Tests to see if the ANSI screen driver is installed

     ISANSI() --> lInstalledDriver


     ISANSI() returns .T. when ANSI.SYS or a comparable driver has been
     loaded from CONFIG.SYS.


     ISANSI() determines if ANSI.SYS or another comparable driver has been
     loaded from CONFIG.SYS.  Some full-page displays require the ANSI
     driver.  If the driver is present, the display is fully operational.


     Warning!  You must implement DSETWINDOW(.F.) for ISANSI() to return
     a correct result.


     If ANSI.SYS is present, output through DOS.  This allows a simple
     terminal emulation:

     IF ISANSI()                  // ANSI driver present?
        COM_DOSCON(dDate)         // Output via DOS
        *...                      // Individual ANSI handling



Introduction Video Functions


 Working With Video Functions

     This module discusses video functions that are either directly or
     indirectly concerned with the screen.  Included are all functions that
     deal with such screen adapters as CGA, EGA and Hercules.  Different
     modes on various adapters are supported, such as a 40-column CGA, a 43-
     line EGA, or a 50-line VGA.


     Many of the functions in this chapter depend on setting the DSETWINDOW()
     switch.  This switch determines if the screen output of external
     programs, as well as DOS, are redirected to a window.
     Clipper Tools output functions are also valid as external.  If the
     default setting in DSETWINDOW() is .T. or on, this rerouting is carried
     out.  Some functions will then return inaccurate, or at the very least,
     different results.  Examples of this are ISANSI() or NUMCOL()


     Many of the functions in this module work with color attributes
     designated as parameters.  These arguments are carried out in three
     different ways:

     A numeric value, which corresponds to a combined color attribute
     (e.g., 7).

     A string in the "NN/NN" form, with two specified numeric values (e.g.,

     A string in the "CC/CC" form, with two specified attributes are
     designated in the form Clipper requires (e.g., "W/N").

     With many functions, the attribute returns a combined numeric value.
     Attributes for the foreground and background are tied together this way.

     Color attributes are constructed as follows:

     Bit                8 7 6 5        4 3 2 1
     Attribute          * R G B        + R G B
           _ _ _ _ _ _  /   _ _ _ _ _ _

           Background   /   Foreground

     Each attribute consists of four bits, which represent a value in the
     range of 0 to 15.  Therefore, there are a total of 16*16, or 256,
     different values from 0 to 255.  These numeric values can be changed
     into the "nn/nn" format, that can be used under Clipper with the
     NTOCOLOR function.  However, it is possible to directly influence this
     combined attribute value.  The following examples show this and relate
     back to the chapter on number and bit manipulation:

     NUMOR( nattr, 128)    // Flashing on
     NUMAND(nattr, 127)    // Flashing off
     NUMXOR(nattr, 128)    // Change flashing
     NUMOR(nattr,  8)      // High intensity on
     NUMAND(nattr, 247)    // High intensity off
     NUMXOR(nattr,  8)     // Switch high intensity

 Special Parameter Type

     With many functions, a parameter may be of the <mIcCharacter|nCharacter>
     type (e.g., an individual character).  This can occur in two different

     Numerically, as the ASCII code of the desired character (e.g., 7).

     Alphanumeric as the character (e.g., ":").

     Because of this, you must not use the CHR() function to change special


     Some of the Clipper Tools functions use a standard attribute and
     character to  delete lines or screen areas.  This attribute is described
     as CLEARA; the character as CLEARB.  You can query both CLEARA and
     CLEARB with the corresponding functions.  At the same time, certain
     preset values are in effect for CLEARA and CLEARB.  The attribute "W/N"
     is the standard preset for CLEARA, while CHR(255) is the character used
     for CLEARB.  If you use this character for CLEARB, it fills the
     background with the corresponding color for every deletion on every
     screen adapter.

     Use the following functions to set standard values for CLEARA and


     If you use the SETCLEARx() functions in conjunction with the
     corresponding parameters (<Attribute> or <Character>), the currently
     existing default value is replaced by a parameter.

 Clipper Functions and Commands Which Delete

     If you use the Clipper Extended Drivers, CHR(255) is used instead of
     a space for all Clipper functions and commands that delete the screen
     in one way or another (see CLEARB).  A CHR(255) is helpful on many
     screen adapters, since in contrast to a space, you can assign it a
     color.  Then, the screen will not appear so fuzzy.

     More precisely, the functions and commands concerned always use the
     delete character set by SETCLEARB(), which uses CHR(255) as the default
     setting.  If you want to use a space to clear in Clipper or
     Clipper Tools, insert a SETCLEARB(32) into the program.

     Re-implement a space for clear:

        CLEAR         // The affected Clipper command

 Video Modes

     Occasionally, there is some confusion about video modes.  You will not
     be able to work in EGA mode just because your computer has an EGA
     adapter built into it.  By the same token, you will not get either EGA
     or VGA modes, if you do not work with graphics.

 EGA43 / VGA50 / VGA28, etc.

     In this section, the concern is not to just get a mode "hardwired"' into
     a card, but for Clipper Tools it is to generate corresponding fonts
     and other settings.  For these reasons, the GETMODE() and GETSCRMODE()
     functions generate their own values that are greater than 255.

     For example, changes to the screen mode concerned with line count can be
     combined with a 40-column mode:

     EGA43()          // 43 lines and 40 columns

 Video Functions and Windows

     You cannot implement functions that change the base address for screen
     memory while windows are open.  This includes all mode changes, as well


      Since this section is about DOS-TEXT mode programming, considered as obsolete and details skipped.

Tools – System Information

Introduction System Information
BIOSDATE()   Determines the system BIOS date
BOOTCOLD()   Triggers a cold boot
BOOTWARM()   Triggers a warm start of the system
CPUTYPE()    Determines what type of microprocessor in use
DOSPARAM()   Retrieves the DOS command line as a string
ENVPARAM()   Reads the entire DOS environment table into a string
ERRORACT()   Recommends action for a DOS error that has occurred previously
ERRORBASE()  Source of the most-recent DOS error
ERRORCODE()  Identifies a DOS error that has occurred previously
ERRORORG()   Origin of the most-recent DOS error
EXENAME()    Returns name and directory of the current Clipper program
FILESFREE()  Specifies the number of files you can open
FILESMAX()   Specifies maximum number of files that can be open at one time
GETCOUNTRY() Queries country setting for the operating system
ISANSI()     Tests to see if the ANSI screen driver is installed
ISAT()       Determines if a program is running on an AT
ISMATH()     Determines if a math coprocessor is installed
MEMSIZE()    Determines size of conventional or extended memory
NUMBUFFERS() Determines the BUFFERS= setting
NUMFILES()   Determines maximum number of files you can open simultaneously
OSVER()      Returns the DOS version number
PCTYPE()     Returns the type of computer in use
SSETBREAK()  Sets and checks the DOS BREAK switch
SSETVERIFY() Sets and checks the DOS VERIFY switch