On 2015-04-26 22:14, Cory Smelosky wrote:
On Sun, 26 Apr 2015, Johnny Billquist wrote:
All true and good points.
I'm curious on exactly how a DEUNA/DELUA works in a KS-10. Does anyone
know? Does it do 8-bit-byte DMA to the 18-bit memory, leaving the top
two bits alone. Or does it only work if it do word DMA (would be
strange, as the controller itself can send and receive odd byte length
ethernet packets).
And how does the whole controller actually work in a KS, since the
controller expects there to be control structures in memory, which are
used to manage the buffers. Those are expected to be 16-bit fields at
one address, and an additional 2 bits of address in another word.
Is there some potential problem with regards to a PDP-11, which have
two parity bits for data, which are used for actual data on a KS? (If
I remember right.)
How does the DZ do it? THAT I know is a supported.
Haha... DZ don't do DMA. :-)
There is a reason it is a very disliked peripherial...
In short, this
is not trivial, and if it works on a real machine, the
emulation needs to reflect that truthfully, or else it will not be so
useful. I suspect it should work on a real machine, as hints suggested
that it was at least considered.
Could always do "emulation mode" and "real hardware mode".
Definitely doable, but if you go down that path, why even make it
somewhat similar to a DEUNA/DELUA? Then you might as well provide a
controller with way more functionality...
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol