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Tanenbaum wasn't that far off. 1. In terms of pure Micro-Kernels he was off. It was tried, the benefits didn't outweigh the drawbacks so people moved to Hybrid

Tanenbaum wasn't that far off. 1. In terms of pure Micro-Kernels he was off. It was tried, the benefits didn't outweigh the drawbacks so people moved to Hybrid Micro-Kernels (Windows NT, OS X, iOS et al) so from that perspective he was about 50% right. 2. Given the way ARM is trouncing everybody in the mobile space, unless Intel manages the biggest comeback since Lazarus the future is almost certainly RISC. Whether this feeds back to the desktop space remains to be seen. 3. Unlikely to happen, although the future is most likely Open Source in some form or other. GPL v3 has largely ruled out GNU dominating as vendors that previously shipped GNU components replace the GPL components with other Open Source Licenses because they find the new terms a bit much.

huggyface 15y ago
the future is almost certainly RISC What does RISC even mean anymore? Seriously, I remember the debates during the early 90s (back when MIPS and friends were going to destroy Intel) and the RISC of then is very different from the RISC of today. Then the merit of RISC was that you literally reduced the instruction set to the minimum possible, putting the demand on the compiler to gang them to do even rudimentary work. The idea was that the simpler silicon would be easier to scale up (frequency scaling was a major problem), and the compiler would have more insight into the operations of a product giving such a product a performance advantage. The MIPS of the 90s had about 45 instructions, total, and a corresponding simplicity of implementation. The 8086 had 114, providing higher level, much more complex silicon, and has grown since then. How many instructions does ARMv7a provide (this is actually a hard question to answer)? It has floating point operations, SIMD / NEON, virtualization support, and on and on and on. I do know that while it once feature just 25,000 transistors (ARM2), a modern ARM9 design like the Tegra2 hosts 26 million transistors for just the cores (not the GPU). I realize that I'm stepping into a linguistic landmine, and various contrived "this is the differentiator" definitions will appear, but the original intent of RISC versus CISC was exactly what I described above. Today the meanings are absolutely nothing like that.
- spiralpolitik 15y ago
  While one of the characteristic of a RISC processor was a simpler instruction set its not the only one. There is also uniform instruction length to make instruction decoding logic simpler and quicker and that a single instruction doesn't takes longer than a single clock cycle. But you are correct that the water today is somewhat muddy especially as CISC processors borrowed stuff from the RISC processors and vice versa. I think someone in the late 90s coined the term CRISP (Complex Reduced Instruction Set Processor) to describe these beasts, although I haven't seen the term mentioned in recent years.

huggyface 15y ago

the future is almost certainly RISC What does RISC even mean anymore? Seriously, I remember the debates during the early 90s (back when MIPS and friends were going to destroy Intel) and the RISC of then is very different from the RISC of today. Then the merit of RISC was that you literally reduced the instruction set to the minimum possible, putting the demand on the compiler to gang them to do even rudimentary work. The idea was that the simpler silicon would be easier to scale up (frequency scaling was a major problem), and the compiler would have more insight into the operations of a product giving such a product a performance advantage. The MIPS of the 90s had about 45 instructions, total, and a corresponding simplicity of implementation. The 8086 had 114, providing higher level, much more complex silicon, and has grown since then. How many instructions does ARMv7a provide (this is actually a hard question to answer)? It has floating point operations, SIMD / NEON, virtualization support, and on and on and on. I do know that while it once feature just 25,000 transistors (ARM2), a modern ARM9 design like the Tegra2 hosts 26 million transistors for just the cores (not the GPU). I realize that I'm stepping into a linguistic landmine, and various contrived "this is the differentiator" definitions will appear, but the original intent of RISC versus CISC was exactly what I described above. Today the meanings are absolutely nothing like that.

spiralpolitik 15y ago
While one of the characteristic of a RISC processor was a simpler instruction set its not the only one. There is also uniform instruction length to make instruction decoding logic simpler and quicker and that a single instruction doesn't takes longer than a single clock cycle. But you are correct that the water today is somewhat muddy especially as CISC processors borrowed stuff from the RISC processors and vice versa. I think someone in the late 90s coined the term CRISP (Complex Reduced Instruction Set Processor) to describe these beasts, although I haven't seen the term mentioned in recent years.