A brief retrospective on SPARC register windows

As I work on moss and research modern processor design patterns and techniques, I am also looking for patterns and techniques from the past that, for one reason or another, have not persisted into our modern machines. While on a run this week, I was listening to an old Oxide and Friends episode where Bryan, Adam, and crew were reminiscing on the SPARC instruction set architecture (ISA). SPARC is a reduced instruction set computer (RISC) architecture originally developed by Sun Microsystems, with the first machine, the SPARCstation1 (a.k.a. Sun 4/60, a.k.a Campus), being delivered in 1987. It was heavily influenced by the early RISC designs from David Patterson and team at Berkeley in the 1970s and 1980s, which is the same lineage from which RISC-V has evolved. Given the decision to base moss on the RISC-V RV64I ISA, I was interested to learn more about the history and finer details of SPARC.

Daniel Mangum

The sad thing is that SPARC is pretty close to dead at this point, with the two major players in the high-end - Oracle and Fujitsu - throwing in the towel half a decade ago. There's some lower-end work, such as the LEON chips, but those efforts, too, seem to be going nowhere at the moment. Definitely sad, since I've always been oddly obsessed with the architecture, and hope to still somehow get my hands on the last UltraSPARC workstation ever built (the Sun Ultra 45, which is, sadly, incredibly expensive on the used market). There's also a whole boatload of servers on the used market with fancier, newer SPARC processors, but as far as I know, none of those support any form of even barely usable graphics, making them useless for weird people like me who want to run a desktop on them.