A while ago there was some discussion on the question of the N64's bilinear filtering and whether or not it was "true" or a hack method. The details of the shortcut used (which was still very, very good IMHO esp. c.f. competitors) are detailed in Nintendo's patent for the system on the US patent web site. The whole document is quite interesting, although it doesn't read very well.
http://patft.uspto.gov/netacgi/nph-...,239,810.WKU.&OS=PN/6,239,810&RS=PN/6,239,810
"For hardware cost reduction, display processor texture filter unit 532 does not implement a true bilinear filter. Instead, it linearly interpolates the three nearest texels to produce the result pixels. This has a natural triangulation bias which is not noticeable in normal texture images but may be noticed in regular pattern images. This artifact can be eliminated by prefiltering the texture image with a wider filter."
http://patft.uspto.gov/netacgi/nph-...,239,810.WKU.&OS=PN/6,239,810&RS=PN/6,239,810
"For hardware cost reduction, display processor texture filter unit 532 does not implement a true bilinear filter. Instead, it linearly interpolates the three nearest texels to produce the result pixels. This has a natural triangulation bias which is not noticeable in normal texture images but may be noticed in regular pattern images. This artifact can be eliminated by prefiltering the texture image with a wider filter."
