21 Oct
2005
21 Oct
'05
7:58 a.m.
>>>> "Allison" == Allison
<ajp166 at bellatlantic.net> writes:
> Subject: Re: RL01 drive select plug and power
supply questions
> From: Johnny Billquist <bqt at Update.UU.SE> Date: Fri, 21 Oct 2005
> 13:16:33 +0200 (CEST) To: cctalk at classiccmp.org
>
> I think I'll slightly disagree with you here. While all you say
> is essentially true, the DLV11 is a tremendour burden on the
> system compared to the DHV11. So if you actually want to run
> serial connections to a machine, keep the DHV11, and don't use the
> console more than absolutely neccesary.
>
> Big difference between DMA and interrupts you know...
Allison> Yes I do. However for a single user system the load is not
Allison> an issue. If your running a timeshare system such as RSTS
Allison> or RSX with more than one user then DHV11 sense as well.
Not true. 9600 baud is 960 interrupts per second, on a character I/O
device. That's a big number for a PDP-11. Output will be
significantly less of a burden with a DH type output controller than
with other types -- even for just one active terminal.
Allison> For most of my 11s four lines is the limit for what I can
Allison> seem to keep busy. Figure a user terminal, LA100 Printer
Allison> and serial line for modem or data line to another system. At
Allison> the extreme I've run two terminals for OSs that support that
Allison> but, I can only type on on at any instant. ;)
Sure, if you're mostly doing editing, then the CPU burden of high
speed output may not be obvious. If you had an LN03 or similar
printer, you might see it more easily. An LA100, of course, isn't
much of a problem because it is quite slow.
paul