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╒════════════════════════════════════════════╕ │ dAC │ │ Version 2.30.0 │ │ │ │ Copyright (C) 1990-1993 FM de Monasterio │ │ Licensed Material. All rights reserved │ ╘════════════════════════════════════════════╛ CONTENTS 1. SUMMARY 2. REGISTRATION 3. GENERAL INFORMATION 4. INSTALLATION & USAGE 5. INSTALLATION IN UPPER MEMORY 6. BASIC TECHNICAL INFORMATION 7. OPERATION REQUIREMENTS & CONFLICTS 8. COPYRIGHT & LICENSE INFORMATION 9. DISTRIBUTION INFORMATION 1. SUMMARY dAC is a DOS memory-resident alarm clock that displays the time at the DOS prompt when in video text mode. The user can specify the screen attribute, position, and format of the display; a hotkey for toggling the display off or on; and an alarm time and associated bell parameters. The clock is enabled only while DOS is waiting for command-line input (DOS prompt); the hotkey can be used to override the DOS-prompt toggled status. The resident operation can be changed on the fly by executing dAC with new parameters from the DOS prompt (or batch file) or via the DOS enviroment. The dAC resident can also include a tiny, additional module for poking the current date in the keyboard buffer so as to appear at the cursor position as if it had been entered by the user, if the hotkey were pressed when the <Scroll Lock> key is engaged. The resident automatically becomes inactive in BIOS/VESA graphics modes, including WINDOWS, and active again once text mode is resumed. The default time and date formats and the unit separators are selected from the current country DOS information data; these data can be modified by the user. The program requires MS-DOS version 3 or higher (or a compatible operating system) and a Real Time Clock compatible with the IBM AT-standard. It does not interfere with WINDOWS or with any other application in graphics mode. See DAC.NEW for a description of what is new in the current version. 2. REGISTRATION This software is user-supported; the present release, although lacking the options marked by asterisks below, is a complete program. You may test the 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. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ DAC.REG contains a form needed to register the Software +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ See the final part of this documentation for information on the Licensing, Distribution, and Limited Warranty of this software. 3. GENERAL INFORMATION This is a DOS-based program which, after its loading, remains installed in memory until it is unloaded or the machine is rebooted (terminate-and-stay resident). dAC displays the current time on the screen if the video is in a text mode (standard BIOS or VESA video modes), color or monochrome, and while DOS is waiting for command-line input at the DOS prompt. The user can specify the screen position, the video attributes, and the time format of the display; a hotkey combination for toggling the display on or off; and an alarm time and associated bell parameters can also be specified by the user. The clock display is mediated by the system timer tick interrupt, which is a service triggered about every 55 milliseconds. To avoid unnecessary use of the time slices, the resident uses only 1 out of 4 slices to update the time display, if this is needed. Further, the clock display processing is enabled only while DOS is waiting for command-line input (DOS prompt), not only to preserve the screen contents of a foreground application, but also to avoid potential interferences with disk(ette) operations, some of which are system-timer dependent. If desired, the hotkey can be used to override the DOS-prompt toggling, to allow the foreground display of the clock. A number of time and date stamp services are also available. International support is provided for the time and date default formats, as well as unit separators, based on the current DOS country information. Optionally, the dAC resident can include an additional 170-byte module for poking the current date in the keyboard buffer, so to appear at the cursor position as if it had been entered by the user, if the hotkey were pressed when the <Scroll Lock> key is engaged. When this key is enganged, the dAC hotkey does toggle the clock display or or off. Most functions can be enabled or disabled independently. The resident can be updated on the fly by executing the program with new parameters, and it requires less than 0.7 KB of memory. The program can selfload its resident into a block of the upper memory area via an extended memory manager, with or without MS-DOS 5+. The user can specify a minimum upper memory address to select or avoid a given upper memory region. If enabled, the dAC alarm is sounded whether at the command line of DOS or not, i.e., independently of the DOS-prompt toggling of the dAC display. In addition to preserving the screen of foreground applications, the toggling is important to avoid a potential interference with disk(ette) operations, some which are time dependent. In those cases where a clock display may be required during a foreground operation, the hotkey can be used to override the DOS-prompt toggling. Program messages can be redirected via the commands '>' and '>>' of DOS. 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 80x86 processor family. This is needed since the x86 processors differ markedly in instruction execution time and the incorporation of a memory cache in some CPU types affects such time by influencing the speed of instruction fetching and of memory access. A 486 release should be used with a 586 CPU (Pentium) to minimize degradation of performance vis-á-vis code alignment. 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 relatively small differences in the resident size, which is less than 1000 bytes. REQUIREMENTS The program requires MS-DOS version 3 or later, or compatible DOS system, and an IBM-compatible SVGA, VGA, EGA, MCGA/CGA, or MDA video adapter or a HERCULES video card. The time is read from the battery-powered Real Time Clock (RTC) which is present in AT-type or compatible PCs, along with nonvolatile CMOS memory (such as the Motorola MC146818 chip). dAC tests for the presence of the RTC, and will not operate in machines lacking such a device. SAFETY MEASURES Each time it is executed, the program verifies its code integrity through a number of cyclic redundancy checks (CRCs). Program execution is aborted if any check were to fail as such a failure indicates code corruption and the program should not be used for your own protection. The executable program is distributed as a fully encrypted and compressed EXE-type file in order to reduce the possibility of code tampering. NOTE -------------------------------------------------------------------- Because both encryption and compression change the code sequences to different values, it cannot be excluded that these processess might, by chance, yield an encrypted data sequence which triggers a warning from antiviral utilities that merely check disk-stored files against a list of code 'signatures' or instructions. Though all distribution diskettes are scanned with one such utility to avoid the possibility of spurious warnings, the changing nature of these 'signature' lists makes this exclusion difficult. If using these utilities, check the registered distribution diskette before installing the programs in your hard disk, and please contact the vendor (see below) if a spurious warning were triggered. -------------------------------------------------------------------- 4. INSTALLATION & USAGE In the descriptions below, {} enclose context variables, e.g., the number {n}, whereas <> enclose alphanumeric characters or keys, e.g., the letter <n>. 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 statements to the file AUTOEXEC.BAT so that the program is loaded automatically upon booting and to append the user-defined directory to the PATH statement. MANUAL INSTALLATION Alternatively, to install the program manually, add the command {path}DAC [/SWITCH1 ... /SWITCHn] [;comments] to the AUTOEXEC.BAT file, if you wish to have the program installed after booting the system, or simply enter this command from the DOS prompt when you want to use the program. If given, {path} must specify the drive and subdirectory for the file DAC.EXE. Square brackets enclose optional command arguments; [/SWITCH1.../SWITCHn] are program command switches, whereas [;comments] are comments that might be useful to clarify batch file usage. If executed with a null argument (i.e., switches were not specified), the program searches the DOS environment block for a variable with the format DAC=/SWITCH1 ... /SWITCHn, to use these switches as program commands (see switch EV below). If the execution command has null arguments, an environment variable does not exist, and the resident is not yet installed, then the default (i.e., preselected) configuration is used for the installation. If the resident is already installed, and an environment variable does not exist, a null- argument command has no other effects than updating the resident in terms of the video system. The default cases of the various switches are given below. Once installed, the resident can be modified at any time by executing the program with new parameters. If other memory-resident programs were also used, make sure all residents installed are 'well behaved' and pass along the necessary interrupt data (see 'OPERATION REQUIREMENTS & CONFLICTS'). COMMAND SWITCHES These switches allow for the modification of the default (preselected) or of an already selected resident configuration, or the execution of one of the non-resident services provided by the program (e.g. display of a Help panel, adjustment of display brightness, etc). The switches can be specified in any order, and they must be separated by a space, tab, comma, or slash; a dash preceded by space may also be used. They are not case sensitive, e.g., /EV = /Ev = /eV = /ev. Invalid switch specifications may result in an error message or in program cancellation. When parsing the command line, the program converts all switch separators to slashes. Switches consist of 2 letters; when a single letter would be an unambiguous specification only the first switch character is required: for instance, both /U and /UL are recognized as requests to uninstall the resident from memory. Whereas some switches have a single status (e.g., uninstall the resident) others may have more than one status (e.g., a on/off display toggle). The program has built-in (default) values for some switches, values which are used if a new value is not specified when installing the resident. These switch defaults are /BD64/BF440/BN3/HC+/HK+/HKT6/TD+/TS+ Other switch defaults are contigent on the current system status, such as DOS country information (SC, TH, VS), video mode (VP) and video attribute at cursor position (VA). The following switches are recognized: --------------------------------------------------------------------- (*) Asterisks mark options not available in the unregistered copy --------------------------------------------------------------------- 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. See section 'STATUS/USAGE/ HELP PANELS' below. EGA users: The default MS-DOS palette attributes are restored if the EGA BIOS fails to store data in the Parameter Save Area. Old EGAs may store invalid data in this area, resulting in an improper restoration of the video attributes (use the DOS command MODE CO80 to restore the default attributes). * SWITCH AT ~~~~~~~~~ Alarm times are given as hour {h} and, optionally, minute {m}, and second {s}. Only one alarm may be active at any given time, and it occurs every 24 hours at the selected time. Alarm services are BIOS mediated and need a CMOS time/date chip. AT? Display the current alarm status. AT+ (Re-)Enable alarm operation. AT- Disable alarm operation; this is the default condition if a switch argument is not specified. AThh[:mm:ss] Alarm time using a 24-hour format, i.e. {hh}=0-23. The use of {mm} and of {ss} is optional; if not specified, a value of 0 is used. AThh[:mm:ss]x Alarm time using a 12-hour format, i.e. {hh}=1-12. The use of {mm} and of {ss} is optional; if not specified, a value of 0 is used. Use {x}=A[M] or P[M] to indicate ante or post meridian time. Defaults: /AT = /AT+; AThh:mm = /AThh:mm:0; /AThh = /AThh:0:0; no switch on installation = /AT-. NOTE ----------------------------------------------------------------- The time separator <:> varies with DOS country information format in use. The above examples assume USA country information format. ------------------------------------------------------------------ * SWITCH BD ~~~~~~~~~ Alarm bell duration. Use BDn, where {n} is between 1 (shortest) and 128 (longest). Defaults: /BL = /BL64; no switch on installation = /BL64. * SWITCH BF ~~~~~~~~~ Frequency or pitch of alarm bells in cycles/second (Hertz). Use BFn, where {n} is between 25 Hz (low) and 5000 Hz (high). Defaults: /BF = /BF440. * SWITCH BN ~~~~~~~~~ Number of alarm bells. Use BNn, in which {n} is between 1 and 8. Defaults: /BN = /BN3; no switch on installation = /BN3. * SWITCH EV ~~~~~~~~~ When the _initial_ copy of COMMAND.COM is loaded at boot time, it creates a block of memory that will contain the master or global DOS environment. The environment of DOS consists of a number of text-based variables, each variable consisting of a name and an associated string having the format: VARIABLE=string of characters in which the end of the string is marked by a zero byte. The environment contains a series of such variables, and the end of the environment block itself is indicated by an additional zero byte. These variables are used to pass information to and from COMMAND.COM (or a DOS shell replacement), batch files, and application programs, such as the PATH= and the COMSPEC= variables. Switch EV creates or, if it already exists, updates the environment block variable: DAC=/SWITCH1/SWITCH2.../SWITCHn where /SWITCH1.../SWITCHn are the command switches to be implemented when the program is executed from the DOS command line or a batch file without any arguments. Although switch EV itself is incorporated in the variable as well, it is ignored when such variable is used to provide input to the program. (See 'ENVIRONMENT VARIABLE DAC' for more details.) No defaults. SWITCH HK ~~~~~~~~~ Hotkey combination to toggle display on and off. The default combination is <Left-Shift><Ctrl><T>. The hotkey is also used for the date-at-cursor stamp service provided by switch SC (see below). HK? Permit selection of a new hotkey combination including an alphanumeric key, and one or more of the shift keys <Ctrl>, <Alt>, <left-Shift>, and <right-Shift>. HK+ Enable hotkey operation; this is the default condition if a switch argument is not specified. HK- Disable hotkey operation. Can be reenabled with /HK+. * HKxn Select {xn} as the hotkey combination, in which {x} is a alphanumeric character (0-9 or A-Z) only, and {n} is a digit between 4 and 15 only. This digit corresponds to one of the following shifting keys or their sum: 1 = <right-Shift> -------------------------- 2 = <left-Shift> Values higher than 15 or 4 = <Ctrl> lower than 4 are invalid 8 = <Alt> -------------------------- For obvious reasons, <Ctrl> or <Alt>, or both, must be part of a new hot- key combination either in switch HK? or HKxn. If a hotkey other than the default combination is needed routinely, it may be useful to store in the DOS environment the variable 'DAC=/HKxn' (see below). Defaults: /HK = /HK+; no switch on installation = /HK+ /HKT6. * SWITCH LH ~~~~~~~~~ Loads the resident in the Upper Memory Area (UMA), between addresses 640 KB and 1,024 KB of memory; this is the region below the 1-MB boundary of the memory accessible by 086 CPUs, but above the 640-KB hardware barrier of MS-DOS. The switch requires an available upper memory block (UMB) of about 1 KB, which is allocated by the program itself either via a direct XMS request or, if MS-DOS controls UMB allocation (i.e. DOS 5+ linked to the UMA through the command 'dos=umb' in the CONFIG.SYS file), via calls to DOS. Allocation of UMBs requires the presence of an XMS manager (XMM) supporting the UMB services 10h-11h of XMS 2+, and (if the XMM lacks the capability of remapping memory) the presence of an UMB provider. SWITCH LHn A lower upper-memory limit for the UMB loading can also be requested via switch LHn, in which {n} is a four-digit hexadecimal number between A000 (640 KB) and FF00 (1,020 KB), in order to avoid or select specific areas of upper memory. Defaults: Low-memory installation if any error is found during the UMB loading; high-memory installation below lower-address limit if UMBs are not available above such limit. SWITCH QU ~~~~~~~~~ Forces the resident to become quiescent until the next time the program is executed, provided that neither switch QU nor ? is specified at such time. No defaults. SWITCH RC ~~~~~~~~~ Resets the resident gate controlling the clock display at the DOS prompt, in case a forcing of this display is desired. No defaults. * SWITCH SC ~~~~~~~~~ Date stamp-at-cursor. Use SC to add a 170-byte module to the resident that loads the keyboard buffer with the current date stamp (month day, year) if the hotkey combination is pressed while the Scroll Lock is enganged (i.e., the <Scroll Lock> key is toggled on). The stamp is displayed on the screen whenever the next request to read the keyboard via interrupt 16h is issued, and the stamp format is based on the current country DOS information data (mm/dd/yyyy, USA; dd/mm/yyyy, Europe; yyyy/mm/dd, Japan). Switch SC is ignored after the resident is installed. No defaults. SWITCH SH ~~~~~~~~~ Display an 8-character hexadecimal stamp (used by DOS for stamping files), which has a time resolution of 2 seconds or more. No defaults. SWITCH SJ ~~~~~~~~~ Display the current date using the Julian format (number of days since the 1st of January, year). A leap year is defined as a year which is divisible by 4 but not by 100, or is divisible by 400. No defaults. SWITCH ST ~~~~~~~~~ Display the current Date/Time stamp (read from the system timer count area of the BIOS). Uses USA country information format. No defaults. * SWITCH SW ~~~~~~~~~ Stopwatch to measure execution time. Use SW[2]"[path]NAME.EXT [switches]", where <EXT>=COM or EXE; with PS/2 machines use SW2. The file specification must be enclosed by double quotes. To measure the execution time of batch files or DOS internal commands use SW[2]"[path]COMMAND.COM /C [NAME.BAT or DOS command]". No defaults. SWITCH TD ~~~~~~~~~ Toggle clock display on and off from the DOS command line; it also permits to display of the clock outside the normal DOS-prompt display restriction. TD+ Enable clock display. TD- Disable clock display. Defaults: /TD = /TD+; no switch on installation = /TD+. SWITCH TH ~~~~~~~~~ Toggle clock display between 12-hour (1-12) and 24-hour (0-23) time format. TH12 Use a 12-hour format time display. TH24 Use a 24-hour format time display. Default: No switch on installation = Current country information data from the KEYBxx keyboard driver, if one is loaded, or the default country code. SWITCH TS ~~~~~~~~~ Toggle on and off the display of seconds. TS+ Use <hour:minute:second> time format display. TS- Use <hour:minute> time format display. Defaults: /TS = /TS+; no switch on installation = /TS+. SWITCH UL ~~~~~~~~~ Uninstalls the resident code from memory. This request is disregarded if the address of any of the interrupts intercepted by the resident has been modified since the program was installed. The revectoring indicates that another resident has subsequently hooked the same interrupt(s). Thus, the program cannot be uninstalled, because this would leave such interrupt(s) pointing to empty memory, and the program would then crash. The program should be uninstalled only if it is the last resident to have been installed. In practice, however, it can also be uninstalled when any subsequently installed resident intercepts different interrupts; although this increases fragmentation of memory, the resulting "hole" is innocuous and can be used by DOS for other purposes (e.g., an environment block). No defaults. SWITCH VA ~~~~~~~~~ Video attributes of the clock display. VA? Show current video display attributes and allow the selection of new attributes for the display in an interactive manner. VAhh Select new video display attributes from the DOS command line where {hh} is a 2-digit hexadecimal number between 00 and FF, representing the attribute of the background (1st digit), and the attribute of the foreground text (2nd digit): 0 - Black 8 - Gray 1 - Blue 9 - Intense Blue 2 - Green A - Intense Green 3 - Cyan B - Intense Cyan 4 - Red C - Intense Red 5 - Magenta D - Intense Magenta 6 - Brown E - Yellow 7 - White F - Intense White NOTE ------------------------------------------------------ A background video attribute of 8 or higher normally produces a blinking text display. ------------------------------------------------------ Default: No switch on installation = Screen attribute at cursor position. SWITCH VP ~~~~~~~~~ Video coordinates of the clock display. VP? Show the current screen coordinate of the _last_ character of the clock display. Variations of display format (e.g., TH or TS) do not affect the position of the last character. VPc:r Select a new display coordinate from the DOS command line, in which {c} is the column and <r> is the row within the current video mode. The colon between coordinates c:r is mandatory. Default: No switch on installation = Upper right corner of the screen, as based on the current video mode (either standard BIOS, e.g. 80:01, or VESA video mode, e.g. 132:01). * SWITCH VS ~~~~~~~~~ Time units separator. Use /VSx to define the character {x} separating time units in the clock display. Default: No switch on installation = Current country information data from the KEYBxx keyboard driver, if one is loaded, or the default country code. COMMENTS The comments may be added in the command line after the desired switches and must be preceded by a semicolon. Such comments, which may be useful in clarifying batch files, are ignored by the program. Do not use the redirection and pipe characters in the comments since DOS will attempt to implement the implied redirection or pipe request. 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 areas of the screen and clicking either button. The mouse driver state is saved prior to the display, to be restored later, if sufficient memory is available for the panel display.) The STATUS/USAGE panel, which is shown first, describes status information for the resident and its services. If the program has not been installed, pressing key <F3> or <D> shows the default installation parameters. If it is installed, pressing key <F3> or <T> sets the clock alarm to the current time for testing purposes. 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. Press key <F7>, or <X>, or click the mouse upon the screen button labelled <Exit> to return to the DOS-prompt command line. 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 or the key <S> to scroll in a closed loop; alternatively, click the mouse upon the Up/Down arrows at the top right corner of the screen to scroll. Press key <F1> to skip the brief program summary and position the text on the Usage section directly. A beating icon to the left of the preceding USAGE panel controls the speed of screen scrolling of the HELP panel via key <S> or the mouse arrows. By positioning the mouse pointer over the beating heart and clicking the left or right mouse button, the rate of scrolling can be respectively increased or decreased; the scrolling rate can also be changed by clicking the mouse on the icon that becomes visible on the top line of the HELP panel (if the mouse driver is installed). Press key <Esc> or <F2>, or click the mouse upon the rightmost icon at the top left corner of the screen, to return to the Status/Usage panel. Press key <F7> or <X>, or click the mouse upon the leftmost icon, to exit to the DOS-prompt command line. THE ENVIRONMENT VARIABLE DAC When the program is executed from the command line of DOS or a batch file without an argument, it searches the DOS environment block for a variable named 'DAC' having the format: DAC=/SWITCH1/SWITCH2 .... /SWITCHn Up to 128 characters are allowed after the equal sign. This string can be incorporated to the environment block via the 'SET' command of DOS or via switch EV of this program (see above). The variable can be used to specify a program default configuration which can be restored just by executing the program without an argument after a temporary change of parameters. While the SET command modifies the current DOS environment block, whether it is the global or a local one, switch EV only modifies the global block (even when the program is executed via a secondary COMMAND.COM, as in the case of shelling out to DOS from an application). Notice that the local environment block is only a copy of the global block and lacks sufficient room to increase significantly the length of a variable, and that changes made to a local environment are not inherited by the global one. When searching for the environment variable, the program uses the current DOS environment block, whether it is the global or a local one. 5. INSTALLATION IN UPPER MEMORY This section describes in more detail aspects of the active (i.e., self- loading) or passive (e.g. via DOS LOADHIGH) installation of the resident in the upper memory region. UMA SELF-LOADING The utility can self-install the resident in the upper memory area (UMA), that is, RAM addresses between 640 KB and 1,024 KB, via switch LH (or its subfunction LHn). 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. The XMM HIMEM.SYS and the UMB-provider EMM386.EXE are distributed with MS DOS 5+. The allocation of UMBs is controlled by DOS when these 2 drivers are installed, and the command 'dos=umb' is added to the CONFIG.SYS file. With DR-DOS 6+, UMB remapping and XMS support are provided by EMM386.SYS. Other 386-specific memory managers, of course, also provide UMB remapping and XMS support. All XMMs require MS-DOS version 3 or later. Switch LHn, 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 MS-DOS 5+, but by the XMM itself. The 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 leads to the breaking of large UMA blocks into smaller ones, thus hampering the UMB installation of larger residents. If MS-DOS 5+ controls 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 LH command of MS-DOS 5+, the HILOAD command of DR-DOS 5+, or a similar service provided by other memory managers, self-loading into a UMB has several advantages, including: (1) it does not require an initial free UMB 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 via the memory manager itself (when the allocation is controlled by 386-specific memory managers. In either case, such data can also be obtained with UMAX.EXE, a UMA mapping utility that is distributed by the author. ------------------------------------------------------------------- UMA LOADING VIA MEMORY MANAGERS, DR-DOS 5+, or MS-DOS 5+ The resident can also be installed in the UMA via a 386-memory manager or DR-DOS 5+/MS-DOS 5+ commands (e.g., HILOAD, LH, etc), provided that there is a sufficiently large, free UMB for the actual size of the entire file, and any for additional memory that may be required by the loading service itself. Please note that, to minimize disk storage, the program is distributed as a compressed EXE file that expands on execution by a factor of 2 or less. Thus, the difference between the actual size upon loading and the nominal directory size may create conflicts with UMA-loading services that do not measure actual size: If the available upper memory were smaller than that required by the decompressed file but larger than the nominal (directory) size, such service would attempt to load the compressed file. Of course, the subsequent file decompression would overwrite the adjacent memory and likely crash the memory manager or DOS! When attempting to load the resident in a UMB via a memory manager or DOS 5+, do NOT request in the same command line switches that result in panel displays. These displays require an additional 8,000 bytes of *adjacent* free memory, and the free RAM measuring procedure used by the program can be negated by UMA-loading services that do not update the program segment prefix (PSP) of the program being loaded. Such switches are VA?, HK?, and /?. IDENTIFICATION IN MEMORY MAPS If the resident has been loaded in lower conventional memory, the program can be identified by name in usage maps yielded by various memory mapping utilities. Although the program sheds its own copy of the environment at installation time (to minimize the resident size), the name dAC x.yy.z will appear in the command line listing for the resident, irrespective of the actual content of the DOS command line at the time of loading; x.yy.z are the ASCII major.minor.revision version numbers, e.g., 2.30.0. However, when UMB loading is mediated by the XMS directly (e.g., extended memory manager and DOS versions 2-4, or MS-DOS 5+ not linked to the upper memory) and the resident is selfloaded via switch LH, many memory mapping programs do not list the allocated block, or lump it with other allocated blocks, or fail to reveal the name of the resident. If the UMB allocation is controlled by MS-DOS 5+, the UMB resident can be identified with some mapping utilities (e.g., MEM.EXE of MS-DOS) although it is listed as "Data" instead of "Program." 6. TECHNICAL INFORMATION INTERRUPTS Whenever certain conditions occur, either within a program or the system, it becomes necessary for the processor to interrupt its current operation and execute one of a group of special routines. The action that triggers the execution of such a routine is referred to as an interrupt; there are internal interrupts, in response to a state of the CPU or an instruction, and external interrupts, caused by signals sent to the CPU from elsewhere in the system. When the program is waiting for keyboard (or mouse) user input during its Status/Usage/Help display, it invokes repeatedly the 'idle' interrupts of DOS: INT 28h and, if running under MS-DOS 5+, function 1680h of INT 2Fh, if this function indicates that it can process program suspension. INT 28h permits potential background activation of (some) other residents while INT 2Fh/1680h permits MS-DOS 5+ to suspend the program temporarily, and transfer control to another program. The program resident intercepts the following interrupts: INT 09h - Hardware Keyboard INT 16h - BIOS Keyboard INT 10h - BIOS Video INT 1Ch - BIOS System Timer INT 21h - DOS System Services INT 2Fh - DOS Multiplex Services The resident monitors interrupt 21h and 2Fh to detect when DOS is waiting to read the command-line user input, i.e., if the foreground operation is at the DOS prompt, to open or close the clock display gate. The interrupt thus gating the clock display is identified on the Stats/Usage panel. Interrupt 21h is used to toggle the clock display for MS-DOS, PC-DOS, and MS-based OEM DOSes version 4 or earlier, and DR-DOS version 6 or earlier. For MS-DOS and PC-DOS version 5 or later, interrupt 2Fh is used if DOSKEY or any DOS command-line editor supporting function 4810h of interrupt 2Fh ('Read Command Line' function of DOSKEY) is installed; else interrupt 21h is used. See OPERATION REQUIREMENTS & CONFLICTS below when using DOS 5+. Although there are some applications that use the same interrupt services to receive user input for their operations as DOS, the dCA clock will not be displayed during these applications unless the buffer input parameters match those of DOS at its command line. INSTALLATION CHECK Interrupt 2Fh is also used by this program to determine if its resident is already installed via the following INT-2Fh call, Registers at call: BX = 'dA' API signature AH = 'C' API signature AL = 0 Installation check request Return registers if successful: AX = ES Segment address of paragraph aligned TSR BX = NOT 'dA' API countersignature and ES:[81h] -> Verification signature 'dAC x.yy.z' where x.yy.z are the ASCII major.minor.revision version numbers. DOS ERRORLEVELS Upon completion, the program passes an errorlevel value which can be used to check (via ERRORLEVEL commands in a batch file) the outcome of program execution. The following errorlevels may be passed: Value Nature of Error ----- ------------------------------------ 255 Cyclical redundancy check failure 255 CPU type cannot execute 286/386/486 version 255 Invalid DOS version 64 XMM not installed or XMS error in UMB load 32 Error in update of environment variable 16 Invalid hotkey combination 8 Unknown video adapter 4 Unable to uninstall resident 2 Invalid switch request 1 User <CTRL-BREAK> keypress 0 Successful execution Some conditions generating errorlevels 1 through 128 may be additive, and the resulting error value may represent more than a single error. CMOS STORAGE LAYOUT The 64-byte, nonvolatile CMOS memory (Motorola MC146818 chip) of AT-class and compatible machines contains information on the current time and date as well as hardware configuration. Addresses 16 through 32 are protected by a 16-bit checksum. RTC registers: Other registers: 0 Seconds (BCD) 14 Diagnostics status byte 1 Alarm on seconds (BCD) 15 Shutdown status byte 2 Minutes (BCD) 16 Diskette drive type 3 Alarm on minutes (BCD) 17 Reserved 4 Hours (BCD) 18 Hard disk drive type 5 Alarm on hours (BCD) 19 Reserved 6 Day of week (Sunday=0) 20 Equipment byte 7 Day of month (BCD) 21-22 Base memory size 8 Month (BCD) 23-24 Extended RAM above 1MB 9 Last 2 digits year (BCD) 25 Disk 1 type (if > 15) 26 Disk 2 type (if > 15) 10 RTC status register A 27-32 Reserved 11 RTC status register B 33-45 Reserved 12 RTC status register C 46-47 Checksum CMOS addr 16h-32 13 RTC status register D 48-49 Extended memory above 1MB 50 Current century (BCD) 51 Miscellaneous information 52-63 Reserved 7. OPERATION REQUIREMENTS & CONFLICTS The resident will not operate properly if access to the interrupts listed above is denied by another program or resident. This can occur with some ill-behaved programs which take over the interrupts and fail to chain the information to other utilities tapping the same interrupts (see TECHNICAL INFORMATION). NOTE -------------------------------------------------------------------- dAC must be installed AFTER installing DOSKEY or any similar command line editor, as otherwise the clock will not be displayed during the DOS prompt unless it is toggled on via the dAC hotkey (in which case the clock display will not limited to the DOS-prompt). -------------------------------------------------------------------- This program is not compatible with Microsft WINDOWS. Through monitoring of the video mode, the time display and the hotkey access of the resident become inactive when graphics-mode based programs, such as WINDOWS, start up and become active again when text mode is restored. If you encounter conflicts with a given text-mode foreground application, these may be avoided by loading the application via a batch file with the following commands: @Echo Off ... [path]DAC /TD-/HK-/QU ; clock inactive <application> [path]DAC /TD+/HK+ ; clock active ... 8. COPYRIGHT & 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 Software is not sold. A license fee is required to use this Software. This license does not transfer to you either the ownership of or the title to the Software, which remain the property of the Author. A form required to license the Software is provided in the enclosed file DAC.REG. SINGLE USER LICENSE. Grants you use of this Software in a single computer at a time; the Software may be transferred to another computer, as long as it is used only in 1 computer at any time; under the license, the Software may NOT be installed on a network server. SITE/15-PCs LICENSE. Grants you use of this Software in a sigle site or a set of sites, as long as the Software is not used in more than 15 machines at a time, and that such machines 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 diskette is included with the request. Other upgrades are charged half the (single-user/site) registration fee. See the enclosed file DAC.UPG. U.S. GOVERNMENT INFORMATION The Software is Commercial Computer Software under the Federal Acquisition Regulations of the U.S. government and the Agency Supplements to them. The Software is provided to the Federal Government and its agencies only under the Restricted Rights Provisions of the above noted regulations applicable to commercial software developed at private expense, and not in the public domain. The use, duplication, or disclosure of the Software by the Federal Government or its agencies is subject to the restrictions set forth in the subdivision (c.1.ii) of the Rights in Technical Data and Computer Software clause at DFARS 252.227-7013 (October 1988) and FAR 52.227-19 (June 1987). 9. DISTRIBUTION INFORMATION You may distribute the Software, 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. - Changing any of the contents of this Software including the copyright notice and license information. You may not disassemble or otherwise reverse engineer the Software. Other uses of the Software are prohibited without a written authorization signed by the Author. Latest program releases may be found at the Information Exchange BBS (703) 836-0748, as a compressed archive file. WARRANTY DISCLAIMER FOR UNREGISTERED COPIES The information contained in the documentation for the Software is subject to change without notice. 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 Software 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. 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 terms and provisions without any reservation. For information on the terms of the Limited Warranty for licensed Software copies or any other information on this program, please write to: FM de Monasterio P.O. Box 219 Cabin John, MD 20818-0219 USA ┌─────────────────────────────────────────────────────────────┐ │ Trademarked names are the property of the respective owners │ └─────────────────────────────────────────────────────────────┘ [end]