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┌─────────────────────────────────────────────────────────────┐ │ Trademarked names are the property of the respective owners │ └─────────────────────────────────────────────────────────────┘ BLANKs Copyright (c) 1988-1991 by FM de Monasterio Licensed Material - All rights reserved Release 4.00 SUMMARY BLANKs is a DOS-based, resident utility which blanks the screen after a selectable interval without a keypress. Intervals as short as 1 minute or as long as 60 minutes can be selected. Selecting 0 minutes disables screen blanking; blanking can be reenabled by a subsequent execution of the program. The utility also offers the option of parking hard-disk(s) heads at the time of blanking, of blanking the screen at the press of a (selectable) hot-key combination, and the use of a password to unblank the (manually blanked) screen. See BLANKS.NEW for a description of what is new in the current version. BLANKs is a (terminate-and-stay) resident program which can be executed repeatedly to change its parameters without yielding multiple copies to memory. It consists of a resident component, that contains the code for video blanking/unblanking and for parking the disk, which occupies less than 1 kb of RAM, and a non-resident component, that loads the resident component, communicates with the resident on further program executions and provides other ancillary video services. BLANKs is compatible with DOS version 2.0 through 5.0. 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. -------------------------------------------------------------------------- BLANKS.REG contains a form needed to register or upgrade this 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 The video blanking is obtained by direct commands to the hardware (video controller) to turn off/on the video signal. This is a fast method that operates successfully in the IBM PC/XT, PC/AT and in some IBM compatible computers installed with MDA, CGA, EGA, VGA, and HERCULES video adapters or with IBM-compatible adapters from other manufacturers. Actually, the blanking/unblanking of the video signal was used by the original PC BIOS during some CGA video services. Starting with BLANKs version 3.34, however, blanking of HERCULES adapter cards (HGC, HGC+, InColor) is based on a zero-row display method, kindly made available by E.C. Raedecker, which preserves the current video mode (text or 720 x 348 graphics) of the adapter, except during CGA emulation (see switch /A). NOTICE The program may not work in some nonIBM microcomputers and it ------ should not be used with other video adapter types unless they are compatible with the IBM adapter(s) at the register level. Blanking occurs as a result of keyboard and BIOS video inactivity within a selectable time interval (of between 1 and 60 minutes), or by pressing a selectable hotkey (<Ctrl-B> in the distributed version). Once blanking has occurred, press any key to unblank the screen; a <Shift> keypress is especially useful for this purpose. BLANKs can be executed repeatedly to modify resident parameters, without resulting in multiple copies to memory. The resident part uses about 800 bytes of memory. BLANKs parameters can be specified from the DOS prompt or via the environment string 'BLANKS' (see below). The noncritical messages, i.e. successful or uneventful operation, can be redirected to the NUL: device (bit bucket) by the DOS redirection command '> NUL.' Critical messages such as operation failures, however, cannot be redirected by DOS commands, and are always displayed (unless the "StdErr" handle processing of the console output has been modified). The program performs a cyclic redundancy check every time it is executed. If the CRC fails, the program aborts execution as CRC failures indicate a modification of the code, and the program should not be used for your own protection. 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 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 resident size. ----------------- 2. USAGE From the DOS command line or from a batch file, BLANKs is installed (or, when already installed, modified) by the command: BLANKs [t] [/switches] [;comments] Where: A. INTERVAL [t] Timed blanking interval (minutes). This is the interval that the program waits before blanking the screen in the absence of keyboard, video (BIOS mediated), or mouse (INT-33h mediated) activity. Valid selections are 0 or a decimal number in the range 1 to 60. Selecting an interval of zero minute disables TIMED blanking; the selection of an interval larger than 60 defaults to 60 minutes or to the value (within the 1-60 range) of the first 2 digits of selections with more than 2 digits. Typing the letter <T> instead of a number yields a 1-second interval for test purposes (see below key <F2> in Status/Usage/Help panel). Defaults: Null interval = 3 minutes; this default can be changed via an environment variable (see below). ----------------- B. Switches to modify the default parameters can be entered from: (1) The DOS command line (or a batch file) (2) An environment variable with the format 'BLANKS=/SWITCH1.../SWITCHn' Switches can be given in any order and any character between space (ASCII 32) and slash (ASCII 47) can be used as a switch delimiter. The switches are not case sensitive and can be entered in any order; an invalid switch specification aborts program execution. (Starting with version 3.17, the switch /C is no longer recognized as a program cloning request.) ------------------------------------------------------------------------- Asterisks (*) mark items available only in registered program copies ------------------------------------------------------------------------- SWITCH /Ax Forces configuration to a specified video adapter. Switch /A bypasses the automatic configuration of BLANKs for the adapter detected at the time of each execution. Valid specifications: /AM MDA configuration: IBM Monochrome Display Adapter and, in text mode only, HERCULES adapters HGC, HGC+, InColor etc. The MDA configuration does not restore a graphics mode in the HERCULES card. Uses and restores bit 3 of video port 3B8h, but forces bits 7 and 1 to 0. /AH HGA configuration: HERCULES adapters (HGC, HGC+, InColor) in text or graphics mode, but not in CGA emulation. Uses and restores register 6 of video port 3B5h. /AC CGA configuration: IBM Color Graphics Adapter, MultiColor Graphics Array [MCGA], and compatible adapters. Uses and restores bits 0-3 of port 3D9h and bit 3 of port 3D8h. /AE EGA configuration: IBM Enhanced Graphics Adapter and EGA- compatible cards. Resets video ports 3BAh and 3DAh. Uses and restores bit 5 of port 3C0h. /AV VGA configuration: IBM Video Graphics Array and compatible adapters. Uses video port 3C4h, and uses and restores bit 5 of port 3C5h. /A- Ignore prior forced configuration. Uses the configuration selected by BLANKs for the adapter detected at the time of (each) execution. Switch /A is useful if the video adapter type is not identified properly; it does not need to be selected unless you want to modify the settings of the program (read the above notice on adapter compatibility). BLANKs (release 3.15 or later) assumes that a CGA whose ROM BIOS contains the letters 'COMPAQ' is a monochrome COMPAQ card; if you wish to override this assumption, switch /AC forces a CGA color configuration. -------- SWITCH /Dn Adjusts brightness of the display (VGA only). The brightness change step is specified by the sign and value of number <n> ranging from -63 to +63. /D-n (for 0 < n < 64): Decrease the brightness of the screen, reducing the contrast of the display. /D+n (for 0 < n < 64): Increase the brightness of the screen, reducing the saturation of the display. /D0 Restore screen to its original brightness as dictated by the settings of the monitor. Clears the screen. Defaults: /D = /D-2, /D1 = /D-1. Brightness changes are additive. Repeated use of the switch or the use of large step numbers yields unreadable displays; use /D0 to restore display contrast. (Switch /D is a sticky parameter, as brightness changes remain in effect even if BLANKs is made quiescent or uninstalled.) -------- * SWITCH /E Creates/updates the environment block variable BLANKS=/SWITCH1.../SWITCHn in which SWITCH1...SWITCHn are the switches to be implemented when BLANKs is executed from the DOS command line without any argument. Although the switch itself is incorporated in the variable as well, it is ignored when BLANKs uses the environment variable as input. See section INSTALLATION, for more details. No defaults. -------- * SWITCH /H Loads the resident in high memory between 640 and 1024 kb, i.e. below the 1 Mb boundary of conventional RAM but above the RAM area whose allocation is always controlled by DOS. It requires an available upper memory block (UMB) of about .8 kb, which is allocated by the program itself either via direct XMS requests or, when DOS controls UMB allocations (i.e., DOS 5.0+ configured under the command DOS=UMB), via DOS calls. The UMB allocation requires an XMS manager implementing the UMB functions 10h and 11h of the XMS version 2.0 or higher, and (if such a manager lacks the capability of remapping memory) presence of an UMB provider. * SWITCH /Hn Optionally, a minimum upper-memory limit for the UMB can be specified via switch /Hn, in which <n> is a four-digit, hexadecimal number between A000 (640 kb) and FFFF (1024 kb), in order to avoid or select specific regions of the Upper Memory Area. * SWITCH /Hn, /Hn@ A (lower-memory) marker can also be installed along with the UMB resident via switch /H@ or /Hn@. This marker uses 144 bytes of lower conventional memory; it can be identified in some memory mapping utilities by the name <BLANKs @ UMB>, and is released from memory when BLANKs is uninstalled. The marker may be used as a reminder that the resident is loaded in upper memory, or to help locate the upper-memory installation address with some mapping programs or to avoid a potential removal conflict if installation of lower-memory and upper-memory residents is interspersed. (See section INSTALLATION, for more details.) Defaults: Low-memory installation if errors are found during UMB loading; upper-memory installation below the specified lower limit if UMBs are not available above such limit. -------- SWITCH /K±?xn Hotkey switch. In addition to timed screen blanking, BLANKs allows manual blanking of the video by pressing hotkey combination. The default hotkey combination is <Ctrl-B> in the distributed version of the program, but it can be changed with this switch in the case of a key-assignment conflict. Once the screen has been blanked via the hotkey (manual blanking), it can only be unblanked by pressing any key. BLANKs erases the hotkey from the keyboard buffer so it is not displayed. However, a program executed after BLANKs is loaded could save the hotkey. This is what happens, for example, with some word processors in which the hotkey needs to be erased from the text. /K+ Enable hotkey operation; this is the default condition if an switch argument is not specified (/K = /K+). /K- Disable hotkey operation. Can be reenabled with /K+. * /K? Permit selection of a new hotkey combination including an alphanumeric key, and one or more of the shift keys <Ctrl>, <Alt>, <lt-Shift>, and <rt-Shift>. * /Kxn Select <xn> as the hotkey combination, in which <x> is a pure alphanumeric character (0-9 or A-Z), 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 /K? or /Kxn. If a hotkey other than the default combination is needed routinely, it may be useful to store in the DOS environment the variable 'BLANKS=/Kxn' (see INSTALLATION section). -------- * SWITCH /M± Enables/disables the monitoring of video activity mediated by a Mouse via interrupt-33h calls. When enabled, switch /M avoids the timed blanking of the screen when mouse activity is detected. Note that switch /M does not unblank the screen after manual blanking via the hotkey combination. * /M+ Enable mouse monitoring; can be disabled with /M[-]. * /M- Disable mouse monitoring; this is the default condition if an argument is not specified at the time of resident installation. Defaults: /M = /M- NOTE: The mouse activity of some application programs is not mediated via interrupt 33h, but by direct commands; thus, BLANKs will not detect mouse activity and the screen will be blanked. NOTE: There are mouse drivers that can crash the machine if interrupt 33h is found to be in use at the time of the driver installation; if you have such a driver and would rather not load it prior to BLANKs, then you must specify switch /M- at the time of installing BLANKs. -------- * SWITCH /P± Enables/disables the parking of the hard disk(s) upon the manual or timed blanking of the screen. Moves the disk head to the highest disk cylinder for each physical disk that can be accessed via interrupt-13h calls (BIOS disk services). Parking is inhibited when BIOS-mediated disk or diskette activity is in progress at the time of blanking. * /P+ Enable hard disk parking; this is the default condition if an argument is not specified at the time of resident installation. * /P- Disable disk parking. (Can be reenabled with /P[+].) Defaults: /P = /P+ If BLANKs is installed in a machine lacking hard disks, parking should be disabled at the time of installation, as a parking attempt may crash some machines with poorly designed BIOSes. NOTE: Disk-parking-upon-blanking is not available in a special version of the program for diskless machines to avoid potential conflicts. -------- SWITCH /Q Disables timed blanking. The switch has the same effect as specifying an interval of 0 minutes for the interval option [t]; it does not affect the manual blanking via the hotkey combination. No defaults. -------- SWITCH /U 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). -------- * SWITCH /W±?x The switch controls password-mediated unblanking. A selected sequence of 1 to 15 non-shifted, alphanumeric characters, followed by a <right-Shift> keypress, must be pressed in correct sequence to unblank the screen after a MANUAL blanking. Rebooting via <Ctrl-Alt-Del> is inhibited. * /Wx Specify the password from the DOS command line, which <x> is a string of 1 to 15 nonshifted, pure alphanumeric (0-9 a-z) characters. /W? Request to specify a new password of up to 15 nonshifted, pure alphanumeric characters. After these characters have been typed, press <ENTER> to make this password resident; press <Esc> to avoid changing the password or press <Ctrl Break> to quit to DOS. The typed characters can be erased with the <Backspace> key. NOTE: If <Enter> is pressed before any valid character is typed, the unblanking of the manual blanking of the video will occur only after pressing the <Right-Shift> key. * /W- Disable password unblanking. * /W+ Re-enable use of the resident password (if a password had not been loaded, the video will unblank only when <Right- Shift> is pressed). Defaults: /W = /W+. NOTE: Even when enabled, the password is not needed to unblank the screen after a TIMED blanking. -------- SWITCH /? Displays the Status/Usage/Help panel(s), which provide information on the current program status and settings as well as a summary of the commands. More detailed syntax information is displayed by pressing key <F1> or <H> (except in a special release of BLANKs for diskless machines). Press key <Esc> or <F2> to return to the previous display. If the program has not been installed, pressing key <F2> or <S> shows the default loading parameters. If it is installed, pressing key <F2> or <T> yields a 1-sec blanking interval for test purposes; the original interval is restored after the screen in unblanked by a keypress. From any panel, press key <F7> or <X> to return to the DOS prompt. Mouse support is also provided for point-and-click key selections. During the display of the Help/Syntax/Status panels, the BLANKs resident ignores Mouse activity via interrupt 33h. If this switch is requested and a VGA/EGA adapter is present, the program stores the contents of the video palette registers prior to asserting its own palette for the Status/Usage/Help display. ---------------- C. 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. ------------------------------------------------------------------------------ 3. INSTALLATION DIRECT UPPER-MEMORY AREA LOADING The utility can self-install the resident in the upper memory area (UMA), that is, RAM addresses between 640 kb and 1024 kb of conventional memory, via switch /H (or its subfunctions /Hn, /H@, and /Hn@). Program releases prior to version 3.20 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. The XMM HIMEM.SYS and the UMB-provider EMM386.EXE are distributed with MS DOS 5.0; 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. Of course, other 386-specific memory managers, such as 386MAX or QEMM386, 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 leads to the breaking of large UMA blocks into smaller ones, thus hampering the UMB installation of larger residents. 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 installation provided by the LOADHIGH 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. HIGH-LOADING VIA 386-MEMORY MANAGERS OR 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. To minimize disk storage, the program is distributed as a compressed file that expands upon its execution. The difference between the actual loaded size and the nominal directory size may create conflicts with high-memory loading programs that fail to measure the actual size: When the available high memory is not sufficient to permit the file expansion, but is larger than the nominal directory size, such programs will load the (compressed) utility. The subsequent expansion will then overwrite adjacent memory and likely crash the memory manager or DOS. The program expands by a factor of about 1.33. Notice that when switches /?, /K?, and /W? have been selected, the execution requires an additional 4,800 bytes of available RAM. UPPER-MEMORY UPDATING When the program has been loaded in the upper memory, it does not require a high-memory loading utility to update its resident, and all updates can be made by executing the program from the DOS-command line. This obviates the cumbersome restriction (of some memory systems) of having to maintain a pool of free upper memory simply to load the entire program to update a small resident. Program releases prior to version 3.00 lack this feature. UPPER-MEMORY DEALLOCATION If the deallocation of the resident is requested (switch /U) from the DOS command line (as opposed to via an upper-memory loading utility), removal of the resident is implemented, even if it was installed in the UMA. The confirmation request of versions 3.00 to 3.16 is no longer required. If deallocation is requested via an upper-memory loading utility, some of of these utilities warn that a "resident installation has failed." Such a warning is harmless and may be ignored. THE ENVIRONMENT VARIABLE 'BLANKS' 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 having the format: BLANKS=/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 /E of this program (see below). Program releases prior to version 3.14 lack this feature. While the SET command modifies the current DOS environment block, whether it is the global or a local one, switch /E 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. The variable can be used to specify a BLANKs default configuration (e.g., /K+/P-/W-/KB8), which can be restored just by executing BLANKs without an argument after a temporary change of parameters. An especially important use of the 'BLANKS' variable (particularly since the removal of switch /C in version 3.17) is to change the hotkey when the default key combination conflicts with that of a foreground application. 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 BLANKs n.nn 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; <n.nn> represents the program revision number (version). Program releases prior to BLANKs 2.20 lack this feature. If the resident is loaded in upper memory when UMB allocation is mediated by the XMS manager directly (e.g. extended memory manager and DOS version 2 to 4, or DOS 5 not linked to the UMA), however, most memory maps do not list the allocated UMB, lump it with other allocated UMBs, or do not show the name of the resident. If UMB allocation is controlled by DOS version 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." Other mapping utilities can identify the UMB resident when its associated lower-memory marker is also loaded (see switch /H@). Program releases prior to BLANKs 4.00 lack this feature. ------------------------------------------------------------------------------ 4. TECHNICAL INFORMATION The program intercepts several software or hardware interrupts: INT 08h - Hardware system timer INT 09h - Keyboard INT 10h - BIOS video services INT 13h - BIOS disk services INT 33h - (Microsoft/Logitech) Mouse services A brief description of these interrupts is given below: INT 8h is issued 18.2 times per second to update the time-of-the-day BIOS counter. Hence, the timer interrupt service must operate within a period of less than about 55 ms, including the overhead imposed by DOS and other programs hooking INT 8h. To reduce overhead, BLANKs uses direct commands to the hardware, which are issued after the original interrupt service is completed. INT 9h is issued when any key on the keyboard is pressed or released. If the hotkey is enabled (switch /K+), the screen is blanked when the hotkey is pressed. The hotkey code is removed from the keyboard buffer; the key code for the keypress that unblanks the screen is removed from the buffer as well (version 3.12+), to allow unconstrained unblanking with any key. INT 10h implements BIOS video services. The screen blanking is suppressed during video activity, but this activity does not unblank the screen once blanking has occurred. Due to the monitoring, video speed is decreased by a very small percentage. INT 13h implements the BIOS disk services. If disk-parking-upon-blanking is enabled (switch /P+), such parking is inhibited during BIOS disk(ette) activity. NOTE: Interrupt 13h is not intercepted in a special version of BLANKs for computers lacking hard disks; this version is smaller than the standard versions by ca. 100 bytes in the resident (and several kilobytes in the nonresident) part. INT 33h (not used by DOS or the BIOS) is used in the (Microsoft/Logitech) implementation of calls to the Mouse driver. This interrupt is claimed by the Mouse driver during its initialization, and it is used by most mouse- aware programs. BYPASSING INTERRUPTS BLANKs bypasses interrupt 8 when a blanking interval of 0 minute has been selected (see below). Interrupt 9 is bypassed only when an interval of 0 minute and switch /K- (see above) have been selected. When switch /K- has been selected along with a nonzero time interval, only the hotkey service of interrupt 9 is bypassed. The BIOS interrupt 10h (video) and 13h (disk) cannot be bypassed by any of the switches, while the (Microsoft/Logitech) Mouse interrupt 33h can be bypassed by switch /M-. Hence, the two interrupt activities of BLANKs are bypassed by the "0 /K-" selection; this may be of use in case of testing potential conflicts with other resident programs. 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+ version 128 XMM not installed or XMS error in UMB load 64 Error in update of environment variable 32 Invalid password format 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. Program releases prior to BLANKs 2.40 lack this feature. ------------------------------------------------------------------------------ 5. OPERATION REQUIREMENTS & CONFLICTS BLANKs will fail to operate properly when access to interrupts 8 and 9 is denied by another program or resident loaded after BLANKs. This can occur with ill-behaved programs that take over the interrupts and fail to chain the information to those other utilities tapping the same interrupts (see TECHNICAL INFORMATION section), such as some WYSIWYG word processors, GUI systems, etc. In particular, if access to interrupt 9 is denied, keyboard activity will fail to unblank a blanked screen; when testing for incompatibilities with a given program, make sure that programs voiding the manual blanking when <Ctrl-B> is pressed, will permit video unblanking after a timed blanking. Programs that deny access to both interrupt 8 and 9 are less of a problem as neither manual nor timed blanking is likely to be allowed. Otherwise, you will need to inactivate BLANKs with the command <BLANKS 0 /K-> before executing an ill-behaved program or application. To monitor interrupt 33h, BLANKs must be installed after the mouse device driver, as otherwise this driver will not allow access to this interrupt. Be aware that some drivers for a well known mouse can crash the system if interrupt 33h is in use at the time of installing the driver; the problem does not seem to occur with other drivers. Since the BIOS video services are comparatively slow, many programs write directly to video memory instead of using the BIOS services. Because such video writes are not detected by BLANKs, screen blanking may occur during during the video activity of such programs. Similarly, any mouse activity implemented by commands that bypass interrupt 33h will not avoid blanking of the screen (as in the case of some desktop publishing programs). ------------------------------------------------------------------------------ 6. LICENSING 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 BLANKS.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 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. 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 2.00 through 2.99) are free of charge if a self-addressed, stamped diskette mailer with a formatted, 360- kb diskette is included with the request. Other upgrades are charged half the (single-user/site) registration fee. 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, USA. ---------------- 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 (2400+ baud). TECHNICAL PROBLEMS If you encounter problems when using the Software (which can be replicated in the absence of other resident utilities), please write to the Author at the address above providing your name and address, program version number, machine model and configuration, and a description of the problem(s). When feasible, corrections for such problems may be incorporated in new program releases. Technical support is limited to registered users; correspondence from nonregistered users may not be answered. ---------------- 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 ------------------------------------------------------------------------------ [END]