Anders Johansson wrote:
On Thursday 10 November 2005 14:02, Jerry Feldman wrote:
On Thursday 10 November 2005 12:08 am, Steven T. Hatton wrote:
What I was taught in my course on hardware in college years ago is that some compilers on "RISC" processors skipped assembler, and wrote in a more cryptic instruction set which was virtually impossible for a human to make sense of. The assembler instructions for such systems is written as a "higher level" language. Most modern compilers generate their code directly rather than calling the assembler.
This is true, but I suspect Steven is talkiing about microcode. Microcode is the stuff the CPU really understands, and assembly (or machine language, which is a one-to-one translation of assembly code, not counting the administrative stuff, and the occasional macro) gets translated to microcode on the fly. This is true for most modern platforms, and especially for AMD. I'm told AMD actually implements the Intel compatibility on top of their native microcode
I'd love to see a linux version written directly to the native AMD core :)
If you are AMD, you understand that Intel is likely to unleash some features to render your hardware obsolete in a timeframe that you can't react to speedily enough, with the need for redesigning and retooling, so recoding in microcode gives you the ability to swiftly respond. For years that's how we at Amdahl were able to stay with the twists and turns by IBM that were designed to kill us off. When IBM started off on that road, we didn't have microcode, so we had to add a FAM (Fast Assist Mode) so that when the new instructions generated an exception, they could be emulated by substituting a series of software instructions - so Microcode and Macrocode appeared in our succeeding products. An ex-colleague remarked last week how amazing it is that the latest greatest stuff like Xen has been standard on mainframes (Amdahl MDF followed by IBM LPAR's) for decades. Eventually IBM got us, not by technology, but by nearly going under themselves. Regards Sid. -- Sid Boyce ... Hamradio License G3VBV, licensed Private Pilot Retired IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support Specialist Microsoft Windows Free Zone - Linux used for all Computing Tasks