Date: Thu, 19 Apr 2001 23:20:52 -0700 From: "Charles Burns" <burnscharlesn@hotmail.com> To: mwm@mired.org Cc: questions@freebsd.org Subject: Re: the AMD factor in FreeBSD Message-ID: <F180HB3pHoWD47yicBo00003902@hotmail.com>
next in thread | raw e-mail | index | archive | help
>RISC is pretty much vertical microcode. WISC - which didn't make quite >the same splash - is pretty much horizontal microcode. People wanting >to build fast CISC computers have done so by microcoding them for a >long time, usually using vertical microcode. The 370 line was that >way, as well the high end of the PDP-11 line was that way. Uhh. <confused> My impression was that RISC=Reduced Instruction Set (chip/computer) meant make the chip simpler (but harder to program at the asm level) and execute more, simpler instructions. CISC=have complex instructions and lots of them thus having a higher IPC but many theoretically unneeded transistors. Microcode=Simple software internal to chips or imbedded into battery-backed ROM or FlashROM used to do things like fix simple processor bugs that software can fix. What is vertical and horizontal microcoding? If I am wrong I certainly want to know--and I am curious as to what you are talking about as I have never even heard these terms before. >Cray didn't have to implement a CISC instruction set, so the Cray I >instruction set is very RISC-like, with the exception of the >instructions for dealing with the array processor hanging off the >back. Was RISC vs CISC (terms which didn't even exist in the 70's then the Cray1 was being built) even an issue then? Vector processors have such different priorities than the processors that every other computer uses. What do you mean by "hanging off the back"? You should be a speaker at Defcon--They love to absorb esoteric and almost unknown computer knowledge. (scratches head) Umm. Where can I get more info about this? >The truly cool machines had a writable control store. Huh? >The PDP-11 kit >sold by Heathkit included that as an option. BBN had the ultimate Unix >version, though - they included a C compiler and WCS linker so you >could write new instructions in C, so your function calls turned into >single instructions. What does all this have to do with the price of tea in China? It's all very interesting, but it seems like a collection of random unrelated computer tidbits. I may just not see the point as this is mostly new to me other than the PDP11 (which is still used today) and the Cray, sortof. >My favorite microcode oddity is the IBM PC card IBM sold that used a >68K chip with custom microcode to interpret 370 machine instructions >so you could run MVS software on your x86 PC. > >Ok, enough reminiscing for one day. > > <mike Are you one of those original hardware hackers that made new opcodes by rewiring large circuitboards on $10Million IBM mainframes or...?? I can't decide whether to be humbled or perplexed or both. Um. Ya. _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?F180HB3pHoWD47yicBo00003902>