32-bit file access is used, otherwise 2048 will be proper (having 8 Mb RAM or more).
21. Increases the typematic rate and delay for the keyboard.
22. Prepares Danish/Norwegian (865) and international (850) codepage (character set) for the screen.  Requires that DISPLAY.SYS is loaded (line 13).  C:\DOS\EGA.CPI can be replaced with the name of another codepage information file, for instance C:\DOS\865.CPI under IBM's PC DOS.
23. Selects Danish/Norwegian codepage (character set) for the screen.  Requires that line 22 is executed.
24. Loads the keyboard driver, configurated for a Danish keyboard with support for codepage 865.
25. Inserts a blank line.
26. Loads the Mouse driver.  Your driver might have another name.  The drivers from Microsoft and IBM uses a lot of memory - try to get another driver if you have one provided by Microsoft or IBM.
27. Loads DOSKey, which enables fast recalling and editing of the command line at the DOS prompt.  Can be omitted.
28. Inserts a blank line.
29. Loads national language support, which makes it possible to change the codepage with the command:  CHCP.  If C:\DOS\COUNTRY.SYS is not stated, the country information file stated at COUNTRY=   in CONFIG.SYS (line 9) is used.  Can be omitted.
30. Makes a little fun with the DOS prompt.  Requires that an ANSI driver (line 12) is loaded.  The cross is made by holding down the ALT key and typing 196 and 197 on the numeric keypad at the right side of the keyboard (not all text editors supports this).  Alternatively the prompt can just be set to: $p$g
31. PATH indicates in which directories and in which order programs shall be searched for, when no path is stated before the program name.  Many programs inserts their own path in this line during program setup, but in the most instances this is not necessary. Try removing the program path and check if the program can work without it.  A long PATH can slow down the start of the programs on the computer.  The PATH line can not contain more then 127 characters.  Furthermore the length of the PATH is limited by the size of the DOS environment (line 16).
32. Sets the DOS DIR command for pausing, when the screen becomes full, and to display all files including hidden and system files.
33. States in which directory temporary files can be placed by the applications.  This makes it much easier to find files that are not removed due to program errors.  Quite a lot of megabytes can be saved by deleting the files in this directory from time to time.  Do NOT delete these files, while Windows is running - some of them might be in use.
34. States in which directory temporary files can be placed by the applications (older programs).
35. Sets the timezone to GMT-1 (Central European Time), with correction for Daylight Saving Time.  Used by E-mail programs and News readers.
36. States where the files for the Sound Blaster soundcard are installed.
37. States that the soundcard is installed at Address 220 with IRQ 5, Low DMA on DMA-channel 1, High DMA on DMA-channel 5, MIDI address 330 and that the soundcard is Type 6 (Sound Blaster 16 compatible).
38. Indicates how MIDI-files has to be played.  MAP:G makes sure that both basic MIDI and extended MIDI can be played in DOS.
39. Sets the soundcard to the values in line 37.
40. Sets the volumelevel for the different channels of the soundcard according to the values saved in the file C:\SB16\CTMIX.CFG by means of the program C:\SB16\SB16SET.EXE.  Can be omitted.

/L: indicates in which UMB block the driver/program shall be loaded.

/V indicates that the driver/program shall display extended information on the screen when loading.

If the Upper Memory in the address interval C800 to EFFF is unbroken, it should now, depending on the memory requirements for the CD-ROM and Mouse drivers, be possible to load all drivers and resident programs in Upper Memory, giving approximately 611 Kb free memory (can be checked with the command:  MEM /C).

An unbroken Upper Memory area is among other depending on the computers BIOS, the installed videocard and other plug-in cards installed in the computer.

If there is not 611 Kb of free memory, the MEMMAKER program can be tried, but this program cannot always improve the memory utilization, and some times it becomes worse.  Especially KEYB.COM can cause problems.

Also look at the chapter:  More Upper Memory with EMM386.

PC DOS 7.00 (IBM)

The setup above will work with IBM's DOS as well.  The resident programs in version 7.00 typically uses a little lesser memory than the ones of MS-DOS 6.22, and IBM's DOS versions are translated to Danish.  The translation is awful in places and even more difficult to understand than the original English, but that goes for the Danish Microsoft MS-DOS version 7.x (Windows 9x) too.

Under PC DOS, the program RAMBOOST can be used for memory optimization, but this program isn't flawless either, and it is furthermore a resident program consuming memory itself.

Note that PC DOS's Smartdrive 5.00 not as standard uses write cache as MS-DOS's Smartdrive does.  To obtain write caching, the drives to be cached has to be stated succeeded by a + (SMARTDRV C+ D+ E+ etc.).

PC DOS's Smartdrive 5.00 indicates that CD-ROM drives are cached.  Tests with CD-Bench 1.07 states that this is not the fact when using PC DOS's MSCDEX.EXE 2.25, whereas CD-ROM drives are cached under PC DOS if MS-DOS's MSCDEX.EXE is used.

Windows 3.11

If a DOS version above DOS 5.00 is used, then the versions of HIMEM.SYS, EMM386.EXE and SMARTDRV.EXE installed by Windows in C:\ should NOT be used.  Use the corresponding files in the DOS directory instead.

It can be suitable or necessary to add the following lines to the SYSTEM.INI file in the Windows directory:

1. If the EMM386 Memory Manager is used with the parameter I=B000-BFFF, then the MONOUMB.386 device driver HAS to be used.  MONOUMB.386 can be downloaded here.
2. If Quarterdeck's QEMM386 Memory Manager is used, then SystemROMBreakPoint HAS to be set to FALSE.
3. Increases the maximum breakpoints that can be used by the Virtual Memory Manager (VMM) from 200 to 768.  This can improve Windows' performance.

More Upper Memory with EMM386

If there is not enough Upper Memory for all drivers and TSR programs, then line 11 can be extended to:

     DEVICE=C:\DOS\EMM386.EXE RAM I=B000-B7FF HIGHSCAN FRAME=C800 /MIN=0 /V

HIGHSCAN tells the Memory Manger to search the system area (F000-FFFF) for unused memory, and FRAME=C800 places the page frame in the start of Upper Upper Memory Block number 2 (UMB 2), and thereby increases the probability for an unbroken UMB 2 from D000 and up.

Depending on the BIOS this might cause the computer to hang during bootup!  First try removing the FRAME=C800 statement.  This might lead to a third UMB block placed after the page frame.  If this is the case, some of the drivers and/or TSR programs must be loaded into UMB 3 using a DEVICEHIGH /L:3 =  or a  LH /L:3  statement.  If removing the FRAME=C800 statement still causes the computer to hang, then the HIGHSCAN statement must be removed as well.  Then it is not likely that any more Upper Memory can be gained using EMM386

It is possible that the computer works alright in DOS, but that Windows 9x cannot start when HIGHSCAN is used.

If HIGHSCAN cannot be used, then perhaps an alternative Memory Manager can be used instead to obtain more Upper Memory.

Alternative Memory Managers (QEMM386)

If there is a demand for more Upper Memory, an investment can be made in an alternative Memory Manager, as for instance Quarterdecks QEMM386.  This manager can typically give 32 Kb or more extra Upper Memory, an DOS will typically run 20% faster than with the Memory Manager provided by MS-DOS or PC DOS!!!

I use QEMM386 v. 8.03 with MS-DOS 6.22 myself, and my CONFIG.SYS, AUTOEXEC.BAT and DOS-UP.DAT files looks like the following.  Here might be something to obtain for other QEMM386 users.  The setup also shows how to make a startup menu with two configurations - one for running with QEMM386, which starts by default after 2 seconds, and one for running with EMM386:

This results in 632 Kb free memory with QEMM386 and 607 Kb free memory with EMM386.

Furthermore there is now room in Upper Memory for the two drivers C:\SB16\DRV\CTSB16.SYS and C:\SB16\DRV\CTMMSYS.SYS, which makes it possible to playback WAV, MID, CMF and VOC soundfiles under DOS, using the program C:\SB16\PLAY.EXE.  These drivers are provided with the Sound Blaster 16 soundcard.

If there is not enough Upper Memory for all drivers and resident programs, the line:  DEVICE=C:\QEMM\QEMM386.SYS R:1 RAM  can be expanded with the parameter:  ST:F (safest) or ST:M  (this should be tested with the Quarterdeck OPTIMIZE program).

If DoubleSpace, DriveSpace or Stacker disk compression is used, then the parameter:  DBF=2  HAS to be added to the line mentioned above.

If there is not 632 Kb of free memory with QEMM386, the OPTIMIZE program can be tried, but this program cannot always improve the memory utilization, and some times it becomes worse.  Especially KEYB.COM can cause problems.

If the computer hangs under startup after an apparently successful OPTIMIZE, it might be because OPTIMIZE has added squeezing to the LOADHI procedure for some of the programs.  Boot again and press F5.  Then run the following command:  C:\QEMM\OPTIMIZE /NOSQT /NOSQF.  This starts OPTIMIZE with Temporary- and Frame squeezing turned off.

If version 7.x of Quarterdeck is used, it can not be recommended to use DEVICE=C:\QEMM\DOSDATA.SYS, because there will be SO MUCH free memory, that some programs (Windows, among others) refuses to start.  In most instances you can circumvent this by starting the programs with the MS-DOS LOADFIX program.  Version 8.x of Quartedeck seems to take hand of the problem by itself.

Stacker disk compression

If Stacker version 3.x or 4.x is used, the following can be entered into CONFIG.SYS, AUTOEXEC.BAT and STACKER.INI.  Stacker is presumed installed in C:\STACKER, and there is two physical harddisks (C: and D:).

The Quarterdeck parameter:  DBF=2 HAS to be used with Stacker.

It is best to use Stacker with minimum compression, and then at regular intervals run a full optimization with maximal compression by means of the command:  C:\STACKER\SDEFRAG /R /SU.  This may last up to 1 hour for a Stacker file of 512 Mb.

With Stacker 4.x the DEVICE=C:\STACKER\DPMS.EXE statement can be used in CONFIG.SYS to create DPMS memory, in which Stacker can be loaded, but this might cause problems with other programs as for instance PKZIP or QEMM386 with Stealth (ST:F / ST:M).  DPMS can also NOT be used if 32-bit file access to the compressed drives is wanted under Windows.  So if EMS memory is available, it is better to use this, than to use DPMS memory.

Harddisk partitioning

If you do not want to compress your harddisk, you can often obtain more space by partitioning the disk by means of the program FDISK.EXE.  This reduces the amount of space wasted by each of the files on the disk.

The amount of wasted space is among other things dependent on the size of the disk, as the waste is bigger on large disks, because DOS has to use larger clusters (allocation units) on large disks than on small disks.

One file always takes up a whole number of clusters, and therefore a file of just 1 byte will use 16.384 bytes = 1 cluster on a harddisk of 1023 Mb and 32.768 bytes on a harddisk bigger than 1023 Mb!  The average waste of space on a harddisk bigger than 1023 Mb will be 40% !!, while the waste on a harddisk between 512 and 1023 Mb will be 20%, and on a harddisk of 511 Mb it will only be about 10%.  Smaller files typically results in more waste of space, as do large numbers of directories and subdirectories, because these also occupy 1 cluster each.

If you have 2 harddisks, both partitioned to 2 drives, then the first harddisk (harddisk 0) will contain the logical drives C: and E:, while the other harddisk (harddisk 1) will contain the logical drives D: and F: after the partitioning.  During the partitioning it is important to remember to set the primary partition on disk 0 to be the active partition, otherwise drive C: will not be bootable

Commercial- and shareware-programs that can make disk partitioning without loss of data are available, for example PowerQuest's PartitionMagic.

Windows 95 OSR2 and FAT32

The OEM Service Release 2 (OSR2) version of Windows 95 uses FAT32 instead of the previously used FAT16 file system.  FAT32 uses smaller clusters (typically 4.096 bytes) and supports harddisk partitions of a size up to 2 Terrabytes (2048 Gb), whereas FAT16 only could handle harddisk partitions with sizes up to 2 Gb.

Because of the smaller clustersize used by FAT32, there is no longer the same need for harddisk partitioning in order of reducing the amount of wasted disk space.  However, if you have a large harddisk (4 Gb or more), harddisk partitioning can still give you a better overview of your folders and files.

OEM stands for: "Original Equipment Manufacturer", which means that the OSR2 version of Windows 95 can only be purchased in conjunction with buying a new computer (or sometimes when buying a new harddisk).

With Windows 98 it is possible to convert a FAT16 partition to FAT32.