Turbo Basic

• To move to the root directory: The root directory is the original directory. It isthe parent (or grandparent) of all directories (and subdirectories). When you arein the root directory, you see this prompt: C: \ > .To move to the root directory from any other directory, simply typeCHOIR \ EnterThe backslash without a directory name signals DOS that you want to returnto the root directory.Setting Up an Operating EnvironmentIf you have some special hardware needs or if you're a developer in need of adynamic environment, being able to set environment variables will afford you somechoices. Environment variables actually override compiler and/or program options,and are determined by using the SET command in DOS.Environment variables have an effect on the entire environment in which aprogram is executed. Thus after setting a variable, it's in effect until you reset it toanother value or turn off your machine. If you find yourself setting these valuesconsistently one way, you may want to enter the SET command into a batch file oryour AUTOEXEC.BAT file (see the earlier section detailing this file).Turbo Basic's environment variables allow you to override compiler and runtimeoptions for 8087 support and Color/Graphics Adapter (CGA) "snow" checking.For example, in the follOwing example you're setting up your environment for 8087use by typing at the DOS promptSET 87=yeswhere yes means you have an 8087; no means even if you have an 8087 don't use it.The default setting is yes.In the case of CGA snow-checking, you could typeSET CGASNOWCHK=nowhere no doesn't do snow-checking and yes does snow-checking. The default settingis yes.When your compiler begins executing or when a generated .EXE file startsexecuting, they actually search the environment variable space for these variables.Though it's not necessary to set these variables, they're available when you needthem. If you choose not to set them, the current directory searches for files andcreates temporary ones to store the default variables.A DOS Primer 439