Possible new default wallpaper for your PiDP-11 desktop

[terri-...@glaver.org]

I spent a bit of time cleaning up the best available scan of a good picture of an an actual PDP-11/70 and peripherals. See the last paragraph for the image credits.

I now have it in a 1920 x 1080 image suitable for use on your PiDP-11 (or anywhere else you like). You can download it from https://www.glaver.org/PiDP-11/new-wallpaper.jpg

Once you have it on your PiDP-11, you can install it with the command:
pcmanfm --set-wallpaper new-wallpaper.jpg --wallpaper-mode=fit

If you want to go back to the original rendered wallpaper:

pcmanfm --set-wallpaper /opt/pidp11/install/wallpaper.jpeg --wallpaper-mode=fit

Of course, if you want to use it on something other than a Raspberry Pi, feel free. The commands to set the desktop wallpaper will vary by operating system. I also have a larger version (3050 x 1715) if you need a version for a larger desktop.

I think that the desktop icons look better on the right, where they are not cluttering up the tape drive. I'm attaching a screenshot of my current desktop for reference.

I'm interested in feedback on this - do you like it or not? If so, should it replace the rendered wallpaper or be an option?

The picture came from the back cover in the individual page scans from "PDP11/70 Processor Handbook 1977-78" (yes, there really is no "-" in the name). This was at the Internet Archive, credited to Bitsavers. However, Bitsavers only has the lower-resolution version in their PDF of the manual.

[terri-...@glaver.org]

Here is a much wider angle view, used in the "Digital introduces  PDP-11/70" poster:

It's time to play "name that hardware"...

Here's my guesses:
* Four LA36 DECwriter II
* LP05 line printer
* VT52

* Two TU10 tape drives

* Two RK05F disk drives (not sure about this)
* Something between the upper and lower RK05F drives - what appears to be a regular blank panel has two rows of vent slots

* PDP-11/70

* Two H960 cabinets with MJ11 memory, potentially up to four MJ11 per cabinet 

* Three (one partially out of frame) RP04 disk drives (not sure about this, but RP05/06 has a more swoopy white control panel)

This was obviously a posed publicity shot as it would be impossible to get to the LP05, and the RP04 drives prevent the H960 front doors from opening.

Here is a closer view of the VT52 and 11/70, with an RK05F (?) and the mystery vented blank panel above it:



What is interesting is that the 11/70 front panel lights are identical between the Handbook cover, the "Introduces" poster, and the above close-up. So either all of the pictures were taken at the same time with a CPU running a tight loop - RUN is on in all three pictures (but with the VT52 moved around and the disk pack also moving between the VT52 table and the RP drive closest to the CPU) or this was actually a dummy 11/70 front panel with some lights hardwired on.

[pbi...@gmail.com]

* Something between the upper and lower RK05F drives - what appears to be a regular blank panel has two rows of vent slots

That's the standard front panel for a BA11-K being used for Unibus extension from the CPU chassis.  You'll see them from time-to-time in PDP-11 system photos but the grill doesn't always show clearly and the panel looks blank.  OTOH I suspect that in many cases actual blank panels were in use for lightly-populated BA11-K.  I was surprised the first time that I encountered one of these as they don't seem to be that common, at least when compared to the plethora of blank panels used as rack fillers to keep the vertical rack plenum intact (and look nice too, of course).

[Johnny Billquist]

On 17/02/2026 09.11, terri-...@glaver.org wrote:
> Here is a much wider angle view, used in the "Digital introduces
> PDP-11/70" poster:
>

> Digital Introduces PDP-11_70.jpg
>
> It's time to play "name that hardware"...

:-)

> Here's my guesses:
> * Four LA36 DECwriter II

Check.

> * LP05 line printer

Can't really tell. Some lineprinter for sure, but several of them look
the same. Quality of image isn't good enough for me to say anything more.

> * VT52

Oh yes.

> * Two TU10 tape drives

I would venture TU16, but it could be either. They are more or less the
same drive, just different interface. But since we have an 11/70, I
would generally vote for Massbus. :-)

> * Two RK05F disk drives (not sure about this)

I'd say yes.

> * Something between the upper and lower RK05F drives - what appears to
> be a regular blank panel has two rows of vent slots

I can't even see that on my screen. But some expansion boxes did have
slots in the panel for improved airflow.

> * PDP-11/70
> * Two H960 cabinets with MJ11 memory, potentially up to four MJ11 per
> cabinet

Yeah. I don't see any MK11 control panel, and besides, this was probably
before the MK11 was introduced. Considering that there are two cabinets
to the right, it would suggest more than four MJ11 boxes. (And since
it's a show piece, of course it should be maxed out with eight MJ11. :-) ).

> * Three (one partially out of frame) RP04 disk drives (not sure about
> this, but RP05/06 has a more swoopy white control panel)

Definitely not RP05/06. And it's not RP02/03 since I don't see any RP11
controller. And again - I would vote for Massbus, and yeah, the RP04
looks like that (as far as I can remember, the RP02/03 also look like
that, which is why I mention them).

> This was obviously a posed publicity shot as it would be impossible to
> get to the LP05, and the RP04 drives prevent the H960 front doors from
> opening.

I can't even say what the distance between the disk drives and the
memory cabinets is.
As for the lineprinter, the paper came out at the back, as far as I
remember, so it would be ok where it is.

> Here is a closer view of the VT52 and 11/70, with an RK05F (?) and the
> mystery vented blank panel above it:
>

> Pdp11-70.jpg
>
> What is interesting is that the 11/70 front panel lights are identical
> between the Handbook cover, the "Introduces" poster, and the above
> close-up. So either all of the pictures were taken at the same time with
> a CPU running a tight loop - RUN is on in all three pictures (but with
> the VT52 moved around and the disk pack also moving between the VT52
> table and the RP drive closest to the CPU) or this was actually a dummy
> 11/70 front panel with some lights hardwired on.

The front panel is set to "Super D" and "Data path". Interestingly
enough, the picture of the front panel in the PDP-11/70 Handbook from
1977 (both front and on page 10-18) have almnost the exact same light
pattern as well (it's different on the Super/Kernel/Data lights). It at
least smell of intentional setup. But they might indeed just be running
some code that cause that exact pattern stable. But it is kindof
suspicious that in the picture you posted here, both Super and Kernel
are lit up. But it could be switching between the two rather fast.

Johnny

[Lawrence Fisher (RealTimeCat)]

It could be the photographer could not get a good shot with the lights in action and requested that they HALT the system.

[Johnny Billquist]

In which case the RUN light should be off...

Johnny

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[terri-...@glaver.org]

On Tuesday, February 17, 2026 at 5:16:32 AM UTC-5 b...@softjar.se wrote:

On 17/02/2026 09.11, terri-...@glaver.org wrote:
> * LP05 line printer

Can't really tell. Some lineprinter for sure, but several of them look
the same. Quality of image isn't good enough for me to say anything more.

Definitely a Dataproducts 2200-series drum printer. As to which model badging

DEC put on it, I don't know. It might be different depending on the underlying 2200

model as well - the LP25 is a Dataproducts B300, while the LP26 is a Dataproducts

B600. There's no way to tell without seeing the badges.

> * Two TU10 tape drives

I would venture TU16, but it could be either. They are more or less the
same drive, just different interface. But since we have an 11/70, I
would generally vote for Massbus. :-)

True. I'm not that familiar with DEC's older tape drives - I had 3rd-party drives

(anybody ever hear of Anritsu?) up to the TU77/78 and TU80/81/81+. 

> * Two RK05F disk drives (not sure about this)

I'd say yes.

> * Something between the upper and lower RK05F drives - what appears to
> be a regular blank panel has two rows of vent slots

I can't even see that on my screen. But some expansion boxes did have
slots in the panel for improved airflow. 

Someone else commented that it looked like an older-style Unibus expansion

chassis. Makes sense to put it near the disk drives (and possibly the tape drives

if they were on a Unibus controller).

Here's a close-up with the brightness and contrast fiddled with to make it more

obvious:

> * PDP-11/70
> * Two H960 cabinets with MJ11 memory, potentially up to four MJ11 per
> cabinet

Yeah. I don't see any MK11 control panel, and besides, this was probably
before the MK11 was introduced. Considering that there are two cabinets
to the right, it would suggest more than four MJ11 boxes. (And since
it's a show piece, of course it should be maxed out with eight MJ11. :-) ).

Of course 8-}

  

> * Three (one partially out of frame) RP04 disk drives (not sure about
> this, but RP05/06 has a more swoopy white control panel)

Definitely not RP05/06. And it's not RP02/03 since I don't see any RP11
controller. And again - I would vote for Massbus, and yeah, the RP04
looks like that (as far as I can remember, the RP02/03 also look like
that, which is why I mention them). 

These drives have obvious "Massbus pods" on the sides closest to the memory

cabinets - the control panels on top stop well before the left side of the drive 

(or at least any extensions are black and featureless).

 

> This was obviously a posed publicity shot as it would be impossible to
> get to the LP05, and the RP04 drives prevent the H960 front doors from
> opening.

I can't even say what the distance between the disk drives and the
memory cabinets is.

Yes, the perspective is a bit wonky. But even if the door could be opened,

sliding out the MJ11 chassis would mean that the tech's butt would be

bumping the "Massbus pod" on the side of the drive. 

As for the lineprinter, the paper came out at the back, as far as I
remember, so it would be ok where it is.

Until you need to change the paper carton, or just hit a bunch of form feeds

from the control panel on the top right to get the end of job down into the

paper stacker. 

The front panel is set to "Super D" and "Data path". Interestingly 

enough, the picture of the front panel in the PDP-11/70 Handbook from
1977 (both front and on page 10-18) have almnost the exact same light
pattern as well (it's different on the Super/Kernel/Data lights). It at
least smell of intentional setup. But they might indeed just be running
some code that cause that exact pattern stable. But it is kindof
suspicious that in the picture you posted here, both Super and Kernel
are lit up. But it could be switching between the two rather fast.

It wouldn't have been RSTS/E as that didn't use Supervisor mode until much

later (unless you count the idle job, and this isn't that). RSX? IAS?  Or maybe

am XXDP CPU diagnostic?

[Bradford Miller]

Well I can’t claim to have worked with a system like that one, but I did have a chair exactly like that! Except it was brown.

<Desktop.jpg>

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<Desktop.jpg>

[Johnny Billquist]

On 17/02/2026 21.48, terri-...@glaver.org wrote:
> On Tuesday, February 17, 2026 at 5:16:32 AM UTC-5 b...@softjar.se wrote:
>
> On 17/02/2026 09.11, terri-...@glaver.org wrote:
> > * LP05 line printer
>
> Can't really tell. Some lineprinter for sure, but several of them look
> the same. Quality of image isn't good enough for me to say anything
> more.
>
>
> Definitely a Dataproducts 2200-series drum printer. As to which model
> badging
> DEC put on it, I don't know. It might be different depending on the
> underlying 2200
> model as well - the LP25 is a Dataproducts B300, while the LP26 is a
> Dataproducts
> B600. There's no way to tell without seeing the badges.

I sortof thought the LP25/LP26 would be newer than this, but I could be
wrong. Anyway, those are not drum printers, but band printers (at least
I know the LP25/26/27 are). Similar idea in many ways, but you have a
moving band with types instead of a drum.

I can't even remember what the earlier line printers were. LP04, LP05?
Something like that?

> > * Two TU10 tape drives
>
> I would venture TU16, but it could be either. They are more or lessthe
> same drive, just different interface. But since we have an 11/70, I
> would generally vote for Massbus. :-)
>
>
> True. I'm not that familiar with DEC's older tape drives - I had 3rd-
> party drives
> (anybody ever hear of Anritsu?) up to the TU77/78 and TU80/81/81+.

I've hardly used anything but DEC tapedrives. I do have a TU10 in
storage (used with a PDP-8), and I've certainly used TU16 in the past.
But also just reading the manuals on them. I didn't know until recently
how much the TU10 and TU16 were the same drive.

> > * Something between the upper and lower RK05F drives - what
> appears to
> > be a regular blank panel has two rows of vent slots
>
> I can't even see that on my screen. But some expansion boxes did have
> slots in the panel for improved airflow.
>
>
> Someone else commented that it looked like an older-style Unibus expansion
> chassis. Makes sense to put it near the disk drives (and possibly the
> tape drives
> if they were on a Unibus controller).
>
> Here's a close-up with the brightness and contrast fiddled with to make
> it more
> obvious:
>

> vent slots.jpg

Ah yes. Definitely venting slots so that would be some expansion box.

> > * Three (one partially out of frame) RP04 disk drives (not sure
> about
> > this, but RP05/06 has a more swoopy white control panel)
>
> Definitely not RP05/06. And it's not RP02/03 since I don't see any RP11
> controller. And again - I would vote for Massbus, and yeah, the RP04
> looks like that (as far as I can remember, the RP02/03 also look like
> that, which is why I mention them).
>
>
> These drives have obvious "Massbus pods" on the sides closest to the memory
> cabinets - the control panels on top stop well before the left side of
> the drive
> (or at least any extensions are black and featureless).

I think we all agree on RP04 then.

> The front panel is set to "Super D" and "Data path". Interestingly
>
> enough, the picture of the front panel in the PDP-11/70 Handbook from
> 1977 (both front and on page 10-18) have almnost the exact same light
> pattern as well (it's different on the Super/Kernel/Data lights). It at
> least smell of intentional setup. But they might indeed just be running
> some code that cause that exact pattern stable. But it is kindof
> suspicious that in the picture you posted here, both Super and Kernel
> are lit up. But it could be switching between the two rather fast.
>
>
> It wouldn't have been RSTS/E as that didn't use Supervisor mode until much
> later (unless you count the idle job, and this isn't that). RSX? IAS?
> Or maybe
> am XXDP CPU diagnostic?

If this is back in 1975 or so, then RSX didn't use supervisor either, as
far as I know. I would rather suspect either some diagnostics, or else
something running on bare metal that manipulates stuff as desired.

Johnny

[Johnny Billquist]

On 19/02/2026 16.46, Johnny Billquist wrote:
> On 17/02/2026 21.48, terri-...@glaver.org wrote:
>> On Tuesday, February 17, 2026 at 5:16:32 AM UTC-5 b...@softjar.se wrote:
>>
>>     On 17/02/2026 09.11, terri-...@glaver.org wrote:
>>      > * LP05 line printer
>>
>>     Can't really tell. Some lineprinter for sure, but several of them
>> look

>>     the same. Quality of image isn't good enough for meto say anything

>>     more.
>>
>>
>> Definitely a Dataproducts 2200-series drum printer. As to which model
>> badging
>> DEC put on it, I don't know. It might be different depending on the
>> underlying 2200
>> model as well - the LP25 is a Dataproducts B300, while the LP26 is a
>> Dataproducts
>> B600. There's no way to tell without seeing the badges.
>
> I sortof thought the LP25/LP26 would be newer than this, but I could be
> wrong. Anyway, those are not drum printers, but band printers (at least
> I know the LP25/26/27 are). Similar idea in many ways, but you have a
> moving band with types instead of a drum.
>
> I can't even remember what the earlier line printers were. LP04, LP05?
> Something like that?

Searching around for information, I actually think that is an LP04.
The LP05 and LP01/02 looks different. But that looks very much like the
LP04.
The LP25/26 also look very different, and while from the looks it could
have been an LP27 I think that is way later than these pictures.

Johnny

[Johnny Billquist]

Sorry for almost spamming here... :-)

The LP04 is, by the way, a drum printer. And I think I remember moving
one around once, and it was heavy as hell. We were two persons with
straps over our shoulders to move it around.

Johnny

[Clem Cole]

I did a little digging, looking for images in some DEC documentation as well as a general Internet search, to back up my thinking.

On Tue, Feb 17, 2026 at 3:11 AM terri-...@glaver.org <terri-...@glaver.org> wrote:

* Two RK05F disk drives (not sure about this)

Which is a reasonable guess, but I think they are RS04/RH11 Massbus or maybe RS11/RF11 Unibus fixed disks. 

The reason is that the RK05, including the F (fixed) variant, has the two grey switches for load/unload and write protect, and only has one red light (pic from Google search):

Google Image Search failed to provided picture of an RS04 or an RS11, nor did I find one in the maintenance manuals.  But my guess is that it is one or the other.   I had an RS04 on my 11/70 (the TekLabs system) back in the day, and I also had a single RK05 and an RK05F on an 11/34 at the same time.  My memory is that this picture reminds me of the RS04, which would be my guess.

The tape transports are even more of an enigma.  They are either TU10, TU16, or TE16 and can not be TU77 or TU78 (which both have the tape heads on the right and tape reels on the right); plus, this seems like an early picture of the 11/70.  The TU77 was released in 1979, and TU78 in 80/81.

From Gunkies, the TU77 and TU78

So we need to examine the others.

From page 10 of the EK-TU10-MM-007 maintenance manual, a TU10 looks like this:

From page 18 of the EK-TU16-MM-002 maintenance manual, a TU16  looks like this:

From page 6-4 (171)  of the EK-0TE16-TM-001 maintenance manual, a TE16  looks like 

Although Wikipedia has a better picture:

The TU10 and TU16 are very similar [https://gunkies.org/wiki/TU10_DECmagtape and https://gunkies.org/wiki/TU16_Tape_Transport ].  Both could read/write 7-track at 200, 556, or 800 BPI, or 800 BPI on 9-track.  But from the outside, I believe they look the same, so you can not easily tell them apart in your picture.  If my memory serves me, the TU16 replaced the TU10 on the price list once it was released.

The primary difference between them is the technology used to create the electronics: FLIP chips vs. MSI TTL logic.  I believe that a TU10 could use only the TM11 Unibus interface.  But the TU16 could use the Unibus TM11 controller, or it could also be connected to a TM02 formatter (which in turn was connected to either an RH11 or an RH70 Massbus adapter). 

The TE16 replaced the TU16 and dropped 7-track support in favor of both 800 BPI and 1600 BPI for the 9-tracks; it was implemented with even better electronics.  Also, with the TE16, the DEC peripherals team made a couple of mechanical changes in the tape transport, including another roller guide and a fixed take-up reel, and, most importantly for us as we are trying to identify it, a "Snap-lock" lower hub for easier mounting/dismounting of a tape.

While all three look similar, based on your picture, we can eliminate the newest TE16 because the picture lacks both the fixed take-up reel and the snap-lock hub.   

So the tape transports are either a TU10 or TU16.  Since Terri's picture seems staged as a "glamor" shot, it is not clear whether it would have mattered which one they used.  But for a real 11/70, I would bet on these being Massbus-based with a TM02/TM03 formatter (in fact, I never saw an 11/70 in the wild that did not use the Massbus).

RP style DISKS

I believe you are correct WRT to disks as they are RP04's, as it seems to match the pictures best.  I could not find a picture of the RP01. But the RP02 (which was purchased from Memorex) looked like this:

the RP03 (Sperry Univac dirve - IBM 2311 compatible):

And the RP05/RP06 (DEC branded Memorex 677-01, which Memorex developed in response to the IBM 3340 and 3350) 

I did find a picture of the RP04 (DEC Branded Sperry/Univac ISS 733-10 to compete with the IBM 3330)

And from https://www.columbia.edu/cu/computinghistory/rp04.html

So the last picture seems to best match Terri's wallpaper picture.

The memory is more difficult to trace.  Both core (MJ11) and semiconductor (MK11) are installed into a BA11-K ( which has no indicator lights):

I don't remember if the MJ11 core needs a box controller to set up addressing and interleave.  But the MK11 did need one (shown here):

IIRC (and I might be forgetting), the memory controller is used to set the interleaving and starting address of the cabinet that the MK11 boards are contained in.  I believe that the controller was mounted in the rear of the cabinet, so it would not be visible in this glamor shot.

Finally, the line printers. We can toss out the LG series that looked like the first, as they have no resemblance to the one depicted, as well as the LP25/LP26 band printers: 

as well as the LP27

Looking at the older printers (from the LP11 manual) we see the LP01

the LP02

the LP04

the LP07

the LP10

But your picture shows the controls on the left side, while the controls are on the right side.

So if we eliminate everything else, we are left with the LP05 and LP14.

Like others, I'll suspect that the LP05 (a.k.a. Data Products 2200) is most likely

althought the  LP14 (which I think is a Data Products 2400) might also fit the picture

Since we cannot see the base in the picture, it is unclear which one it is.  Google says the LP14 was released in 1971, and the LP05 was sold between 1970 and 1975.  So I think we need to consider both answers as possible 😉

 

[terri-...@glaver.org]

On Thursday, February 19, 2026 at 10:46:58 AM UTC-5 b...@softjar.se wrote:

On 17/02/2026 21.48, terri-...@glaver.org wrote:
> Definitely a Dataproducts 2200-series drum printer. As to which model
> badging
> DEC put on it, I don't know. It might be different depending on the
> underlying 2200
> model as well - the LP25 is a Dataproducts B300, while the LP26 is a
> Dataproducts
> B600. There's no way to tell without seeing the badges.

I sortof thought the LP25/LP26 would be newer than this, but I could be
wrong. Anyway, those are not drum printers, but band printers (at least
I know the LP25/26/27 are). Similar idea in many ways, but you have a
moving band with types instead of a drum.

I was using the LP25/LP26 as an example of how you can't tell similar

products apart without looking at the badging. They are a lot newer than

the 2200-series model in the picture.

Without looking at the badging, it isn't possible to tell if the printer in the

picture was a 2230 or 2260 .

I can't even remember what the earlier line printers were. LP04, LP05?
Something like that?

I believe that's correct.

 

I've hardly used anything but DEC tapedrives. I do have a TU10 in 

storage (used with a PDP-8), and I've certainly used TU16 in the past.
But also just reading the manuals on them. I didn't know until recently
how much the TU10 and TU16 were the same drive.

Most non-proprietary tape drives ended up using either unformatted

(do everything in your own formatter) or formatted (you can get away

with a bunch of parallel ports to run the drive) Pertec, so they were

generally interchangeable on formatters, as long as the formatter sup-

ported the density and speed of the drive.

Trivia - unformatted Pertec is DTL, not TTL.

Ah yes. Definitely venting slots so that would be some expansion box.

Likely the controller for the disk drives above and below it,
 

I think we all agree on RP04 then.

Yup.

 

If this is back in 1975 or so, then RSX didn't use supervisor either, as
far as I know. I would rather suspect either some diagnostics, or else
something running on bare metal that manipulates stuff as desired.

Supervisor was pretty new, having appeared in the 11-45/50/55 (which are 

all kind of sort of the same CPU) in 1972, and the 11/70 less than 3 years

later, so it is likely that operating systems that needed to support older CPU

models hadn't yet been enhanced to take advantage of it.

I'm leaning toward some sort of memory management diagnostic program.

That would explain the varying brightness of the Supervisor LED and the

near-constant display otherwise, as it buzzed in a tight loop exercising the

sets of PAR/PDR registers.

[terri-...@glaver.org]

On Thursday, February 19, 2026 at 12:39:31 PM UTC-5 b...@softjar.se wrote:

Sorry for almost spamming here... :-)

It's all in good fun... 

The LP04 is, by the way, a drum printer. And I think I remember moving
one around once, and it was heavy as hell. We were two persons with
straps over our shoulders to move it around.

I had a 2230 in my office which had offended me in some manner, so I

picked it up and threw it across the room. And there were witnesses... 

[terri-...@glaver.org]

On Thursday, February 19, 2026 at 5:54:00 PM UTC-5 cl...@ccc.com wrote:

I did a little digging, looking for images in some DEC documentation as well as a general Internet search, to back up my thinking.

On Tue, Feb 17, 2026 at 3:11 AM terri-...@glaver.org <terri-...@glaver.org> wrote:

* Two RK05F disk drives (not sure about this)

Which is a reasonable guess, but I think they are RS04/RH11 Massbus or maybe RS11/RF11 Unibus fixed disks. 

If they were Massbus disks, then they probably used an external controller box, which

might be the unit with vents between the two drives. DEC couldn't implement Massbus-

to-anything adapters in a 10.5" high cabinet with a disk in there as well - look at the

RM02/3/5 cabinet which was the same size as the drive and could hold up to two Mass-

bus adapters (given that the RM02/3/5 were SMD-ish, I don't know why DEC didn't imple-

ment drive select in the Massbus to SMD adapter and let one Massbus controller handle

up to 4 drives). The RP04/5/6 had a "Massbus pod"  which was the height and depth of

the drive and 10-12 inches wide.

Based on this, I'm thinking Unibus disks and a BA11-ish Unibus expansion cabinet in be-

tween the two drives, with system unit(s) of dedicated controllers as opposed to general

Unibus slots.

The reason is that the RK05, including the F (fixed) variant, has the two grey switches for load/unload and write protect, and only has one red light (pic from Google search):

So the RK05F had an actual 2315 pack in there, and just skipped the door?

That's what the above picture looks like. Bizarre.

 

The tape transports are even more of an enigma.  They are either TU10, TU16, or TE16 and can not be TU77 or TU78 (which both have the tape heads on the right and tape reels on the right); plus, this seems like an early picture of the 11/70.  The TU77 was released in 1979, and TU78 in 80/81.

Definitely not TU7x. I had a lot of those (and even more "just passing through"

for depot-level service.

I'm leaning toward TU10/TU16 based on the grey rocker-style switches vs. the

square white button type on the TE16

 The memory is more difficult to trace.  Both core (MJ11) and semiconductor (MK11) are installed into a BA11-K ( which has no indicator lights):

Until the DECdatasystem 570 "corporate" cabinet, large-memory-config 11/70s
often had "naked" chassis (no faceplate, just the alternating purple and white

card guides visible) behind vented H960 cabinet doors (with the air filter foam

stuck to holders on the door panels).

It is unlikely to be MK11 as the preliminary MK11 technical manual didn't come

out until 1978, 3+ years after the 11/70 and thus wouldn't be in the 1977-78

handbook (or the even earlier "Digital introduces PDP-11/70" poster with a pic-

ture of the same system.

Also, even at introduction a single MK11 box could hold 256KW so there would be no need to have a pair of H960 memory racks with 4 MK11 boxes in each.
 

I don't remember if the MJ11 core needs a box controller to set up addressing and interleave.  But the MK11 did need one (shown here):

IIRC (and I might be forgetting), the memory controller is used to set the interleaving and starting address of the cabinet that the MK11 boards are contained in.  I believe that the controller was mounted in the rear of the cabinet, so it would not be visible in this glamor shot.

The MJ11 address and interleave was set on switches on the cards in the MJ11.

lots of chances to damage the ribbon cables pulling those cards out to change

the switches.

The external starting address / interleave on the MK11 was mainly for battery

backup (since people expected the memory to be non-volatile) and since it

needed to be cabled into the  memory cabinet for that, the address / interleave

was moved to the external panel as well. 

 

So if we eliminate everything else, we are left with the LP05 and LP14.

Like others, I'll suspect that the LP05 (a.k.a. Data Products 2200) is most likely

althought the  LP14 (which I think is a Data Products 2400) might also fit the picture

There was a faster-than-600LPM 2200 model which cam with the "acoustic

base" standard. But DEC could well have ordered the 2230/2260 with the

acoustic base option.

Those printers had a bazillion options. One was the vertical format unit,

which could either be basic (form length set on switches), IBM 1403-style

wide paper tape, or the downloadable vertical format unit which actually

had a pair of '181 4-bit bit-slice CPUs, ROMs, and RAM on-board. I hacked

one up for extra RAM and implemented Tiny BASIC in the VFU. Hooking a

keyboard up to the parallel data input MRAC connector resulted in a printer

that could run Tiny BASIC all by itself, with input from the keyboard and 

output on the printer. I even wrote a Mandelbrot program for it before I got

bored and moved onto other things. 

[terri-...@glaver.org]

On Monday, February 16, 2026 at 8:52:21 PM UTC-5 terri-...@glaver.org wrote:

I spent a bit of time cleaning up the best available scan of a good picture of an an actual PDP-11/70 and peripherals. See the last paragraph for the image credits.

So, all the "guess the hardware" fun aside, what do people think of the new wallpaper? Over

100 people have downloaded it already. 

I MIGHT have access to a much better resolution image (original photograph). Research is

ongoing, but probably won't happen for a few months.

[pbi...@gmail.com]

http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-00-HRS4A-A-D%20RS04%20DECdisk%20Service%20Manual.pdf includes multiple illustrations for the RS04.  They are the spittin' image of what we see in the photo.  Figure 1-5 is a close-up of the 3U control panel.  The introductory photo on page 14 of the PDF shows the complete unit, and if you squint a bit it's possible to make out what appears to be the double-row grill in the integrated 6U electronics bay underneath.  There's no accounting for the blank 3U panels above each drive; probably they are simply filler panels.

IMO your memory is sound :-}.

On Thursday, February 19, 2026 at 5:54:00 PM UTC-5 cl...@ccc.com wrote:

I did a little digging, looking for images in some DEC documentation as well as a general Internet search, to back up my thinking.

On Tue, Feb 17, 2026 at 3:11 AM terri-...@glaver.org <terri-...@glaver.org> wrote:

* Two RK05F disk drives (not sure about this)

Which is a reasonable guess, but I think they are RS04/RH11 Massbus or maybe RS11/RF11 Unibus fixed disks. 

...

[Clem Cole]

On Fri, Feb 20, 2026 at 1:53 AM pbi...@gmail.com <pbi...@gmail.com> wrote:

http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-00-HRS4A-A-D%20RS04%20DECdisk%20Service%20Manual.pdf includes multiple illustrations for the RS04. 

Thanks, I missed that manual. Following at home this picture is from same:

 

They are the spittin' image of what we see in the photo. 

Indeed.

 

IMO your memory is sound :-}.

Thank you. 

[Clem Cole]

below:

On Fri, Feb 20, 2026 at 1:36 AM terri-...@glaver.org <terri-...@glaver.org> wrote:

The reason is that the RK05, including the F (fixed) variant, has the two grey switches for load/unload and write protect, and only has one red light (pic from Google search):

So the RK05F had an actual 2315 pack in there

Yes, exactly, but because it was permanently mounted, the drive controller electronics could be more precise, and DEC got twice the normal density. 

, and just skipped the door?

That's what the above picture looks like. Bizarre.

If you look at that picture, you will see 4/5  on the right side of the panel next to the lights and switches.  That is, identifying the single physical RK05F transport as RK05 Units 4 and 5; i.e., the hardware interfaced to the RK11 as two separate standard RK05 units (using standard IBM 2315 compatible disks).  As DEC told you in the maintenance manual, if you swapped out the RK05 disk itself, and mounted it in the RK0F, you had rerun the formatter, as RK0F could not read the disk.  Similarly, if you physically removed the diskand put it into an RK05D/E, it could not read it.

As you note, while this was bizarre, it means any OS that had an RK05 driver [such as Dennis V6 one: https://www.tuhs.org/cgi-bin/utree.pl?file=V6/usr/sys/dmr/rk.c] is unchanged. Of course, UNIX kernel disk-scheduling software can get into a fight with itself when trying to schedule what it thinks are two separate transports.  In the mid 1970s, our Sixth Edition 11/34 had an RK05F, an RK05E, and eventually the first RK07 (that the Pittsburgh Field crew ever saw/installed, and became the first disk driver I ever wrote).  The RK05F was set up as Unit 0 and 1, and the RK05E as Unit 2.   We mounted the root file system / on unit 0, /usr on unit 1, and used unit 2 as /mnt and /users on the RK07. 

As a small sidebar, DEC usually sold DEC-branded, often modified, disk drives and transports from other firms, such as Burroughs, CDC, Sperry-Univac, and Memorex.  I believe the RS08 (fixed disk) was the first one DEC made itself, and the RK series (released on the PDP-8 before the PDP-11) was the first transport with a user-removable drive.