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┌───────────────────────────────────────┐ │▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ QBASIX 2 ▒▒▒▒▒▒▒▒▒▒▒▒▒▒│ ├───────────────────────────────────────┤ │ QBASIc eXtender │ │ version 2 │ │ an external library for QBasic │ ├───────────────────────────────────────┤ │ Description of routines and functions │ └───────────────────────────────────────┘ Attr ---- Function: Replacement for COLOR, especially handy when using bright background colors. Group: Video attributes Syntax: DECLARE SUB Attr (Fore%, Back%) Attr does the same thing as COLOR: setting the colors for the text and its background. However, the blink bit is not being set by increasing the number of the text (foreground) color with 16, but by increasing the number of the background color with 8. This way of stating the color numbers is more convenient when applying bright background colors. In that case you can use the same set of color numbers for the foreground as well as for the background color. When once you established a color combination by a call to Attr, calling GetAttr informs you which color combination that is. The input parameters are: Fore% : the number of the text or foreground color Back% : the number of the background color If you want to change only one of both colors, you must give the other the value -1 (you can not simply skip it, as with COLOR). If you give Back% a value of 8 or higher the background takes the color with the number given by Back less 8 and the text is going to blink. However, if you did set the blink bit, that is the highest bit of the background color number, to obtain bright background colors you simply get a bright background color. To set the blinkbit you can use the ToggleBlinkBit routine, also included in this library. BlinkStatus% ------------ Function: Looks if blinking text is enabled or disabled Group: Video attributes Syntax: DECLARE FUNCTION BlinkStatus% () Requires: Loading of QBASIX.EXE This function returns -1 if setting the blink bit results in a blinking text, and it returns 0 if it brightens the background. When using this function it is convenient to define the constants BRIGHT = 0 and BLINKING = -1. Obvious comparisons as IF BlinkStatus = BRIGHT THEN are possible then. For more information read the comment with routine ToggleBlinkbit. Cmd$ ---- Function: Passes a command line, set by means of the switch /cmd (as with QB) when calling QBASIC, to the program. Group: Command line Syntax: DECLARE FUNCTION Cmd$ () If QBASIX is loaded you can start QBASIC with command line parameters for the program to execute. The way you do that is the same as with QuickBasic, the big brother of QBASIC, by concluding the starting command with the parameter /cmd, followed by the command line parameters you wish to provide. An example: QBASIC /RUN program /CMD parameters for the program Nota bene: this does not work if QBASIX is not loaded. In that case QBASIC considers /cmd and everything behind it a mistake and stops with a summary of the syntax of the QBASIC command. With the Cmd$ function you can find out which parameters are given at the command line, just as with COMMAND$ in QuickBasic. In contrast to what COMMAND$ does Cmd$ preserves the case of letters. A command line may not be longer than 80 characters. When you provide a command line longer than that it will be truncated down to a length of 80. Exch% ----- Function: Exchanges high and low byte of integer Group: Processing integers Syntax: DECLARE FUNCTION Exch% (SomeInt%) SomeInt% is the integer variable, the high and low bytes of which have to be exchanged. The result is the value of the function. Example: suppose that the integer is &H5A21 (23073 decimal), then the result is &H215A (8538 decimal). FillWindow ---------- Function: Colors foreground and/or background of a rectangular text screen area and/or fills it with a character Group: Screen Syntax: DECLARE SUB FillWindow (Top%, Left%, Bottom%, Right%, _ Ascii%, Fore%, Back%) Requires: Loading of QBASIX.EXE The meaning of the variables is as follows: - Top% and Left% are the coordinates of the top left corner of the screen window to fill. - Bottom% and Right% are the coordinates of the bottom right corner of the screen window to fill. - Ascii% is the ASCII code of the character to place, - Fore% is the color code of the desired text color, - Back% is the color code of the desired background color The routine does not check the validity of the given coordinates. They must be at least 1 and at most the number of screen rows or columns of the active video mode. Moreover the coordinates of the bottom right corner must be greater than or equal to the corresponding coordinate of the top left corner. The existing state as to an attribute - character, text color or background color - does not change if instead of a (positive) attribute code a negative number is given. Suppose that only the text color of the window (5, 10, 15, 40) must be changed in red (code 4), then FillWindow must be called as: CALL FillWindow (5, 10, 15, 40, -1, 4, -1) GetActiveColor -------------- Function: Returns the screen color active in DOS Group: Video information Syntax: DECLARE SUB GetActiveColor% Requires: Loading of QBASIX.EXE GetActiveColor returns the screen color active in DOS, as can be set by means of ANSI commands. The function does not require parameters. The lowest four bits of the returned value constitute the code of the text color. It can be in the range from 0 through 15. The next three bits represent the background color. Normally this code can take the values 0 through 7. The highest bit is the blink bit. Its meaning depends on a setting in the BIOS. Normally the blinkbit lets the text blink. However, its meaning can be set so that it makes the background bright. To reset the meaning of the blinkbit you can use the ToggleBlinkBit routine, also included in this library. Which meaning is operative at a certain moment can be examined with the BlinkStatus% function. You get the separate colors in the following way ColorCode% = GetActiveColor% TextColor% = (ColorCode% AND 15) Background% = ColorCode% \ 16 In this form you can use them with QBASIX' routine Attr. If you want to use them with COLOR, you have to calculate them as follows: ColorCode% = GetActiveColor% TextColor% = (ColorCode% AND 15) + 16 * (ColorCode% \ 128) Background% = ((ColorCode% \ 16) AND 7) GetAttr ------- Function: Returns the colors set with the previous call of Attr Group: Video attributes Syntax: DECLARE SUB GetAttr (Fore%, Back%) GetAttr returns the numbers of the colors you previously set with Attr. The output parameters are: Fore% : the number of the text or foreground color Back% : the number of the background color For more information continue reading with the description of Attr. GetCursorLoc ------------ Function: Gets the cursor location by way of the BIOS Group: Video attributes Syntax: DECLARE SUB GetCursorLoc (Row%, Column%) Requires: Loading of QBASIX.EXE and SetCursorLoc ------------ Function: Sets the cursor location by way of the BIOS Group: Video attributes Syntax: DECLARE SUB SetCursorLoc (Row%, Column%) Requires: Loading of QBASIX.EXE The parameters Row% and Column% are the row and column coordinate of the cursor position, respectively. Both only work for page 0, the default page. The top left corner of the screen is (1,1), just as in BASIC. BASIC commands sending output to the screen do not react to the SetCursorLoc command. Therefore use LOCATE instead. GetCursorLoc gives the same result as BASICs CSRLIN and POS. The two routines are useful if you send your output to the screen by way of DOS. The way you do that is by opening the screen as a DOS device with the name "CONS:", as recognized by BASIC, or with the name "CON", which is recognized by DOS. It goes as follows: OPEN "CONS:" FOR OUTPUT AS #1 ... PRINT #1, ... ... CLOSE #1 Output to the screen obeys the LOCATE command, it is true, but BASIC does not keep the position of the cursor. As a result CSRLIN and POS do not return the correct value. Instead of them GetCursorLoc has to be used. Now you will wonder why not always use the ordinary PRINT statement to send output to the screen. After all that is faster. Well, suppose you want to redirect the output to a file in order to view it at your ease later on. That is possible, but only if DOS acts as an intermediary. PRINT does not use DOS, however! An other advantage of output by way of DOS can be that DOS colors will be used automatically. GetVideoInfo ------------ Function: Returns information about the video configuration Group: Video information Syntax: DECLARE SUB GetVideoInfo (Video AS VideoType) Requires: Loading of QBASIX.EXE GetVideoInfo places information about the video configuration in a record of the type VideoType. This type has the following structure: TYPE VideoType Mode AS INTEGER : videomode Rows AS INTEGER : text: number of screen rows Cols AS INTEGER : text: number of screen columns Page AS INTEGER : text: number of active screen page Offs AS INTEGER : text: offset of active page in video memory Segment AS INTEGER : text: segment of the same CRT AS INTEGER : adapter: MDA = 1, CGA = 2, EGA = 3, MCGA = 4, VGA = 5, HERC = 11, OTHER = 0 Colour AS INTEGER : -1 (TRUE) if color screen, 0 (FALSE) if monochrome screen Port AS INTEGER : port of video controller END TYPE The video mode is the mode as reported by the BIOS. This number is not the same as the screen number according to BASIC!. Consult an appropriate book for the codes given by the BIOS, for instance "Programmers quick reference guide IBM ROM BIOS", by Ray Duncan, published by Microsoft Press. With IBM video adapters the text modes are: 0 through 3 (color) and 7 (monochrome). The other modes are graphic modes. The modi numbered 20 and higher are not standard. For the sake of security their memory segment is given as &HA000. Often that is the correct value, but &HB000 and especially &HB800 do appear also. Consult the manual of your video adapter for that. For the sake of a better recognizibility of the adapter code the following constants are defined as a supplement to VideoType: CONST OTHER = 0, MDA = 1, CGA = 2, EGA = 3, MCGA = 4, VGA = 5 GetVideoMode% ------------- Function: Returns the active video mode Group: Video information Syntax: DECLARE FUNCTION GetVideoMode% () Requires: Loading of QBASIX.EXE The goal of this function is to be able to examine quickly which video mode is active. The ballast of a complete Videotype variable is avoided. Getvideomode therefore is much faster than GetVideoInfo. Hi% --- Function: Returns high byte of integer Group: Processing integers Syntax: DECLARE FUNCTION Hi% (SomeInt%) SomeInt% is the integer variable, the high byte of which is requested. The result is the value of the function. Example: suppose that the integer is &H5A21 (23073 decimal), then the result is &H5A (90 decimal). InterruptX ---------- Function: Executes interrupt Group: System Syntax: DECLARE SUB InterruptX (Number%, InReg AS RegTypeX, _ OutReg AS RegTypeX) Requires: Loading of QBASIX.EXE By means of this routine software interrupts can be executed in a BASIC program. It replaces the routine of the same name supplied by Microsoft. Its functionality is the same. The number of the interrupt service routine to execute has to be be specified as the first parameter of InterruptX. The input values of the registers should be placed in InReg, the output values go in OutReg. Both variables are of the type RegtypeX. The interrupt number can not be lees than 0 or greater than 255. If a number is given outside these limits, the number will be set to -1 (0FFFFh) to indicate an error. This is taken from the original QuickBasic routine. By means of InterruptX the registers AX, BX, CX, DX, BP, SI, DI, DS and ES can be set and, after calling the ISR, be read. If one does not want to change the registers DS, ES and/or BP, they should be provided to the routine with the value -1 (0FFFFh). In that case the routine will return with the actual value of these registers immediately after executing the interrupt. In case a DOS interrupt &H21 is being executed with this routine register BP is not used, notwithstanding the value of Inreg.BP. If a critical error appears when using this routine for DOS functions the critical error handler of BASIC comes in action. As a consequence the program, when returned from the interrupt routine, will come under control of an error handling routine activated by ON ERROR GOTO, or will stop with an error message if such an error handler is not available. A not critical error, such as for instance file not found, does not trigger a BASIC error and therefore has to be catched in another way. If an error has occurred the first bit - that is the carry bit - of the flags register is on (that is equal to 1). In that case the error handling routine can be activated. Now however it must not react to BASIC error numbers, but to DOS error numbers. IntMax% ------- Function: Returns the maximum of 2 integers Group: Processing integers Syntax: DECLARE FUNCTION IntMax% (Int1%, Int2%) Int1% and Int2% are the integers the maximum of which has to be determined. The result is the value of the function. IntMin% ------- Function: Returns the minimum of 2 integers Group: Processing integers Syntax: DECLARE FUNCTION IntMin% (Int1%, Int2%) Int1% and Int2% are the integers the minimum of which has to be determined. The result is the value of the function. Lo% --- Function: Returns low byte of integer Group: Processing integers Syntax: DECLARE FUNCTION Lo% (SomeInt%) SomeInt% is the integer variable, the low byte of which is requested. The result is the value of the function. Example: suppose that the integer is &H5A21 (23073 decimal), then the result is &H21 (33 decimal). LptReady% --------- Function: Determines if printer is ready and passes printer status Group: Printer Syntax: DECLARE FUNCTION LptReady% (Lpt%, Status%) Requires: Loading of QBASIX.EXE LptReady% returns -1 (TRUE) if the printer is ready and 0 (FALSE) otherwise. Input parameters: Lpt% : number of the printer to be examined (1, 2 or 3). Output parameter: Status% : extended specification of the printer status. In the Status% variable the printer status according to the BIOS is characterized by the sum of one or more of the following values: 1 - the printer does not react within a fixed time; 8 - I/O error; 16 - the printer is selected; 32 - the printer is out of paper; 64 - printer acknowledgement; 128 - printer not busy; 256 - printer not connected; 512 - invalid printer number. The values 256 and 512 are values attributed not by the BIOS but by the function itself. The printer is ready if it is selected and not one of the errors 1, 8 or 32 has occurred. You can test for each of the conditions by means of the operator AND, for instance: IF Status% AND 32 THEN PRINT "The printer is out of paper" END IF MemCopy ------- Function: Copies a number of bytes from one memory location to another Group: Memory Syntax: DECLARE SUB MemCopy (Bytes&, SourceSeg%, _ SourceOffs%, TargetSeg%, TargetOffs%) Requires: Loading of QBASIX.EXE This routine copies a number of bytes from one memory location to another. The input parameters are, first, the number of bytes to copy: Bytes& : the number of bytes to copy, and next the segmented addresses of source and target: SourceSeg% : the segment of the source address, SourceOffs% : the offset of the source address, TargetSeg% : the segment of the target address, TargetOffs% : the offset of the target address. The maximum number of bytes to copy in one go is 64 Kb. You can copy bytes from every part of memory to every other part. The target may partially overlap the original location. Be cautious in using this routine. It is easy to overwrite information essential for the operation of the program, or even the PC. The least bad thing possible to happen then is that the PC stops functioning, after which you have to start it anew. However, in special cases it can occur that for instance information on the hard disc is overwritten. Copying from one BASIC variable to another is easy and comparatively dangerless. For that you have to use the pointer functions VARSEG and VARPTR, unless it concerns variable length strings. In that case you have to use the pointer function SADD (that is StringADDress). Note the number of bytes to copy: if the number of bytes is greater than fits in the target variable information following that variable is overwritten. That can have nasty consequences. Maybe the question will now arise: why use MemCopy for copying of variables? Can't one simply use the BASIC assignment command for that, for instance A = B? Well, that will do for simple variables, but not for arrays. For in that case a loop over all elements should have to be made. With MemCopy you can do it in one single command. Note that this can't be done with string arrays. If you apply MemCopy to string arrays you make a mess of your computer's memory and without doubt your PC will throw it up. An other possible application of MemCopy is copying of information to and from the video memory. MemScan& -------- Function: Scans a memory block of at most 64Kb for a string Group: Memory Syntax: DECLARE FUNCTION MemScan& (Bytes&, SourceSeg%, _ SourceOffs%, Search$) Requires: Loading of QBASIX.EXE This function scans an arbitrary memory block, beginning at a specified address and having a certain length, for the first ocurrence of a string, that is the search string. The maximum length of the memory block to scan is 64 Kb (65535 bytes). If the string is found the function returns its offset relative to the specified segment. Otherwise the function returns -1. The input parameters are, first, the number of bytes to scan: Bytes& : the number of bytes to scan. and next the segmented address of the start of the memory block to scan: SourceSeg% : the segment of the address of the memory block to scan, SourceOffs% : the offset of the same. You can use MemScan to scan the contents of a variable for a certain string. In that case you have to use BASIC's pointer functions to provide the variable's address: VARSEG for the segment, SADD for the offset of variable length strings, and VARPTR for the offset of all other variables. As the number of bytes to scan you pass the length of the variable. MemScan lends itself very well for scanning fixed length strings. Using MemScan instead of the BASIC function INSTR has the advantage that no temporary variable length string is made and erased afterwards. That makes a difference in space and time. For scanning a string of variable length you can as well use INSTR. MSDOS ----- Function: Executes DOS interrupt Group: System Syntax: DECLARE SUB MSDOS (InReg AS RegTypeX, _ OutReg AS RegTypeX) Requires: Loading of QBASIX.EXE MSDOS is a general interface for the functions DOS provides by way of its interrupt service routine &H21. It is no more than a shortened call of the standard INTERRUPTX routine. Errors can be trapped with BASIC's ON ERROR only if they are critical, that is to say, errors originating in a device, for instance a drive or a printer. Others errors can be detected only by consulting the flags register. Input parameter: InReg AS RegTypeX: the register values to provide, Output parameter: OutReg AS RegTypeX: the register values returned. The BP register is defined in RegTypeX to be sure, but cannot be used by routine MSDOS. See for further reading the discussion under INTERRUPTX. PeekString$ ----------- Function: Reads a string of specified length from specified address Group: Memory Syntax: DECLARE FUNCTION PeekString$(Segment%, Offset%, Length%) The function returns the string of length Length% beginning at the segmented address passed as a parameter. Segment% : segment of the string address Offset% : offset of the string address Length% : the length of the string PeekWord% --------- Function: Reads a word from the specified address Group: Memory Syntax: DECLARE FUNCTION PeekWord% (Segment%, Offset%) The function returns the integer value of the word (two bytes that are) at the segmented memory address passed as a parameter. Segment% : segment of the word address Offset% : offset of the word address PeekWord does about the same as PEEK, but returns a word (whole integer) instead of a byte (half an integer). Moreover the segment can be passed as a parameter without the need to declare it with DEF SEG. The function is borrowed from a book of Ziff-Davis Press (1991). PokeWord -------- Function: Writes a word to the specified address Group: Memory Syntax: DECLARE SUB PokeWord (Segment%, Offset%, Value%) This routine places the integer value (two bytes) given as Value% at the memory address passed as the first parameter. Segment% : segment of the address Offset% : offset of the address Value% : the value to place in memory PokeWord does about the same as POKE, but places a word (whole integer) instead of a byte (half an integer) at the indicated memory location. Moreover the segment can be passed as a parameter without the need to declare it with DEF SEG. The procedure is borrowed from a book of Ziff-Davis Press (1991). RestoreScreen ------------- Function: Restores rectangular text screen area (window) from buffer array Group: Screen Syntax: DECLARE SUB RestoreScreen (ScreenBuffer%()) Requires: Loading of QBASIX.EXE and SavePartScreen -------------- Function: Saves screen window with cursor location and color setting in buffer array Group: Screen Syntax: DECLARE SUB SavePartScreen (Top%, Left%, Bottom%, _ Right%, ScreenBuffer%()) Requires: Loading of QBASIX.EXE and SaveScreen ---------- Function: Saves full screen with cursor location and color setting in buffer array, taking into account the active video mode Group: Screen Syntax: DECLARE SUB SaveScreen (ScreenBuffer%()) Requires: Loading of QBASIX.EXE SaveScreen lets you store the screen contents in a buffer in order to be able to restore the screen to its old state later on. Prior to calling SaveScreen you have to declare a dynamic array ScreenBuffer, in which the routine can store the screen contents. You don't need to give the right number of elements yourself. If the number of elements is too small SaveScreen takes care of making the buffer large enough. So you can confine yourself to, for instance: REDIM ScreenBuffer%(0) Note that the command REDIM is used in stead of DIM. Using REDIM will make the array dynamic, so its size can be changed later on. There are other ways for making an array dynamic, but this is the easiest. SaveScreen supports any number of rows or columns, but only one screen page. By default this is screen page number 0. Using SaveScreen is of course somewhat wasteful in its claim on memory if only a part of the screen really has to be saved. The routine SavePartScreen is introduced to do something about that. With this routine it is possible to store a part of the screen - a window - in a buffer. SavePartScreen too will take care of making the buffer large enough. (Top%, Left%) are the co-ordinates of the top left corner of the window, and (Bottom%, Right%) those of the bottom right corner. Top% and Bottom% relate to the row co-ordinate (y), where as Left% and Right% refer to the column co-ordinate (x). It may be clear that now you have to check yourself if the co-ordinates fit the size of the screen. The window contents are restored with the same routine as with which a complete screen is restored, that is, with RestoreScreen. You can save more windows at the same time by defining more screen buffers and save every window in its own buffer. SetCmd ------ Function: Changes the command line meant for the basic program from inside QBASIC Group: Command line Syntax: DECLARE SUB SetCmd (CmdStr$) If QBASIX is loaded you can start QBASIC with a command line for your program to run, preceded by the switch /cmd. By calling the function Cmd$ in the program you can find out which command line is given, just as you can do in QuickBasic by calling COMMAND$. If you are testing your program it can be convenient to be able to change the command line from inside QBASIC. That is the purpose of the SetCmd procedure. When you insert it in your program you can use it from the immediate window. Press F6 to go to that window and enter there setcmd "the new command line" followed by Enter. The text between quotes is to be replaced by the command line you wish to provide. The lengthe of the command line may not exceed 80 characters. When you enter a line longer than that it will be truncated to the maximum length. When your program runs well one day, SetCmd has done its service and you can delete it from the program. SetCursorLoc ------------ Function: Sets the cursor location by way of the BIOS Group: Video attributes Syntax: DECLARE SUB SetCursorLoc (Row%, Column%) Requires: Loading of QBASIX.EXE See for description under GetCursorLoc. SetError -------- Function: Sets termination code (error level) of program Group: Termination code Syntax: DECLARE SUB SetError (ErrorLevel%) Requires: Loading of QBASIX.EXE With SetError the termination code or error level of the running (basic) program can be set. Input parameter: ErrorLevel% : the termination code to set (0 - 255). If the program is started in a batch file, its error level at termination can be obtained afterwards by means of IF ERRORLEVEL. Depending on its value the execution of the batch file can then be continued in a proper way. Nota bene: if you set a termination code once it remains in force as long as you stay inside QBASIC. It makes no difference if you terminate the program and subsequently run another program, as long as you don't leave QBASIC. SetHi ----- Function: Gives high byte of integer another value Group: Processing integers Syntax: DECLARE SUB SetHi (SomeInt%, HiByte%) SomeInt% is the integer variable to the high byte of which the value of HiByte% must be attached. The existing value of SometInt% is overwritten. Example: suppose that SomeInt% has the value &H5A21 (23073 decimal), and that we choose &HD4 (212 decimal) as the value of HiByte%, then SomeInt% will get the new value &HD421 (54305 decimal). SetLo ----- Function: Gives low byte of integer another value Group: Processing integers Syntax: DECLARE SUB SetLo (SomeInt%, LoByte%) SomeInt% is the integer variable to the low byte of which the value of LoByte% must be attached. The existing value of SometInt% is overwritten. Example: suppose that SomeInt% has the value &H5A21 (23073 decimal), and that we choose &H8E (142 decimal) as the value of LoByte%, then SomeInt% will get the new value &H5A8E (23182 decimal). SetWord% -------- Function: Forms integer from high byte and low byte Group: Processing integers Syntax: DECLARE FUNCTION SetWord% (HiByte%, LoByte%) HiByte% and LoByte% contain the values of the high byte and the low byte respectively of the integer value to form. The resulting value is attached to the function SetWord%. Example: suppose we choose &H77 (119 decimal) as the high byte's value, and &H0C (12 decimal) as the low byte's value, then the result is &H770C (30476 decimaal). Shift ----- Function: Shifts bits of integer a number of places to the left or the right Group: Processing integers Syntax: DECLARE SUB Shift (Direction%, SomeInt%, Bits%) Requires: Loading of QBASIX.EXE With this procedure you can shift the bits of an integer a number of places to the left or to the right. Input parameters: Direction% : indicates the direction in which to shift: 0 for left, and 1 for right. SomeInt% : integer the bits of which are to be shifted. Bits% : number of positions to shift. When shifting to left the highest Bits% bits will be lost, when shifting to right the same will be the case for the lowest Bits% bits. When shifting to left the result is equal to SomeInt% * 2 ^ Bits%, and when shifting to right it is equal to SomeInt% \ 2 ^ Bits%. This procedure is much faster however. It is convenient to define the constants LEFT = 0 and RIGHT = 1 when using this procedure. Clear commands as Shift LEFT, number%, 2 are possible then. ToggleBlinkBit -------------- Function: Enables or disables blinking text Group: Video attributes Syntax: DECLARE SUB ToggleBlinkBit (Toggle%) Requires: Loading of QBASIX.EXE The highest bit of the color byte of a screen position - the color attribute - can have two different meanings: 1. The text blinks. 2. The background is bright. It derives its name "blink bit" from the first meaning. By default the first meaning is operative. With the help of the ToggleBlinkBit procedure it is possible to choose which meaning the blink bit will have. If an odd value is chosen for the parameter Toggle% the blink bit will let the text blink, otherwise it will make the background bright. In that last case you have the choice of eight extra, bright colors for the background, but blinking text is not possible anymore. The blink bit's meaning you choose is effective for the whole screen immediately, not only from the current position on the screen. The blink bit is defined for text modes only. The routine also works for the older MDA and CGA screens. It is convenient to define the constants BRIGHT = 0 and BLINKING = -1 when using this function. Clear commands as ToggleBlinkBit BRIGHT are possible then.