True BASIC

Background and Features

When True BASIC appeared on the market in 1985, the BASIC language was widely used on home computers, but with little standardization. Each manufacturer implemented extensions to the language to support features of their hardware. Initially based on Dartmouth BASIC 7 — otherwise known as ANSI BASIC — True BASIC implemented a number of new features over GW-BASIC, and allowed the user a redefinable 16-color, 640×480 pixel backdrop for program editing. True BASIC introduced new functions for graphics primitives like plot, plot area, flood, etc. It also was the first to provide a method for saving a portion of the screen and blitting it elsewhere, but had no proper buffering implementation.

Being a structured programming implementation of the language, it dispensed with the need for line numbers and GOTO statements, although these earlier features can still be used. Use of LET for value assignment became optional. It also allowed for descriptive variable names longer than a single letter plus a single digit. For example, the familiar algebraic equation y = mx + b (y = mx + c for the UK) could be expressed as:

The above code segment would yield "y2= 10".

True BASIC provides statements for matrix arithmetic, a feature that had been present in Dartmouth BASIC since early times, but had been dropped in almost all microcomputer versions of BASIC interpreters due to memory limitations. It also supports global and local variables, which permits recursive functions and subroutines to be written.

There are versions of the True BASIC compiler for DOS, Windows, and classic Mac OS. There is currently no macOS version of True BASIC, although it may be run in a Windows emulator application. PowerPC Macs running Mac OS X can run it through the Classic Environment. At one time, versions for Tandy, Amiga and Atari computers were offered, as well as a UNIX command-line compiler.

The designers wanted to make the language hardware-independent, to allow True BASIC source code to run equally well on any version of their compiler. For the most part they succeed in this endeavor. The drawback for users was that direct access to some features of their machines was not available, but this could be remedied with callable functions and subroutines specially written in assembly language.

Using newer versions of True BASIC, some of the older functions are blocked out. An example of the recent code would be more like this:

RANDOMIZE SET WINDOW 0,20,0,20 SET COLOR 5 !Set the pen and text colour to 5 as true basic has 0-15 colours PRINT "Welcome To ..." !Print "Welcome To ..." on the user's screen. DO !Begin the loop LET x=rnd*20 !Let the value 'x' equal a random number between '0' and '20' LET y=rnd*20 !Let the value 'y' equal a random number between '0' and '20' Pause .1 !Waits 1/10 of a second PLOT TEXT, at x, y: "Fabulous Wikipedia!" !Plot 'Fabulous Wikipedia!' at coordinates 'x' and 'y' LOOP !End the loop END !End the program

As one can see, even without comments (text following the unquoted exclamation point), True BASIC code can be read rather easily. This simple program plots the text "Welcome To ..." at the top left-hand corner of the screen, and then continues into a never-ending loop plotting "Fabulous Wikipedia!" at random coordinates.

An example of simple animation could be like this:

!Draw the Car SET WINDOW 0,20,0,20 SET COLOR 5 BOX AREA 2,6,2,3 BOX AREA 9,13,2,3 BOX AREA 16,20,2,3 SET COLOR 249 PLOT LINES :0,5;20,5 FLOOD 10,1 BOX KEEP 0,20,0,5 IN road$ BOX CIRCLE 2,3,5,6 FLOOD 2.5,5.5 BOX CIRCLE 5,6,5,6 FLOOD 5.5,5.5 SET COLOR 35 PLOT LINES :2.5,6;5.5,6 PLOT LINES :5,6;8,6;8,8;6,8;6,10;2,10;2,8;0,8;0,6;3,6 FLOOD 4,8 SET COLOR 248 BOX AREA 4,5,8,9 BOX KEEP 0,8,5,10 IN car$ !Save the car in 'car$' FOR x=1 TO 20 STEP 1 !Create a 'for' loop BOX SHOW road$ AT 0,0 BOX SHOW car$ AT x,5 PAUSE .1 CLEAR NEXT x !End the 'for' loop END !End the programs

Excessive CPU usage

True BASIC suffers from excessive CPU usage. Several users have complained about their programs and the editor using up 100% of their CPU (or core). This appears to be caused by the editor and user's programs using a loop which constantly polls the keyboard and mouse for events. The problem has been known since at least the end of 2010, yet as of early 2014 is still being worked on.

Reception

Jerry Pournelle in 1985 asked, "why do we need True BASIC at all? [It] doesn't seem to do anything regular BASIC doesn't do, and what it does do isn't attacked in a logical or intuitive manner." He criticized the lack of output when encountering an error, preventing interactive debugging by "inserting print statements as diagnostics". Pournelle concluded, "I think I'll pass up the opportunity to become a born-again True BASIC believer. I'll enjoy my Microsoft and CBASIC heresies."