[GreenKeys] Using ASR 33 with PDP 11/05

Wed Mar 16 02:21:39 EDT 2011

Excellet, and I'm glad to be of service.

Though, personally for a "desktop" PDP-11, I would probably go for a
QBUS 11/23+ in a BA11-M enclosure; you get your CPU, two SLUs and boot
ROM on one card, and an MSV11-QC 4MB RAM card in a second set of quad
backplane slots. The remaining two quad width spaces let's you add
either 2 quad width modules, 1 quad width module and 2 dual-widths or
4 dual-width modules. So, in a "real" system I'd probably load up an
RLV12 and probably a DELQA Ethernet card in the last two slots, giving
you a nice internet connectable desktop system. And you can stick it
in a nice short rack and have a deskside system like so:
http://hampage.hu/pdp-11/kepek/1123PLUS.JPG  Now, using a modern PC, I
would probably forgo the RLV12, and instead replace the KEF11 floating
point chip on the KDF11-B CPU with the FPF-11 FPP card, still keeping
the DELQA. Have a dirt cheap PC (running whatever OS you choose) as
terminal emulator (connected to DL0:) and a TU58 emulator (DL1:)
hosting oversized TU58 tape images (oversized to about the size of an
RL02 drive). Sure it's not a "wholly PDP-11" system, but the point
remains that such a system gives you a "perfect" RT-11 desktop (and
you also have a desktop PC so you've a nearly perfect system for cross
platform development).

Another nice "desktop" PDP-11 would be the one that I'm in the process
of getting my hands on. It's a VT-103, which is a VT-100 with a
H9281-BA (dual width, 4 slot, 18-bit QBUS) backplane (or equivalent to
it), installed inside a VT-100 terminal chassis with an 18-bit QBUS
processor installed, as well as standard 2 line SLU card, a third
party disk interface (with disk!) and a bit of memory. And I believe
mine - like some VT-103's - has the installed TU58 drive, which
connects to SLU port 2, and the processor is probably an 11/03 or
early 18-bit 11/23 card. Then again, the VT-103 may have been "pimped
out" by the user and improved with a 22-bit QBUS backplane, so it
could then use any dual-width QBUS processor card. Still limited in
terms of space though (unless one gets an expander box... which kind
of negates the reason for the VT-103 in the first place).

But I digress.

I assume you've taken a look through the BitSavers documentation
regarding the 11/05 and 11/10 (which are the same system, save one is
OEM and the other is the 'normal' one, I don't remember which though).
Also, going on information from the site of another restorer of an
11/10, the other two lines of the six line cable aren't "just grounds"
but in face are External Clock and Internal Clock Disable; which -
other then having self-explanatory (to me at least) names - allow one
to disable the internal clock of the KL11 and use an external source,
perfect if you want to go faster or slower then the range of speeds
afforded by the internal clock adjustment potentiometer. (For example
you'd use an external clock signal if you wanted to plug your
PDP-11/05 into a cheap desktop running at 9600 baud; or you could use
an external clock to make sure a that the 110 baud is /really/ 110
baud not faster or slower.) For you, I'd say simply ignore said
external signals (though, perhaps ground them to make sure Stuff
Doesn't Happen), and just play with the adjustment pot until your SLU
is putting out a nice, perfect 110 baud (use a scope), and then adjust
your teletype to the 11/05 so that both "play nice" when put to use.

And finally, as one VERY important thing to remember, if/when you
toggle in a papertape bootstrap, make sure you use the correct one
(otherwise your 11 will be doing nothing fast.)

Cheers, and I hope this helps you some.

On 15 March 2011 00:28, B Degnan <billdeg at degnanco.com> wrote:
> Thank you so much for the information, I got both messages and I found them
> useful.  That link you sent is very useful.  The unintended consequence of
> restoring a pdp 11/05 is the experience of restoring a teletype and learning
> a lot about it too.
>
> Why the 11/05?  I like the idea of a "desktop" pdp 11, a simple 8K personal
> computer with teletype for printout/display/input/storage.   I agree an
> 11/40 is more useful, and that something like that I'd rather use drives and
> a terminal than a teletype.  I don't have a high-speed reader.
>
> So if I get your message, I should only need a 4-wire connection.  Or at
> least try that, and see if I can load a tape, make a memory dump tape, and
> that sort of thing.  Also send a print to the screen, echo characters, etc.
>
> Best,
>
> Bill Degnan
>
>
> At 12:13 AM 3/15/2011, you wrote:
>>
>> As a corollary which just crossed my mind - due to the fact I just
>> noticed the link to the wiring diagram of the cabel between the DL-11
>> and the ASR-33/ASR-35 - the extra two pins in the DEC cable seem to be
>> glorified ground connections (if I can make out the table correctly),
>> while all you need are the four "standard" lines of TxD+, TxD-; RxD+
>> and RxD-.
>>
>> Also, sorry for the extremely short post.
>
>
>