On 22 Jan 2007 at 16:49, Fred Cisin wrote:
The AT started in 1984. Some areas (both geographic,
immediately went for it, and some put it off as long as they could, since
the IBM/MICROS~1 software didn't provide any real incentive to upgrade
other than high density drives and a little faster;
until Windoze 3.1 and OS/2.
More than a little faster, at least to my recollection. Something
like 3 times as fast. 16 bit disk I/O and a CPU with nearly 4 times
the transistor count of the 8088. A lot of folks who bought the
original 6 MHz PC AT discovered overclocking.
While you could find 8 and 9 MHz 8088/8086 systems, neither came
close to a 6 MHz AT in terms of performance. And if you were
adventuresome and clocked that PC AT at 12 or (I've heard it was
done) 20 MHz, the gains were breathtaking--and you had a convenient
place to cook lunch.
One thing that IBM did that really toasted me back then was messing
up on the 8237 DMA controller hookup such that memory-to-memory DMA
didn't work. It could have made the whole business of extended
memory use a lot simpler.