Messages in this thread | | | Date | Sat, 25 Mar 2000 17:04:46 +0100 | From | Ralf Baechle <> | Subject | Re: Patch: BadRAM put to use |
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On Sat, Mar 25, 2000 at 05:47:54AM +0100, Rick van Rein wrote:
> > > I can use 61 MB out of 64 MB, which is a great result, and > > > good for trees. > > With that, I meant environmental matters in general. Being a little poetic. > Chip production is really wasteful on resources, mainly because everything > has to be extremely pure. And every chip has to be 100% correct for > acceptance, which is not strictly necessary for everything, at least not > for RAM chips.
No longer. Many chips are designed with some redundance which allows to achieve a higher yield rate. While still on the wafer the chips are being tested and defectiva parts disabled / replacments activated by some laser beam. Some chips do extensive selftests after powerup after which they deciede how they reconfigure themselfes to look like a perfectly healthy chip. Certain special purpose chips as used for satelites drive this technology to the limit by very high number of redundant units. For the more cost sensitive standard technology like an R5000 microprocessor this is limited to replacability of parts of the cache. Spare ALUs for example would take too much space.
Ralf
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