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Q60133: Description of How LOCATE Can Change the Cursor Size

Article: Q60133
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S890714-76 B_BasicCom | mspl13_basic
Last Modified: 3-APR-1990

The LOCATE statement provides the ability to change the cursor size in
text mode (SCREEN 0). The number of scan lines varies depending on the
video system and the operating system.

This information applies to Microsoft QuickBASIC Versions 4.00, 4.00b
and 4.50 for MS-DOS, Microsoft BASIC Compiler Versions 6.00 and 6.00b
for MS-DOS and OS/2, and Microsoft BASIC Professional Development
System (PDS) Version 7.00 for MS-DOS and OS/2.

The following table shows the valid settings for most video systems:

   Video System | Op Sys | Scan lines
   -------------+--------+-----------
   Hercules     |  DOS   |    12
   CGA/EGA/VGA  |  DOS   |     8
   Any          |  OS/2  |    16

The cursor is a text mode feature and is not available for use with
the LOCATE statement in graphics modes. INPUT is the only statement
that automatically uses a cursor in graphics modes.

The following information, taken from the QBX.EXE online help from
BASIC PDS 7.00, is the description of the usage of the start and stop
lines in the LOCATE statement:

The start and stop lines are the CRT scan lines that specify the
following:

1. Which pixels on the screen are lit.

   A wider range between the start and stop lines produces a taller
   cursor, such as one that occupies an entire character block.

   In OS/2 real mode and under DOS, LOCATE assumes there are eight
   lines (numbered 0 to 7) in the cursor. In OS/2 protected mode, there
   are 16 lines (numbered 0 to 15).

2. When start% is greater than stop%, LOCATE produces a two-part
   cursor.

   If the start line is given, but the stop line is omitted, stop%
   assumes the same value as start%.

   A value of 8 for both start% and stop% produces the underline
   cursor.

   The maximum cursor size is determined by the character block size
   of the screen mode in use.

   Setting start% greater than stop% displays a full-height cursor on
   VGA-equipped systems.

Code Example
------------

The following code example prompts you for start and stop scan lines
and displays the cursor:

SCREEN 0
CLS
LOCATE 8, 10

DO
  INPUT "Start line: ",StartLine%
  IF StartLine% = -1 THEN END       'Enter -1 to end
  LOCATE 9, 10
  INPUT "Stop  line: ",StopLine%
  CLS
  LOCATE 10, 10, 1, StartLine%, StopLine%
LOOP

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