-----Original Message-----
From: Megan <mbg_at_world.std.com>
To: classiccmp_at_classiccmp.org <classiccmp_at_classiccmp.org>
Date: Saturday, February 12, 2000 9:28 PM
Subject: Re: RX01 Bootstrap Loader
>
<snip>>Taken with what you mentioned elsewhere in the message, I suspect
that
>XXDP does PIO while RT uses interrupt-driven IO
That's right. You can set the vector to anything you want (well, almost) and
XXDP will boot and talk to the console - no matter the kind. M9312 will talk
to a single interrupt teletype card as it too does PIO. I find that out
every time I pull out a DL11-W and the vectors get messed up because the dip
switches brush against another board.
DEC *must* have done something for customers who did not wish to upgrade
their old KL11s (M780 cards).
After going through tech notes and FCOs I found that DEC switched from
M780 -> M782 -> M7821 . Since a DL11-B,C,E, or -W can not be installed in
the PDP-11/20 (because no +15V) a decision was made to add a G8000 module
that would filter the 8V lamp voltage and use it as +15, add a couple of
wires.. and a DL11 with EIA could work.
As a result of RT11, DEC produced a new interrupt module M7820 (old one was
M782). The new module handled two interrupts. :-)
I just found a box of them :-) and the PDP-11/20 just booted RT11-V3.0B!!!
and.. I just tried to boot RT11-V4.00 . Boots okay but there is not enough
memory to run Basic. Those MM11-Es are a dogs breakfast. I can live with
tuning 4K of core memory in a PDP-8 but tuning a bunch of core sets in a
pdp-11!??!?! Yuck.
executing "Show All" returns the mini is a "PDP-11/15,20 Processor".. after
that it says "no device 012056". Guess I have to sysgen a 30b and a 4 for
the 11/20s.
>, and without the other
>interrupt working, it won't work. I have an idea of how it could be made
>to, though... contact me off-line...
Thanks for the help...
I am happy that the PDP-11/20s will continue to use the initial KL11 board
set but I will contact you off list so that maybe the original M782 module
can be used.
john
PDP-8 and other rare mini computers
http://www.pdp8.com
>
> Megan Gentry
> Former RT-11 Developer
>
>+--------------------------------+-------------------------------------+
>| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com |
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>
Received on Sat Feb 12 2000 - 23:45:47 GMT