At the moment, the set of available BASIC commands is very basic: CLS, COLOR, DEF, GOTO, IF … THEN, LET, and PRINT. But those are enough to write some simple programs. Numeric support is limited to integer constants, variables, and operators (no floating-point yet). String variables can be created and printed, but no string operations are available yet either.
PRIMES.BAS was the first BASIC program written to run in both BASIC-DOS and MSBASIC. It computes all primes under 1000.
Let’s watch it run on a 4.77Mhz IBM PC with MSBASIC first.
After it prints:
TOTAL PRIMES < 1000: 168
SYSTEM to return to the BASIC-DOS prompt.
PRIMES.BAS to load and run the same program with BASIC-DOS.
Notice how much faster BASIC-DOS execution is. And BASIC-DOS is performing full 32-bit integer operations (MSBASIC integer operations are only 16-bit).