Hi Paul. Who “corrected” you about DMA input? I’d like to read about that as nothing i read about the DZ mentioned that. Got any Cites?
Sent from my iPhone > On Nov 1, 2022, at 09:01, Paul Koning via cctalk <cctalk@classiccmp.org> > wrote: > > > >> On Oct 30, 2022, at 2:49 PM, Wayne S via cctalk <cctalk@classiccmp.org> >> wrote: >> >> The difference between dz and dh interfaces is that the dh used dma instead >> of interrupts to get characters to the cpu. It would be transparent to any >> software. > > No, it doesn't. I was confused about this but was recently corrected. > > The DH11 does DMA output, but not DMA input. I don't know any DEC serial > port devices that have DMA input; it would make very little sense to do that > since input generally is one character at a time. Block mode terminals do > exist in DEC's world but they are rare, and even those are hard to operate > with simple DMA. > > DZ is programmed I/O in both directions, which makes the difference. In > typical usage, the bulk of the terminal traffic is output, so doing that with > DMA is a big win. > > paul > >
