<I seem to remember it being in a Terminals/Comms handbook (which I can't
<find at the moment :-(), where it claimed that the PDT11 was _not_ a
<PDP11, since it didn't have a Unibus/Qbus on it.
Didn't say it wasn't there. Only that at that time for marketing reasons
it was "improper" to call it a PDP-11.
<The PDP11 Architecture Handbook is inconsistent. It describes the 'Two
<PDP11 Expansion Buses' but also calls the PRO300-series 'A PDP11 family
<member'.
As I said. a few years later...
Allison
<In any case, if there was no other problem, feeding it a mistimed signal
<would most likely result in something on the screen - maybe not locked,
<probably not centred. But there would be _something_.
Therein lies the problem.
First the levels form most of the 1861 based designs are poor or sloppy.
The front and back porches are a bit wide. Likely the problem will be
solved when the said cosmac get's it's circuit fixed.
FYI: I have a cosmac design that has the 1861, the driver for the video
circuit was an emitter follower with a series resistor and no load to
ground. When hooled to a hign impedence input monitor (or with with the
75ohm load switched off) it produced no useable output. The fix was chnge
the output stated to have the correct DC offset and self completing. This
in the end was not a VR201 <or any other monitor> problem just a design that
deliberately minimized cost/components with attendant side effects.
Allison
I've got a few unibus cards that I can't find in the various on-line
references, does someone have an early-70's handbook around that could
give me some tips?
G103
G225
G226
M2860
M4801
M7290
Thanks,
Aaron
Hi Gang:
I'm interested in finding a card reader for my pdp-11 machines. There was
one advertised as available earlier this week, unfortunately it has been
claimed.
The CR11 and CM11 models are what I'm looking for - they're a desktop
variety that would work nicely with my current machines.
Anyone out there have one they will part with?
Kevin
==========================================================
Sgt. Kevin McQuiggin, Vancouver Police Department
E-Comm Project (604) 215-5095; Cell: (604) 868-0544
Email: mcquiggi(a)sfu.ca
--- Tony Duell <ard(a)p850ug1.demon.co.uk> wrote:
> OK, you are sure you're giving it 12V still (the VR201 takes its power
> from the system unit when used in a standard DEC configuration).
Yes. I've got a PC PSU attached via my cable (which, again, works with an
Amiga 2000). I even hung a 3.5" HDD off the PSU to ensure a minimum load
on the +5V line to ensure proper +12V on the +12V line.
> Do you get _anything_ on the screen at all, even if you turn up the
brightness
> and contrast controls?.
Yes. I get background signal and a retrace image if I turn it all the way up,
whether the VIP is plugged in or not.
> What does your composite output from the RCA VIP
> look like on a 'scope?
I can see some negative pulses, a stronger line at 0VDC, some schmutz that
looks like video data between the sync pulses. It has the general appearance
of NTSC mono data. When I attach a Commodore 1084S to the VIP, I get exactly
what I expect: digital block noise (from random memory garbage in the VIP at
power on) and 1" tall numbers when I tap commands on the keypad.
> Can it drive the 75 Ohm input impedance of the VR201?
Dunno. How can I tell? I have the VIP schematics. Is there something I
can do with this?
> Is there a large DC offset on the signal?
How would I spot it? The sync pulses are below the 0VDC base line, there _is_
a baseline and the noisy stuff is above the base line. Is that what I'm
looking
for?
There is a mention in the manual about tuning a resistor or two for the sake
of certain brands of RF Modulators. Perhaps the signal isn't hot enough to
tickle the VR-201?
> The VR201s I've looked inside use a standard TDA1180/TDA1170 circuit.
> They should be able to lock to 15720Hz (in fact I think I've had them locked
> to 15625Hz, which is the UK TV horizontal frequency). Even if they
> couldn't, there would still be something on the screen.
There appears to be a beam; there is assuredly heat on the cathode, there is
no VIP data on the screen.
This VR201 works with my DECMate II perfectly well. It also works with an
A2000 w/my custom cable. The VIP works with its own cable to another
composite monitor. The only combination that does not work is my custom
cable between a VIP and the VR-201; that path is what I'm trying to debug.
Thanks,
-ethan
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<Which series is most compact (sized for desktop or tower style) pdp
An 11/53 thats a 11/23 cpu in a BA23 box. About 6Wx28Hx30D and an easy
110v outlet. With a RD52(30mb) and a RX50 floppy you can run most any
PDP11 OS including unix (starting with 2.9 or 2.11).
The other choice is a BA123 (end table) with a 11/23 or 11/73 in it. Fast
and plenty of disk drives, not to hard on power(110V 600Wmax).
If you want something really low power, a PRO350 (or 380) that's a PDP11
or a PDT11/150 (tiny and very low power, less than bigger PCs).
PDP-11 line run from the really big like the 11/70 down to a single board
(falcon card T-11 cpu, 2 serial, Parallel, 2kw ram, rom, one dual card!).
So having a PDP-11 os some sort is very possible and they are all for the
most part PDP-11s differing mostly in speed, IO and maximum memory.
Allison
Before I forget, last week I saw a BA213 with a M9405 and three M9047
in it. The module database at <http://www.neurotica.com/dec-info/>
is down, it appears, and I can't find another link like it right now.
The unit was $20 at the UW-Madison (Wisconsin) surplus SWAP shop,
open Fridays 8 to 2.
- John
What do those things have in common? Apparently not much. I was attempting
to lighten my load for the VCF and I ran across a small problem. I have this
cable I made to use a VR201 with an Amiga. It works. I even tested it tonight
to eliminate sources of failure. When I try to hook a COSMAC VIP up to it, I
get nothing. The numbers (from the RCA 1861 spec sheets) look like this:
NTSC 1861 @ 1.76064 Mhz 1861 @ 1.764000 Mhz 1861 @ 3.579545/2
-------- ------------------ ------------------- -----------------
Line 15750 Hz 15720 Hz 15750 Hz 15980 Hz
Field 60 Hz 60 Hz 60.11 Hz 60.99 Hz
The xtal in the VIP is 3.521280 Mhz (2 x 1.76064 Mhz). It seems that the
VR201 is sensitive to a 30 Hz difference in the horizontal freq. Barring
the chance that I can locate a 3.528 Mhz xtal before the VCF, am I hosed
here? I had hoped on using either my VR201 or one brought to the show by
a kind soul. As it stands now, I'll have to hope for a kind soul to help
me with a standard NTSC monitor (I've just tested the VIP with a more
ordinary Commodore 1084S).
Can any video guru's shed any light on my dilemma? Is the VR201 that
sensitive? Is there a way to get around this?
Thanks,
-ethan
=====
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On Sep 24, 8:48, allisonp(a)world.std.com wrote:
> > the RAM (typically 1.5MB) and its performance is more like an 11/73
than an
> > 11/23. You'd need BSD 2.11 to have any hope of MSCP support for RDxx
or
> > RX50.
>
> Pete,
>
> You forgot to tell him about PUPS! sheesh, even if you not into unix you
> need to add that to your PDP-11 list of good information sources.
>
> ...I'm not home so I don't have the address. ;)
Oops, yes, that's a bit of an omission... see
http://minnie.cs.adfa.edu.au/PUPS/index.html
As (I think) Allison knows, I have an 11/83 running 2.11BSD and an 11/23
running Seventh Edition, as well as several other 11s.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
On Sep 24, 8:46, allisonp(a)world.std.com wrote:
> Subject: Re: PDP 11/70s For Sale
> > No, an 11/53 isn't an 11/23, it uses a J-11 on a board which also
includes
> > the RAM (typically 1.5MB) and its performance is more like an 11/73
than an
> > 11/23. You'd need BSD 2.11 to have any hope of MSCP support for RDxx
or
> > RX50.
>
> Didn't check the MicroPDP-11 book on this one. All the 11/53 boxes I've
> seen either had 11/23B or the earlier no ram-nonPMI 11/73 cpu in them.
> Apparently that was a common configuration or the common path for the
used
> boxes.
The microPDP-11/53 uses a specific 11/53 CPU board design with a J-11,
SLUs, memory, and boot ROMs on one board. There's no reason you couldn't
put an 11/23B in there instead, but 11/53s were never made with F-11
processors, so the ones you've seen must have been downgraded -- or have
had the badge replaced :-) The cabinet is of course the same BA23 as the
microPDP-11/23 and microPDP-11/73.
> in any case most of the 11/23 or 11/73 cpus work quite nicely in
> that box.
They certainly would, of course.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
