On Wed, Mar 07, 2001 at 11:57:44AM +0100, Erdmut Pfeifer wrote: | | This A20-line crap rates as one of the most insane ideas ever put forth | in the whole history of PCs. Anyone who doesn't know already may want to | read up a little on what it's about, for example here | | http://www.phys.uu.nl/~mjanssen/control.php3?chapter=6 | http://www.phys.uu.nl/~mjanssen/control.php3?chapter=9 | (a google search for the exact phrase "A20 line" will turn up a couple | of more links) | | In short, it was born in a desperate attempt at gaining another 64k | (k!) of memory addressable beyond the 1M limit of the so-called "real | mode" of 80x86 processors. It was realised by introducing some weird | mechanics into the PC hardware that allows to switch that special | addressing scheme on or off. | It's one of the prototypical examples of how an ad-hoc solution of no | real benefit can cause headaches for thousands of people. Even years | after its invention it seems to haunt innocent users. Unbelievable! |
Oh, interesting. Some more details in how bad the design of the x86 architecture was/is. In my Into to Assembly class we used M68K processors. The prof spent 1 day giving an overview of the layout of the x86, and I was really glad then we weren't using x86 systems! The only advantage I can think of is Pentiums are current and fast while m68k is a dead (as in nothing new happending) product line. Does anyone have any overviews/comparisons of Sparc and Alpha designs? What about ARM? I don't know much (anything realy) about ARM and where it came from or who made it. I'm really more of a software guy, but I find the hardware to be interesting as well. | -- Bugs come in through open windows. Keep Windows shut! -- Nice. -D
