Jun 4, 2020, 12:00:03 PM6/4/20
On Wednesday, June 3, 2020 at 4:50:33 PM UTC-7, Steve Tockey wrote:
> To be precise, if you are running a 1.2 uSec cycle time ...
Sorry, I should clarify that my PDP-8/A has a KK8E CPU. An 8/E CPU in an 8/A chassis was an official DEC configuration, the 8A600 and 8A800 family. So, unless memory interferes, it's the same speed as an 8/E.
The real question is whether the MS8C or D can ever delay the CPU for a memory refresh. From the manual it appears that the C or D versions have a transparent refresh cycle that fits into time when the memory would otherwise be idle, so the CPU is never forced to wait.
At least that's the theory. I haven't really found a definitive statement about this, or about TD8E compatibility in general. I know that the timing is very tight for this peripheral, and there's not much margin for delays.