Air conditioning eventually reach the upper atmosphere. Once the refrigerant reaches the stratosphere, UV radiation from the Sun homolytically cleaves the chlorine-carbon bond, yielding a chlorine radical. These chlorine radicals catalyze the breakdown of ozone into diatomic oxygen, depleting the ozone layer that shields the Earth's surface from strong UV radiation. Each chlorine radical remains active as a catalyst until it binds with another radical, forming a stable molecule and quenching the chain reaction. Prior to 1994, most automotive air conditioning systems used R-12 as a refrigerant. It was replaced with R-134a refrigerant, which has no ozone depletion potential. Old R-12 systems
S-BASIC for the commercial Spectral UV-Visible software. Jerry Pournelle in 1983 wrote that SBASIC "is quite nice", stating that it "rivals CB-80". He presumed that Kaypro users would "will begin by using Microsoft MBASIC, then start translating their programs into S-BASIC and learn more about structured programming". Pournelle added, "If I had to give an award for the most unreadable computer document I've ever seen, the original S-BASIC manual would win hands down"; however, Kaypro had rewritten it and "is a great deal more sensible". S-BASIC S-BASIC (for Structured Basic) was a "structured" BASIC variant, distributed with Kaypro CP/M systems. It