Complex sentence: In 1987, with 17,000 users, BIX moved to a Pyramid 9820 running OS/x. When that became too expensive to run, it was ported to a DEC Alpha server.
Split into simpler sentences: In 1987, with 17,000 users, BIX moved to a Pyramid 9820 running OSx. When the Pyramid became too expensive to run, BIX was ported to a DEC Alpha server.