This was William Gibson's first published story (1977). It can now be found in the anthology Burning Chrome.
Despite being the first, it has the distinct Gibson feel to it, both in narrative technique (the story is told through short flashbacks as the protagonist lies awake in bed reminiscing during a 4AM brownout, and follows two parallell threads), and in its aproach to describing the future (very cyberpunkly, the story is about someone being left by his girlfriend, and things like simstim and lack of cars are only mentioned in passing).