4 ms·

> Alpha is a great example of an ISA being pretty obsolete outside of owning an old DEC computer Actually, that isn't the case. The Chinese Sunway is based on

> Alpha is a great example of an ISA being pretty obsolete outside of owning an old DEC computer Actually, that isn't the case. The Chinese Sunway is based on the Alpha 21164 [1]. The Sunway TaihuLight is 3rd on the supercomputer list [2]. [1] https://en.wikipedia.org/wiki/Sunway_(processor) https://en.wikipedia.org/wiki/Sunway_(processor) [2] https://www.top500.org/lists/2018/11/ https://www.top500.org/lists/2018/11/ (In fact, the Sunway SW26010 has moved on from the Alpha but is still heavily inspired by it.) As for RISC-V itself, I'd be interested in a comparison article between RISC-V and Cray. I think Seymour Cray came up with most good RISC ideas long before Patterson+Ditzel. Indeed, RISC-V is now basing their vector extension on ... Cray. RISC-V as an open source ISA/implementation is one thing. But as a collection of ideas it is another. What ideas distinguish RISC-V from Cray? My personal take is that RISC-V is RISC without the architectural warts of its predecessor RISCs. No register windowing, no tagged integers, no branch delay slot, .... Less is good. But what does RISC-V add that distinguishes it from Cray?

jessfraz 8y ago
wow I had no idea thanks!
bogomipz 8y ago
It seems like there is quite a gap between the Cray's RISC based hardware which I believe were very successful and the introduction of Sun SPARC hardware. Could you or anyone else comment on the reason for this? Was it simply the arrival of research funding from DARPA at Berkeley/Standford in this area?
- CalChris 8y ago
  Berkeley RISC and Stanford MIPS are circa 1980. I think the enabling factor for them was the availability of fab resources. The RISC-1 had 44,500 transistors. In 1980, Berkeley could get that fabbed for really not much dinero. So it wasn't the funding per se. It was the reduction of fab costs to something they could get funded. Same with the Stanford Geometry Engine. Call it the Carver Mead revolution. The CRAY-1 is 1975. The IBM 801 is 1980 (started in 1975). SPARC comes along in 1987. So I don't think it was the funding. I really think it was the availability of cheap fabs for small tapeouts. The Cray-1 was announced in 1975 and shipped in 1976. IBM took 5 years. It reminds me of the IBM memo all over again: https://www.computerhistory.org/revolution/supercomputers/10/33/62 https://www.computerhistory.org/revolution/supercomputers/10... To which Cray responded, “It seems like Mr. Watson has answered his own question.” Arguably, Berkeley and Stanford's research groups were a lot more like Cray's team.
  - bogomipz 8y ago
    Interesting yeah. I just came across the following items: "why did Sun and most other minicomputer oem's turn to RISC? the relatively low cost accessibility to semiconductor fabrication using gate arrays. Chip manufacturers who needed high volumes to recoup their capital investments of hundreds of millions of dollars (now billions) had figured out a way of producing standard product families of chips called gate arrays, which were identical except for the last few steps of the production process which defined the interconnections. This enabled computer systems companies to buy state of the art fabrication by effectively buying batches of wafers on a time-share basis from a few thousand dollars upwards, instead of the millions of dollars required previously."[1] I'm somewhat unsure or gate arrays themselves would have enabled this though as I think of gate arrays as alternative to a microprocessor. Might you know? Also it seems that SUN had their prototypes built down at USC's Viterbi School FAB: "MOSIS has prototyped more than 50,000 chip designs for businesses, government agencies and universities, including the originals of many now widely used commercial chips, such as those used in Sun Microsystems SPARC and SGI’s MIPS systems."[2] Also it appears that the rise of CAD also helped usher in the era of producing RISC chips for these vendors as well: "the deskilling of the chip design process by sophisticated computer aided design (CAD) tools enabled computer systems designers to design, test and simulate most of the design stages at their workstations, without needing knowledge of the underlying manufacturing process parameters. The software enabled designers to work at a logic function-block level without having to worry too much about the realities of interconnections, datapaths and process variations. This revolution in hardware logic design was akin to the invention of high level programming languages which enabled programmers to write their applications in terms of the problem, rather than needing to know exactly how the computer was built or wired together."[1] [1] http://www.sparcproductdirectory.com/history.html http://www.sparcproductdirectory.com/history.html [2] https://viterbi.usc.edu/news/news/2005/2005_05_23_mosisstudent.htm https://viterbi.usc.edu/news/news/2005/2005_05_23_mosisstude...
    - CalChris 8y ago
      I really don't know much but I do remember people who were deskilled out of hand chip layout. It's like component or analog skills. Yes, those are skills but then suddenly no one needs them. Initially hand layout could say but we're better and that was true. But then tools got better and designs got a LOT bigger. I think you can add this to the affordability argument. It was affordable for a research team to do a RISC where previously only big companies could do that.
deepnotderp 8y ago
Better marketing? Being "open source"?

jessfraz 8y ago

wow I had no idea thanks!

bogomipz 8y ago

It seems like there is quite a gap between the Cray's RISC based hardware which I believe were very successful and the introduction of Sun SPARC hardware. Could you or anyone else comment on the reason for this? Was it simply the arrival of research funding from DARPA at Berkeley/Standford in this area?

CalChris 8y ago
Berkeley RISC and Stanford MIPS are circa 1980. I think the enabling factor for them was the availability of fab resources. The RISC-1 had 44,500 transistors. In 1980, Berkeley could get that fabbed for really not much dinero. So it wasn't the funding per se. It was the reduction of fab costs to something they could get funded. Same with the Stanford Geometry Engine. Call it the Carver Mead revolution. The CRAY-1 is 1975. The IBM 801 is 1980 (started in 1975). SPARC comes along in 1987. So I don't think it was the funding. I really think it was the availability of cheap fabs for small tapeouts. The Cray-1 was announced in 1975 and shipped in 1976. IBM took 5 years. It reminds me of the IBM memo all over again: https://www.computerhistory.org/revolution/supercomputers/10/33/62 https://www.computerhistory.org/revolution/supercomputers/10... To which Cray responded, “It seems like Mr. Watson has answered his own question.” Arguably, Berkeley and Stanford's research groups were a lot more like Cray's team.
- bogomipz 8y ago
  Interesting yeah. I just came across the following items: "why did Sun and most other minicomputer oem's turn to RISC? the relatively low cost accessibility to semiconductor fabrication using gate arrays. Chip manufacturers who needed high volumes to recoup their capital investments of hundreds of millions of dollars (now billions) had figured out a way of producing standard product families of chips called gate arrays, which were identical except for the last few steps of the production process which defined the interconnections. This enabled computer systems companies to buy state of the art fabrication by effectively buying batches of wafers on a time-share basis from a few thousand dollars upwards, instead of the millions of dollars required previously."[1] I'm somewhat unsure or gate arrays themselves would have enabled this though as I think of gate arrays as alternative to a microprocessor. Might you know? Also it seems that SUN had their prototypes built down at USC's Viterbi School FAB: "MOSIS has prototyped more than 50,000 chip designs for businesses, government agencies and universities, including the originals of many now widely used commercial chips, such as those used in Sun Microsystems SPARC and SGI’s MIPS systems."[2] Also it appears that the rise of CAD also helped usher in the era of producing RISC chips for these vendors as well: "the deskilling of the chip design process by sophisticated computer aided design (CAD) tools enabled computer systems designers to design, test and simulate most of the design stages at their workstations, without needing knowledge of the underlying manufacturing process parameters. The software enabled designers to work at a logic function-block level without having to worry too much about the realities of interconnections, datapaths and process variations. This revolution in hardware logic design was akin to the invention of high level programming languages which enabled programmers to write their applications in terms of the problem, rather than needing to know exactly how the computer was built or wired together."[1] [1] http://www.sparcproductdirectory.com/history.html http://www.sparcproductdirectory.com/history.html [2] https://viterbi.usc.edu/news/news/2005/2005_05_23_mosisstudent.htm https://viterbi.usc.edu/news/news/2005/2005_05_23_mosisstude...
  - CalChris 8y ago
    I really don't know much but I do remember people who were deskilled out of hand chip layout. It's like component or analog skills. Yes, those are skills but then suddenly no one needs them. Initially hand layout could say but we're better and that was true. But then tools got better and designs got a LOT bigger. I think you can add this to the affordability argument. It was affordable for a research team to do a RISC where previously only big companies could do that.

deepnotderp 8y ago

Better marketing? Being "open source"?