was stored in a 128-value table. At runtime, when a line number lookup was needed, it would first pick the nearest-but-lower value in the table, retrieve the address, and then begin scanning for the line from that point on. The improvement was most notable in larger programs where the scanning time was increasingly expensive, which is why Turbo-Basic could hit a 5-times increase in larger programs. The other major source of poor performance in Atari BASIC was its very slow binary-coded decimal (BCD) floating point code. The library, contained in a separate 2K ROM and considered part of the operating system as opposed to BASIC itself, had been written in a hurry and never optimized. Some of the routines, notably the multiply and exponents functions, were far slower than they could be. Turbo-Basic fixed this by including its own complete floating-point library, which not only fixed many of these issues but also further optimized the code by unrolling small loops. For programs that used math extensively, the new library resulted in dramatic performance improvements, sending the Atari from near the bottom of the Creative Computing Benchmark lists to near the top, beating a number of machines that were much faster in hardware. New features Among the extra features of Turbo-Basic XL, added to Atari BASIC, are the following: enhanced sound and graphics commands more flexible I/O commands, including disk access structured programming constructs simple debugging facilities See also BASIC A+ References External links [http://www.tmeyer.de/atari/index.html Turbo-Basic XL listings] listings from Happy Computer'' magazine 1985 software Atari 8-bit family software Turbo-Basic XL Turbo-Basic XL Turbo-Basic XL Programming languages created in 1985 BASIC programming language family