According to Wikipedia DJB's last release was 1998. 64-bit Alpha and SPARC V9 were in widespread use by then. Even Linux was ported to Alpha in 1995.[1] See https://www.linuxjournal.com/article/1044
[1] Actually, Jim Paradis announced the Linux/Alpha development kit January 23, 1995 on comp.os.linux.announce (Message-ID: 3g0787$59i@kruuna.Helsinki.FI). So it's possible he had the kernel ported in late 1994. He announced a fully functional distribution July 1, 1995. (Message-ID: 3t34ph$mi@kruuna.helsinki.fi)
[1] Actually, Jim Paradis announced the Linux/Alpha development kit January 23, 1995 on comp.os.linux.announce (Message-ID: 3g0787$59i@kruuna.Helsinki.FI). So it's possible he had the kernel ported in late 1994. He announced a fully functional distribution July 1, 1995. (Message-ID: 3t34ph$mi@kruuna.helsinki.fi)