25 Sep
2015
25 Sep
'15
11:22 a.m.
On 09/25/2015 09:56 AM, Al Kossow wrote:
What I/O board are you trying to figure out, Eric? A
bunch of
different manufacturers early Multibus Winchester controller boards
used them.
The 8089 was a good idea but badly timed and terribly underpowered. 2
channels of DMA, while a plain old 8257/8237 could give you 4. When the
80186 was being sampled, it too, had 2 channels of 20 bit DMA on-chip,
so why fool with another chip. In the meantime, RAM prices were headed
lower, so having private RAM for an I/O device (e.g. hard disk) made DMA
less important.
Good idea, wrong timing. When I approached "Fast Eddie" our Intel sales
guy, he gave me a bunch of documentation on the 8089 and told me that it
wasn't worth looking into for a design. This was about 1980.
--Chuck