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░░░░░░░▄ ░░░░▄ ░░░░░░░▄ ░░░░▄ ░░░▄ ░░█▀▀░░░▄ ░░█▀ ░░█▀▀▀▀░▒▄ ░░█▀ ░░█▀▀ ░░░▄ ░░░▄ ░░█ ░▒█ ░░█ ░▒█ ▀▀ ░░█ ░▒█▀ ░░▄ ░▒█▀▀ ░░█ ▒▒█ ░▒█ ░▒█ ░░█▒▒█▀ ░▒▒▒█▀ ░▒█ ▒▒█ ▒▒█ ▒▒▒▒▒▒▒▄ ░▒▒▒█▀ ▒▒█▀ ▒▒█ ▒▓█ ▒▒█ ▀▀▀▀▀▒▓▄ ▒▒█▒▓▄ ▒▒▓▓▄ ▒▒█ ▓▓█ ▒▓█ ▓▓█ ▒▒█ ▓▓▄ ▓▓█ ▓▓▄ ▒▓█ ▓▓▓█ ▓▓█ ▒▒▄ ▓▓█ ▒▓█ ▓▓▄ ▓▓▓█▀ ▓▓▓▄ ▓▓▓▓▓▓▓▓█▀ ▓▓▓▓▄ ▓▓▓▓▓▓▓█▀ ▓▓▓▓▄ ▓▓▓▄ ▀▀▀ ▀▀▀ ▀▀▀▀▀▀▀▀ ▀▀▀▀ ▀▀▀▀▀▀▀ ▀▀▀▀ ▀▀▀▀ Version 3.31 Copyright (c) 1989, 1990, 1991, 1992 FM de Monasterio Licensed Material - All Rights Reserved SUMMARY xDISK generates RAM-disks in expanded memory and permits to vary the amount of memory allocated to the disk(s) without rebooting the computer when used with expanded memory conforming to the LIM 3.0+ specification (EMS). If DOS version 3.xx or higher is used, the RAM-disk can be collapsed completely to free all of its EMS to another process (with DOS 2.10, the disk can be made as small as 16 kbyte [an EMS page]). Also, the RAM-disk can be expanded to use all of the available EMS or any intermediate size multiple of 16 kbyte, sector size and number of root directory entries can be changed, and it can be made to show visual clues of its activity. If disk contents need not be preserved, resizing is only limited by the amount of EMS; a more restricted resizing is availble if the RAM-disk contents need to be preserved. Security features include making the disk a Read-Only or Read-Write device, locking/unlocking DOS access to the disk, and the enforcing of user-defined password checks before the implementation of any command to the disk. Loading features include installation of the xDISK driver program XDISK.SYS in the upper memory area, with or without MS-DOS 5.0, if an extended memory manager is present, and the capability of loading this driver directly from the DOS command line via the interface program XDISK.EXE (under DOS version 2.x through 4.x only). Requires MS-DOS/PC-DOS version 2.1 or later, and expanded memory conforming to the LIM EMS 3.0 or later. The upper-memory selfloading requires DOS 3.0 or later. It is available in 086+, 286+, 386+, and 486+ microprocessor-type optimized versions. -------------- REGISTRATION This software is user-supported; the present release, although lacking the options marked by asterisks, is a fully usable program. You may test this release for (in)compatibilities with your system, but after the testing is completed you are requested to order a registered copy of the full release of the software from the address at the end of this documentation. If you would rather use this unregistered copy, consider making a donation to the Children's Hospital of Washington DC, for indigent children in need of medical care. Every year in the USA, infant mortality claims the lives of tens of thousands of children before their first year of life, and most of them come from families below poverty level... Please send to the same address a check payable to the "PATIENT CARE FUND, CHILDREN'S HOSPITAL" on the obverse, and marked "For Deposit Only" on the reverse. Donations will be sent to Children's Hospital. Please identify the program for which you are making the donation. -------------------------------------------------------------------------- XDISK.REG contains a form needed to register or upgrade the Software -------------------------------------------------------------------------- See the final part of this documentation for information on the Licensing, Distribution, Warranty, and Limitation of Remedies of this software. -------------- 1. GENERAL INFORMATION xDISK is a virtual-device driver system to generate (and modify) RAM-disks in expanded memory conforming to Lotus/Intel/Microsoft specification version 3.0 or higher. Disk parameters can be modified without having to reboot the CPU. The disk contents are lost if the resizing requires reformatting of the disk. Under EMS 4 and MS-DOS 3 (or compatible operating system) or higher versions, however, a limited, data-safe resizing can be obtained with some switches. This system consists of two programs: (1) XDISK.SYS, a block device driver to be installed via CONFIG.SYS, after an EMS manager has been installed, and (2) XDISK.EXE, a utility to communicate with the device driver via DOS and, thus, to permit changing of one or more parameters of a specified xDISK RAM-disk. The XDISK.SYS and XDISK.EXE files of a given version are matched and will not work with those of other xDISK versions. Minimum requirements are: 16 kbytes or more of expanded memory, an EMM supporting version 3 or higher of the LIM- EMS, and MS-DOS (or compatible operating system) version 2.10 or higher. Some program options require higher versions of DOS or EMS, or both (see below). xDISK RAM-disks are compatible with the CHKDSK utility of DOS as well as with other programs that sometimes encounter difficulties with other resizable RAM disks. Starting from version 2.50, the boot sector of the xDISK disk complies with the MS-DOS 4+ format. CPU VERSIONS The program is written in assembly language; each version consists of four processor-type releases (086, 268, 386 and 486) in which the code has been optimized for the CPU types of the Intel iAPX processor family (x86). This is needed because such processors differ markedly in instruction execution time. Incorporation of a memory cache in some x86 processors also affects this time by influencing the speed of both instruction fetching and memory access. In addition to standard (086) assembly language instructions, the 286, 386 and 486 releases of the program also use 286-, 386- or 486-specific opcode instructions in 'real' mode (which is the native mode for 086 processors). The type and degree of code optimization vary with the CPU type, and yield usually small variations of the size of the resident code. -------------- 2. USAGE INSTALLING THE xDISK DRIVER XDISK.SYS may be installed via the CONFIG.SYS file on the boot disk after the LIM-3+ EMS manager has been installed. The filename of the EMS driver varies varies with the manufacturer, but its code must include the string 'EMMXXXX0' whose presence can be verified with any file-browsing utility. The following command must be included in the CONFIG.SYS file: DEVICE=[path]XDISK.SYS [/B/C/D/E/H/K/S] Alternatively, starting from version 3.10, the driver may also be loaded from the command line at the DOS prompt (i.e., after the operating system has been booted and configured via CONFIG.SYS) by means of the utility XDISK.EXE, when executed under DOS versions 2 through 4. The DOS command-line loading is not implemented yet under MS-DOS version 5. The following command must be issued for the command-line loading: XDISK /L [path]XDISK.SYS [/B/C/D/E/H/K/S] If given, <path> represents the complete path specification (including drive) for the file XDISK.SYS. See below for a description of the switches. MODIFYING THE xDISK DRIVER After the xDISK driver has been installed, XDISK.EXE can be used to interface with the driver. This utility allows for the modification of disk parameters from the DOS command line: XDISK [?] [/L] [d: [/A/B/C/D/E/F/G/N/P/Q/R/S/U/V/X/?]] ? If xDISK is executed with <?> as the only argument (notice the absence of a preceding backslash), the program searches all block device drivers for the xDISK driver signature, and displays a list of the installed drivers. d This is the drive designator letter, followed by <:>, that identifies the xDISK drive. The use of letters for non-xDISK drives and for non-existing drives generates separate error messages (IOctl error 1 and F). Defaults: Null drive, no colon or x=<ASCII 21-40> = Current drive letter. NOTE: Switch /L does not require a drive designator specification for the DOS command-line loading of the xDISK driver. -------------- 2.1 SWITCHES The switches are not case sensitive, but must be preceded by a backslash [/]. If the RAM-disk is being resized (i.e., /Bn/Sn/Dn/C/E), non-resizing switches must be specified AFTER the resizing switch(es), except in the case of switch /L when the resizing switches apply to the driver to be loaded. -------------------------------------------------------------------------- (*) Asterisks mark options available in the registered program copy only -------------------------------------------------------------------------- NOTE: When xDISK is invoked without any switch (or when the switches are not preceded by slashes [and thus are ignored]), the status of the xDISK drive is displayed on the DOS command line. Except during the XDISK.SYS installation, such a null-switch call does not change any RAM-disk parameters. During xDISK installation, however, default values for switches /B, /D, and /S are used if the corresponding switch is not specified. SWITCH ? This switch displays the Status/Usage/Help panels, which are described in more detail in the section below. If a VGA or EGA is the active adapter, the program saves the contents of the palette registers prior to changing the video attributes for its various displays. When preceded by a valid xDISK designator, ? or /? displays the status of the specified RAM-disk. In the absence of a drive designator, ? displays the Status/Usage panel listing any installed RAM-drive, while /? attempts to display the status of the default drive. See section STATUS/USAGE/HELP PANELS below. SWITCH A[±] Provides control of audio feedback during DOS access to the specified RAM disk. Use /A+ to enable a brief click each time the driver receives a DOS request, and /A- to disable the feedback. The audio feedback ON status is indicated by the icon [] in the xDISK reconfiguration status messages. Default: /A = /A+. SWITCH B[[-]n] Disk size in kilobytes, where <n> is between 16 and 8196 (EMS 3) or 32768 (EMS 4) in 16-kbyte steps; if <n> is not a 16-kbyte multiple, the size is increased to the nearest larger multiple available. The largest disk size that is supported is either 8 megabytes (EM maximum of EMS 3) or 32 mega- bytes (EM maximum of EMS 4). Unless switch /Q or /N is enabled, resizing changes necessitate confirmation by the user. Starting with version 3.31, there are two usages for this switch: (1) If <n> is not a signed number, i.e. not preceded by a - or + sign, the disk size is reset to <n> kbytes or nearest HIGHER 16-kbyte multiple (n x 16 x 1024 bytes), and the disk is re- formatted and its contents destroyed. (2) If <-n> is a negative number, the current or default size is decreased by <n x 16> kbytes. The contents are preserved if the resulting drive internal parameters can still handle the data without error (see section DISK INTERNALS below). Else, the disk is reformatted and the data destroyed, as otherwise incorrect disk input/output would follow. If switch /N or /Q has not been specified (see below), the user is prompted for a [Y]es or [N]o decision before resizing the disk. This second usage is only available when using EMS 4 and MS- DOS (or compatible operating system) 3.0 or higher versions. Defaults: In the CONFIG.SYS file, null switch or null <n> = /B64. In the command line of DOS, /B = /B64; null switch is ignored. NOTE ------------------------------------------------------------------------- There is no symmetrical operation to increase the size via switch '/B+n', whose use defaults to /B64. Use /Bn to increase size when drive contents need not be preserved; a data-safe, limited expansion may be obtained via switch /X+ (see below). ------------------------------------------------------------------------- SWITCH C Collapses the RAM-disk to a size of 0 kb (DOS ≥3.0) or 16 kb (DOS <3.0). Unless switch /Q or /N is enabled, collapse necessitates confirmation by the user; a 0-kb collapse does not change the existing /D and /S values, but a 16-kb collapse also sets /D=4 and /S=128. If a 0-kb collapse has occurred for, say, the RAM-disk M, a DOS-mediated command to the drive will trigger the folowing error message from MS-DOS 5 (e.g., 'CHKDSK M:' or 'DIR M:') Invalid disk change reading drive M Please insert volume <xDISK M:>, serial 0000-0000 Abort, Retry, Fail? Respond to the "Abort, Retry, Fail?" question of the DOS' critical error handler by pressing <A> to return to the DOS prompt. Such a message is a remainder that the disk does exist, but has collapsed. A collapsed disk can only be restored with switch /B[n] or /E since formatting is needed; data-preserving switches /X± and /B-n are not accepted. No defaults. SWITCH D[n] Number of allowed entries (files) in the root directory, where <n> is in the range between 4 and 512. If the minimum value of 4 entries has been selected, the number of entries is increased to 8 or 16 when a sector of size 256 or of 512 bytes is also selected. Unless switches /Q or /N are enabled, this resizing change necessitates confirmation by the user. Defaults: In the CONFIG.SYS file, null switch or null <n> = /D64. In the command line of DOS, /D = /D64; null switch is ignored. WARNING ------------------------------------------------------------------------ If a sufficient number of entries is NOT available, commands to write to the disk will trigger a critical error message of 'File Creation Error.' To decrease this possibility, expanding the disk to the maximum EMS size via switch /E changes the number of root directory entries to 512. If a smaller number of entries is needed, follow switch /E with /Dn. ------------------------------------------------------------------------ SWITCH E Expands the disk to the maximum available EMS size. If switch /Dn is not also specified, it sets the directory entries to /D512. Unless switch /Q or /N is enabled, this expansion necessitates confirmation by the user. No defaults. SWITCH F Provides control of the audio and visual feedback during the checking of the password (see switch /P below) prior to the implementation of a disk change. Use /FA to produce a 55-ms beep each time an incorrect character is entered, /FV to display a '■' when a correct character is entered, or /F- to disable either feedback. Default: /F = /F+. SWITCH G[±] Provides gate control of DOS access to the specified xDISK disk. Use /G- to disable DOS access to the disk, and /G+ to (re)enable such an access. The RAM disk data are preserved if the access gate is disabled, and they become immediately accessible after the gate is reenabled. Defaults: /G = /G+. SWITCH H[n[!]] Instructs the program to load its resident in high memory between 640 kb and 1024 kb, i.e. below the 1-Mb limit of real-mode memory but above the 640-kb DOS hardware barrier. High memory self-loading requires that an extended memory manager (XMM) supporting the services of the XMS 2.00 is installed and that a free upper memory block (UMB) of a little less than 2 kb is available. The XMM must support functions 10h (Allocate UMB) and 11h (Free UMB). UMB allocation is implemented via calls to DOS, if this allocation is controlled by MS-DOS 5.0 (i.e., command DOS=UMB in CONFIG. SYS and the drivers HIMEM.SYS and 386EMM.EXE loaded), of by direct calls to the XMM, when DOS 5.0 does not control UMB allocation. Switch /H[n]! must be used in the former case, and switch /H[n] in the latter case. If switch /H[n]! is specified but the memory chain control of MS-DOS 5.0 has not been extended to the UMA (e.g. DOS=UMB command not implemented), self-loading in upper memory will fail. The user has then the option of loading the driver in conventional memory or abort its installation. A low high-memory limit for the UMB can optionally be specified via <n>, a hexadecimal number between A000 (640 kb) and FFFF (1,024 kb), so as to select or avoid specific regions of upper memory. The self-loading into upper memory consumes 64 bytes of the conventional memory for each installed xDISK driver. A few additional bytes are used by the XMM or MS-DOS 5 when allocating the UMB. Unlike the upper-memory loading mediated by some memory managers, the self-loading only requires a free UMB of the size of the resident driver code (and not of the whole code of XDISK.SYS). Defaults: Lower-memory installation, if a XMS/DOS error is found during the UMB loading; high-memory installation below requested lower limit if UMBs are not available above this limit. SWITCH K Do not display the installation banner when loading the driver. Switch K is ignored after the driver has been loaded. No defaults. SWITCH L Load XDISK.SYS from the DOS command line (i.e., after the system has been booted, and the drivers installed via the CONFIG.SYS file). The full-path specification for XDISK.SYS must be given after switch L along with other switches used to configure the driver, as listed above in Usage item 2.0, including loading in upper memory. The command-line loading of the driver works successfully with MS-DOS or IBM PC-DOS version 2 through 4, but not yet with MS-DOS 5.0. Any previously installed xDISK drive cannot be collapsed for the command- line loading to work, since such loading process rebuilds the DOS kernel. Command-line loading of the driver adds 256 bytes (the XDISK.EXE program segment prefix) to the resident size. xDISK drives loaded from the command-line either in lower (LMB) or upper memory (UMB) can be unloaded from memory via switch /U (see below). No defaults. WARNING ------------------------------------------------------------------------- DOS will crash if the memory allocated to the driver is released by means of a TSR-removal utility. A command-line loaded driver can be identified in memory maps by the string 'xDISK_<d:>,' where <d> identifies the drive letter for the disk. See section IDENTIFICATION IN MEMORY MAP UTILITIES. ------------------------------------------------------------------------- SWITCH N Nulls the displaying of disk status, user confirmation request, and error messages; errors can still be detected within a batch file with the ERROR LEVEL command. Because the disk status display is generated by the driver via BIOS calls, the messages cannot be redirected by DOS; use of switch N produces the same result as a redirection to the NUL device. The RAM-disk configuration parameters are preserved. No defaults. SWITCH P[x][±] Demand password before implementing changes; password consists of 1 to 15 lower-case, pure alphanumeric characters followed by <Enter>. Use /Px to (re)define a password, where <x> is 1 to 15 alphanumeric lower-case [0-9, a-z] characters followed by a space; use /P- to disable and /P+ to enable the password requirement. Pressing <Esc> or <Break> during password testing returns the user to the DOS command line. The typing of an incorrect character during the testing vitiates prior accepted (correct) characters, and the entire password has to be retyped. Note that warmbooting via <Ctrl-ALt-Del> is not suppressed during password testing (rebooting destroys the RAM-disk data). The password is useful in situations when more than one user has acces to the RAM-disk (e.g., a server) and, after copying the common-access files, the disk is made Read-Only to protect its contents. Default: /P = /P+. SWITCH Q Quiet resizing. Disables the default prompt for user's confirmation prior to disk resize/format operations that destroy all data on the RAM-disk. No defaults. SWITCH R[±] Make the disk a Read-Only [+] or Read-Write [-] device; the current write status is indicated by [RO] or [RW] icons in the configuration message. A Read-Only status does not allow for file changes or resizing of the disk. RAM-disk configuration parameters are preserved. Defaults: /R = /R+. SWITCH S[n] Sector size in bytes, where <n> is 128, 256, or 512. Select a small value if storing small files; large values will reduce reading and writing time if storing larger files. Unless switch /Q or /N is enabled, the resizing change necessitates confirmation by the user. Defaults: In the CONFIG.SYS file, null switch or null <n> = /S256. In the command line of DOS, /S = /S256; null switch is ignored. SWITCH V[±] Turn ON [+] or OFF [-] the display of a "" on the top-left corner of the screen whenever xDISK is active due to a DOS request. The disk parameters are preserved. If the display is on, the icon "" is displayed along with the drive status in answer to the switch /? or <d:>? (see below). Defaults: /V = /V+. SWITCH U Uninstall from memory the specified xDISK drive (only command-line loaded drives can be uninstalled). The operating system will crash if this drive is not the LAST drive in the DOS chain or if the resident code is removed with a TSR-removal utility. No defaults. SWITCH X[±] Permits a limited shrinkage [-] or expansion [+] of the free space of the disk while preserving the integrity of its contents. The resizing is NOT implemented if the resulting internal drive parameters would be unable to handle the disk data without error (see section DISK INTERNALS below). Switch /X- shrinks the disk free space to zero or to less than 16 kbytes. This is an automatic implementation of switch /B-n to minimize EMS usage, where <n> is the disk free space in kbytes to the nearest higher 16-kbyte multiple. If the disk is empty or its free space is less than 16 kbytes, the shrinkage is not implemented. Free-space disk shrinkage is available only if EMS 4.0 and MS-DOS (or compatible operating system) 3.1 or higher versions are used. The amount of shrinkage is computed from the value, maintained by MS-DOS, of the first cluster from which to start the search for free space during disk write operations (such a value is displayed on the Status panel, see STATUS/USAGE/HELP PANELS below). DOS normally uses all of the previously unused free space before reusing freed space. Contents must be compacted (i.e. there should be no free gaps between used clusters) for proper disk shrinkage. Switch /X- compares the calculated kbytes needed to resize the disk with the amount occupied by the data; if the former are smaller than the latter, free gaps are assumed (i.e. the free-space cluster value does not point to the last cluster in use) and shrinkage is not implemented. Switch /X+ expands total disk size to the nearest (higher) multiple of 64 kb provided that the original disk size at the time of formatting was not a multiple of 64 kb. The switch requires EMS 4 and MS-DOS (or compatible operating system) 3.0 or higher. Disks shrunk via /X- can be restored to the original size or a larger one via switch /X+. Defaults: /X = /X+. WARNING ------------------------------------------------------------------------- Switch /X- uses an undocumented DOS function supported in versions 3.1 to 5.0 (revision A and B) of MS-DOS; the function is also supported in other compatible operating systems, such as IBM PC-DOS and some versions of DR- DOS. However, there is no assurance that such a function is available in systems other than MS-DOS, or that it will remain available in future MS- DOS versions or revisions. ------------------------------------------------------------------------- 2.2 COMMENTS Comments may be added in the command after the desired switches. The comments (which may be useful in batch files) must be preceded by a semicolon (;), and are ignored by xDISK. Do not use DOS redirection and pipe characters in these comments, as DOS will attempt to implement the implied redirection/pipe request. -------------- 3. STATUS/USAGE/HELP PANELS Executing the program with switch /? selected allows access to the Status/ Usage and Help panels. (If a Mouse pointing device driver, compatible with the Microsoft Mouse driver version 6.0 or higher is loaded and active, all of the services provided by these panels can also be activated by pointing the mouse to specific regions of the screen and clicking either button.) The STATUS/USAGE panel, which is shown first, describes status information for the resident driver and its drive if an xDISK RAM-drive designator was specified, or a list of the installed xDISK RAM-drives if any. If a valid drive designator was specified, the STATUS subpanel also displays the used and free kbytes, and the value of the first free-space cluster. For disks that are not write protected, the cluster value can be as small as 2 or as large as the disk size; for a write-protected disk, this value is always 0 (see Switch /X above). The USAGE subpanel shows a menu for the command switches: To cycle between the main and the auxiliary menu, press key <F2> or <M>, or click the mouse upon the screen button labelled <Menu>. If the resident is installed, the status of some 'on/off' command switches is displayed by '+' or '-' before a given menu entry. The DIRECTORY subpanel shows the root directory listings for the specified (or default) drive, equivalent to the DOS command 'DIR \'. Press key <F3> or <D>, or click the mouse upon the screen button labelled <Dir\> to reach this display. Press <PgUp> <PgDn> or <> <> keys, or click the Mouse upon the respective screen buttons, to scroll the directory listings; press the <Esc> key, or click the mouse upon the <Esc> button, to return to the main panel. The HELP panel provides a summary description of the program and commands, and is displayed if key <F1> or <H> is pressed from the Status/Usage panel (or if the mouse is clicked upon the screen button labelled <Help>). Press the keypad cursor keys (Home/End, PgUp/PgDn, arrows) to scroll the display down or up. Press key <F1> to skip the brief program summary and position the text on the Usage section directly. Press key <Esc> or <F2> to return to the Status/Usage panel. Press key <X> or click the mouse upon the screen button labelled <eXit> to return to the DOS-prompt command line from either panel. If the program is waiting for keyboard (or mouse input) during the display of the Status/Usage panel, it calls repeatedly the IDLE interrupts of DOS: INT 28h and, if MS-DOS 5 is installed, function 1608h of INT 2Fh. INT 28h allows a potential background activation of (some) other residents whereas INT 2Fh/1608h allows DOS 5 to suspend the program temporarily and transfer control to another program. NOTE: (EGA users only) The default IBM palette attributes are restored if the EGA BIOS fails to store properly the original data. -------------- 4. INSTALLATION The enclosed utility INSTALL.EXE may be used to copy the program files to a user-defined drive and directory, and --if so desired-- to add a command in the CONFIG.SYS file to load the device driver XDISK.SYS, and to add the new directory to the PATH= statememnt in the AUTOEXEC.BAT file. For manual installation, see section USAGE above. INSTALLATION AVOIDANCE In the registered program copy, the installation of XDISK.SYS can be skipped by pressing the <Esc> key before the initialization is completed, e.g. prior to the display of the driver installation banner. <Esc> keypress interrupts the loading until the following query is answered by pressing <Y>es or <N>o: XDISK.SYS: <Esc> pressed ─ Cancel installation? [yn] This avoidance of installation produces no memory penalty under DOS versions 3.30 or higher, but uses some 80 bytes of conventional memory in earlier DOS versions. When XDISK.EXE is executed and identification string for the specified drive is found, the memory segment where the corresponding xDISK driver was loaded is displayed in the Status/Help panel when the keys <F10>+<Alt> are pressed. This segment is preceded by the initials 'UMB' if the driver is installed in upper memory, and by the initials 'LMB' if installed in conventional memory. INSTALLATION ERRORS The following errors fail the installation of the driver: A. Invalid CRC - Driver has been corrupted B. Invalid CPU type - Needs 286/386 or higher CPU C. Invalid DOS version - Needs 2.10 or later D. Failure to detect presence of an EMS manager E. Expanded memory allocation error (EMS code) F. Expanded memory EMM status error (EMS code) G. Expanded memory page frame error (EMS code) See XDISK.MSG for an explanation of driver error messages. --------- SELF-INSTALLATION IN HIGH MEMORY The driver can install itself in the upper memory area (UMA), that is, at RAM addresses between 640 kb and 1024 kb of memory, via switch /H (or its subfunctions /Hn, /H!, and /Hn!). Program releases prior to version 3.10 lack this feature. The allocation of UMA blocks (UMBs) is arbitrated by an XMS manager (XMM) version 2.0 or higher; the XMM must be installed prior to the UMB-loading of the resident. Allocation also requires the remapping of UMA addresses by a UMB provider, when such a task is not implemented by the XMM itself. XMMs require DOS version 3.0 or later. HIMEM.SYS is the XMM distributed with MS-DOS 5; installing this XMM along with an UMB provider (e.g., a 386-specific memory manager such as EMM386. EXE, also distributed with DOS 5), and enabling DOS access to the UMA via the 'DOS=UMB' command, allows DOS 5 to control UMB allocation. Other 386- specific managers, e.g., QEMM386 (Quarterdeck) or 386MAX (Qualitas), are able to provide both UMB remapping and XMS support. Switch /Hn, where A000 ≤ n ≤ FFFF (hexadecimal), allows the specification of a minimum upper-memory limit for the UMB to avoid UMA regions having a very slow access time (or to preserve regions with a fast access time for other utilities that require faster times, such as a disk cache or screen accelerator), or to avoid fragmentation of the UMA when UMB allocation is not controlled by DOS 5, but by the XMM itself. Such a fragmentation may occur when the XMM allocates blocks on a first-fit basis, i.e., the first available UMB having the lowest UMA address is allocated, irrespective of whether or not a (smaller) block matching the requested size is available at a higher UMA address. Unless the size of the available UMBs increases with increasing memory address, first-fit allocation of a small UMB could lead to the breaking of a large UMB into two smaller ones, thus hampering the installation of larger residents in the UMA. When DOS controls the UMB allocation, the program enforces the allocation of the resident block on a best-fit basis when <n> is not specified, that is, all available blocks are searched (by DOS), and the one matching most closely the size requested is allocated. When DOS controls UMB allocation and <n> is specified, UMBs are allocated on a first-fit basis. While this may contribute to UMA fragmentation, it allows for the checking of a minimum memory limit in those cases in which the selection or avoidance of a specific UMA region is more important. Hence, compared to the upper-memory loading provided by the 'DEVICEHIGH=' command of DOS 5.0, or similar services provided by some memory managers, program self-loading into a UMB has several advantages, including: (1) it does not require an initial free block of upper memory of the size of the entire program (as opposed to the size of its resident only), (2) it does allow user control on the selection of the upper-memory block, and (3) it can help reduce UMA fragmentation. NOTE ------------------------------------------------------------------------- The address and size of available UMBs can be obtained with MEM.EXE, when DOS controls UMB allocation, or with the memory manager itself, when this allocation is controlled by 386-specific memory managers. In either case, these data can also be obtained with UMAX.EXE, a UMA mapping utility that is distributed by the author. If memory access time is a critical factor in the selection of the UMBs, detailed access timings are provided by the the utility TIMEM.EXE, which is also distributed by the author. ------------------------------------------------------------------------- HIGH-LOADING VIA MEMORY MANAGERS OR MS-DOS 5 Of course, the resident can also be installed in the UMA via a 386-memory manager or via (UMB-linked) DOS 5.0, provided that there is enough memory for the actual size of the entire program, and any additional memory that may be needed by the loading utility. The driver XDISK.SYS is not distributed as a compressed file. HIGH-DOS MEMORY UPDATING Updating the xDISK driver is accomplished either via DOS-mediated requests to the driver or via a direct updating of the driver by XDISK.EXE (without the intervention of high-DOS memory utilities). --------- DOS ERRORLEVELS XDISK.EXE passes execution status data to DOS. These can be tested in batch files via the ERRORLEVEL command. The following are values for version 3.31 or later: Value Condition ----- -------------------------------------- 255 Cyclical Redundancy Check failure 254 286(386) version executed in non-286(386)+ machine 240 All drives are assigned (reached maximum) 224 All drives are assigned (increased limit) 208 Driver initialization error (command-line load) 192 Driver failed installation (command-line load) 176 Overlay of driver failed (command-line load) 160 Driver filename not given (command-line load) 144 Operating system does not support DOS function 32h 128 Failed to find NUL driver (command-line load) 112 Error during XDISK.SYS load (command-line load) 96 Critical error during load (command-line load) 80 Error during driver unloading 64 Not enough memory 48 Invalid DOS version (1.x, 5.x+, OS/2 DOS 10+) 32 Unknown/Incompatible video card 16 Invalid EMS manager/version 8 /X± switch ignored - Contents cannot be preserved 4 DOS access to driver has been closed 2 Invalid character is password string 1 Resize attempt of Read-Only disk 0 Succesful execution -------------- 5. BASIC TECHNICAL INFORMATION DISK INTERNALS DOS can support several types of disk. Each disk contains information on its capabilities, which is stored on a specific area of the disk. In addition to this information, the disk must contain information necessary to the managing of the files and disk space, which is also stored in a reserved disk area. A DOS-compatible disk consists of 3 reserved areas and a user file area. The reserved areas are the Boot Sector, which contains a table of disk parameters used by DOS to manage disk space, and a bootstrap code to start the operating system; the File Allocation Table (FAT), containing data on file-space usage; and the Root Directory, containing size, location, date, and time information about the files on the disk. The surface of a (physical) disk is laid out as a series of concentric rings, called tracks, which are divided radially into sectors. When storing a file, a cluster is the basic unit of disk allocation used by DOS, and consists of a group of sectors, whose number varies with the disk type; the file is divided among as many sectors as are required to hold it. Whether just one or all of the sectors of a cluster are used, the cluster is marked as in use. In the FAT there is an entry for each cluster on the disk, containing a value that indicates the status of the cluster: reserved for DOS, free, in-use, bad and end of cluster chain. DOS stores cluster information as a cluster chain, in which each cluster points to the next cluster in use. Because the first 2 entries of the FAT are reserved, the first cluster of available disk space in the user file area is cluster number 2. The length of a FAT entry is either 12 or 16 bits, and it depends on the size of the disk in sectors and the cluster size; a 12-bit FAT entry is used until cluster numbers cannot be stored as a 12-bit quantity, which is when there is more than 4,079 clusters. The minimum disk size requiring 16-bit FAT entries can be calculated from: (4079 clusters x [sectors/cluster] x [bytes/sector]) = Disk size Improper FAT length entry due to modification of the above variables produces input/output disk errors; switches /X-, /X+ and /B-n monitor the variables to verify whether disk contents should be preseverved or not. RAM-DISK IDENTIFICATION & DOS VERSION DOS assigns the first available drive letter to a RAM-disk within the default range A to E or, for DOS version 3 or higher, the range A to Z if the command <LASTDRIVE=Z> is included in CONFIG.SYS. Such a letter is shown by XDISK.SYS when using DOS 3.0 or higher, but when using earlier MS-DOS versions. An xDISK RAM-disk can be identified by its volume label and time of creation, and by the OEM identification in the boot sector, all of which are determined by the program version. If executed in an 80286 processor or higher CPU, the date of creation of the RAM-disk is the current date in the CMOS chip; for an 8088/8086 CPU, such date is that of the assembly of the xDISK version. DIRECT DRIVER COMMUNICATION Starting from version 2.52, the device header of each XDISK.SYS installed has the string: xDISK[0]unit:[0]<d>[-1] where the ending delimiter byte [-1] contains the hexadecimal value 0FFh, the null separator bytes [0] contain 0, and the drive designator <d> is the upper case letter assigned to the RAM-disk (MS-DOS 3.0 or higher version) or a null byte (MS-DOS versions earlier than 3.0). The identifying string is used to locate the driver for direct communications between XDISK.EXE and XDISK.SYS. Note that when this string does not contain a designator letter (as when using DOS 2.10), switches /A, /G, /P, /R, and /V can only be assigned to the first XDISK.SYS driver found in memory. When XDISK.EXE is executed, the program searches memory for the corresponding identifying string. If the correct drive is not specified, or the driver has been installed in the upper memory area, the search may extend as high as the first 1 Mb of memory (see below). -------------- 6. IDENTIFICATION IN MEMORY MAP UTILITIES The fact that the xDISK driver can be loaded either via the CONFIG.SYS file or from the DOS command line may lead to some confusion when mapping memory usage, since with some MS-DOS versions other than 5.0, an anomalous mapping of installed drivers is obtained after a DOS command-line loading. The following are partial displays obtained with the memory mapping utility PMAP.EXE (version 2.10, (c) 1986-1991 by The Cove Software Group) after the upper-memory loading of 2 xDISK disks via CONFIG.SYS, followed by a command line loading of a third drive in lower memory, using XDISK.SYS version 3.31 (386+) under COMPAQ DOS 3.31; the access to the UMA was controlled by a 386 specific memory manager that provided the UMBs and implemented the XMS: Device driver information: Name Address Size Strt Intr CHR IOC -------- --------- ------ ---- ---- --- --- NUL 0070:25D8 1599 159F * L: 0BCF:0000 96 0012 0018 * <- 2nd xDISK drive L: K: 0BCB:0000 96 0012 0018 * <- 1st xDISK drive K: Device driver information: Name Address Size Strt Intr CHR IOC -------- --------- ------ ---- ---- --- --- NUL 0070:25D8 1599 159F * M: 1165:0000 0038 0044 * <- 3rd xDISK drive M: L: 0BCF:0000 22880 0012 0018 * <- 2nd xDISK drive L: K: 0BCB:0000 96 0012 0018 * <- 1st xDISK drive K: Notice that after the command-line loading the third disk, the reported size of the 2nd disk, which is only 96 bytes in conventional memory, is increased to about 22kb. This result, which can be obtained with other driver mapping utilities, is harmless and can be safely ignored. ---------------- 7. LICENSE INFORMATION This documentation, programs, and other files distributed in this software package (the "Software") are the copyrighted property of FM de Monasterio (the "Author"), who provides the Software and licenses its use. All rights are reserved. The file XDISK.REG contains a form needed to register this Software. SINGLE USER LICENSE. Upon registration, you are granted a nontransferable license to use this Software in a single computer at a time. The Software may also be transferred to another computer, provided that the Software is used only in one (1) computer at any time; under the license, the Software may NOT be installed on a network server. SITE/15-PCs LICENSE. Upon registration, you are granted a nontransferable license to use this Software in a single site, or a set of sites, provided this Software is not used in more than fifteen (15) computers at any time, and that such computers are located exclusively within the site. Licenses for more machines are available at discounted prices. SOFTWARE BUNDLING LICENSE. Please write to the Author. REFUNDS POLICY. If a problem notified within ninety (90) days of shipping of the registered copy cannot be solved, the registration fee (but not the shipping costs) will be refunded upon receiving a written request with the original diskette(s) enclosed. UPGRADE POLICY. Program upgrades are limited to licensed users. Upgrades within the same major version (e.g. release 4.00 through 4.99) are free of charge when a self-addressed, stamped, 5.25" diskette mailer with a 360-kb kb diskette is included with the request. Other upgrades are charged half the (single-user/site) registration fee. See enclosed file XDISK.UPG. TECHNICAL SUPPORT. A phone number for technical support is made available to site licenses for 100 machines or more; other licensed users must write to the Author who will contact them. U.S. GOVERNMENT INFORMATION The use, duplication, or disclosure by the U.S. Government of the Software is subject to the restricted rights applicable to commercial software that are specified in the subdivision (b.3.ii) of the 'Rights in Technical Data and Computer Software' clause, document DFARS 52.227-7013. The contractor/ manufacturer is FM de Monasterio, P.O. Box 219, Cabin John, MD 20818-0219. ---------------- DISTRIBUTION You may distribute this Software via magnetic and/or electronic means, but you are specifically prohibited from: - Charging fees or asking donations in exchange of or payment for copies of this Software. - Distributing this Software with commercial products without the written, express permission in advance from the author. - Distributing this Software via a for-profit organization or group, either alone or with other software. - Modifying any contents of this Software, including, but not limited to, the copyright notice and this license. The unauthorized copying, decompiling or disassembling of this Software is prohibited. Any other use of this Software is also prohibited without the express, written permission in advance from the author. Latest program releases may be found at the Information Exchange BBS, 202- 433-6639 (703-836-0748 after March 1992), as a compressed archive file. ---------------- WARRANTY DISCLAIMER The Author cannot and does not warrant that any functions contained in the Software will meet your requirements, or that its operations will be error free. The entire risk as to the Software performance or quality, or both, is solely with the user and not the Author. You assume responsibility for the selection of the program to achieve your intended results, and for the installation, use, and results obtained from the Software. The Author makes no warranty, either implied or expressed, including with- out limitation any warranty with respect to this Software documented here, its quality, performance, or fitness for a particular purpose. In no event shall the Author be liable to you for damages, whether direct or indirect, incidental, special, or consequential arising out the use of or any defect in the Software, even if the Author has been advised of the possibility of such damages, or for any claim by any other party. All other warranties of any kind, either express or implied, including but not limited to the implied warranties of merchantability and fitness for a particular purpose, are expressly excluded. LIMITATION OF REMEDIES The information contained in the documentation for the Software is subject to change without notice. The Author's entire liability, and your exclusive remedy shall be: (1) the replacement of an original Software diskette not meeting the above Limited Warranty and which is returned to the Author along with proof of purchase, or (2), if the Author is unable to deliver a replacement diskette which is free of defects, you may terminate the License Agreement by returning this Software and the corresponding license fee will be returned. By using the Software, you acknowledge (1) to have read and understood all parts of this document and (2) to have agreed with and accepted all of its provisions without any reservation. ---------------- Refer all inquiries to: FM de Monasterio P.O. Box 219 Cabin John, MD 20818-0219 USA ┌─────────────────────────────────────────────────────────────┐ │ Trademarked names are the property of the respective owners │ └─────────────────────────────────────────────────────────────┘ [END]