17 Nov
1997
17 Nov
'97
4:11 a.m.
Well, what did the PC/AT have that the PC/XT
didn't? 1.2MB
minifloppies (although I saw those retrofit onto XT-class PCs), 16-bit
slots, a cascaded interrupt controller to handle the additional
interrupt request lines...and the A20 gate that let you get at another
little chunk of RAM up above the 1MB boundary while still in real
mode.
...and the hard drive info in ROM.
But, you're right. The 286-386 jump was more significant than the 8088-286
jump, even though so of those 286 changes that you mentioned are still with
us that Pentiums are "AT" (not 386) class machines.