27 Oct
2010
27 Oct
'10
1:57 p.m.
On 27 Oct 2010 at 16:39, Ethan Dicks wrote:
It's the earliest one I am aware of, but my
knowledge of non-DEC stuff
before 1970 is admittedly full of gaps.
Consider, for example, the CDC 7600. Each peripheral processor (or
"channel" in alternative terminology) is hard-assigned a buffer in
SCM. The CPU has no way to talk its channels other than by writing
into these memory-mapped buffers. There are no CPU I/O ports or any
other way for the CPU to reach the outside world. The 6000 series
behaves similarly, but the PPUs get to read any memory address.
Typically, a "mailbox" is set up for PPU communication.
So, did Seymour invent memory-mapped I/O?
I suspect not.
--Chuck