DEC PDT-11/150

[mechaniputer]

Hi everybody,

There's a DEC PDT-11/150 a few hours away from me. Good condition, probably works, but there's no boot media. It takes the 8" floppies. It seems uncommon and I'd like to add it to my collection for posterity.

The thing is, it's hard to justify it if I can't make it do anything, especially given the size of it. If I go get it, what could I do with it? I don't have any 8" floppy disks and even if I did, I'm not sure how I'd put an OS onto one. Is there a way I could use some modern hardware to emulate the drives? Does it have an onboard (ODT-style) serial monitor to at least dump assembly programs to it from a PC like I've done with my (still driveless) 11/73?

And regardless of whether I decide to get it, I'd love to hear any anecdotes or trivia about this machine since I know very little about it.

Thanks.

 

[mcguire]

Hi everybody,

There's a DEC PDT-11/150 a few hours away from me. Good condition, probably works, but there's no boot media. It takes the 8" floppies. It seems uncommon and I'd like to add it to my collection for posterity.

The thing is, it's hard to justify it if I can't make it do anything, especially given the size of it. If I go get it, what could I do with it? I don't have any 8" floppy disks and even if I did, I'm not sure how I'd put an OS onto one. Is there a way I could use some modern hardware to emulate the drives? Does it have an onboard (ODT-style) serial monitor to at least dump assembly programs to it from a PC like I've done with my (still driveless) 11/73?

And regardless of whether I decide to get it, I'd love to hear any anecdotes or trivia about this machine since I know very little about it.

It will run RT-11. Bootable RT-11 disk images are easy to find, and easy to generate using simh. You can write them to physical disks with the right setup on a PC. Many people here have that capability and can likely help you out.

You're correct that the PDT-11s are quite rare. I had two about 35 years ago, and deeply regret having sold them at the time. They're one of the few major examples of PDP-11 implementations that we don't have on exhibit at LSSM.

-Dave

 

[saipan59]

Hi everybody,

There's a DEC PDT-11/150 a few hours away from me. Good condition, probably works, but there's no boot media. It takes the 8" floppies. It seems uncommon and I'd like to add it to my collection for posterity.

The thing is, it's hard to justify it if I can't make it do anything, especially given the size of it. If I go get it, what could I do with it? I don't have any 8" floppy disks and even if I did, I'm not sure how I'd put an OS onto one. Is there a way I could use some modern hardware to emulate the drives? Does it have an onboard (ODT-style) serial monitor to at least dump assembly programs to it from a PC like I've done with my (still driveless) 11/73?

And regardless of whether I decide to get it, I'd love to hear any anecdotes or trivia about this machine since I know very little about it.

Thanks.

Yes, the PDT will do ODT at the terminal. The chipset is the same as the LSI-11.
But NOTE that there's not much upgrade/modification possibility with the HW. There is no backplane; almost everything is on a single large PCB. As I recall, the only "interface" you have easy access to is RS-232. To me, this makes it a lot less interesting.

Historical note: PDT systems were offered for sale to employees for a relatively low price. The "story" was that DEC had designed and built a bunch of them, but then the expected market for them fizzled. So they did the employee sale to get rid of them.
I had one, and used it to play with Fig-FORTH for awhile, but eventually lost interest in it because the HW was so restricted.
IIRC, the employee sale also bundled it with a VT-52, which was also obsolete at the time.

Pete

 

[tradde]

Hah, sell your old obsolete equipment to your employees. I am sure other companies did similar things though.

 

[m_thompson]

General Motors dealerships used to have two PDT-11s. One for ordering cars, and one for ordering parts.

 

[leegleason]

Hi everybody,

There's a DEC PDT-11/150 a few hours away from me. Good condition, probably works, but there's no boot media. It takes the 8" floppies. It seems uncommon and I'd like to add it to my collection for posterity.

The thing is, it's hard to justify it if I can't make it do anything, especially given the size of it. If I go get it, what could I do with it? I don't have any 8" floppy disks and even if I did, I'm not sure how I'd put an OS onto one. Is there a way I could use some modern hardware to emulate the drives? Does it have an onboard (ODT-style) serial monitor to at least dump assembly programs to it from a PC like I've done with my (still driveless) 11/73?

And regardless of whether I decide to get it, I'd love to hear any anecdotes or trivia about this machine since I know very little about it.

Thanks.

If you wind up getting this system, let me know. I can provide some software for PDT-11/150s.

 

[czunit]

I have a pair of pdt11/150's. Oddly enough it's a very nice little computer, a lot better than an 11/05 hulking under your marimba. And as a good compact pdp11 it's a functional equal to a pdp11/V03.

The oddest thing is the disk controller: Instead of being DX: driver it's PD: driver so when you make a boot disk on an rx01 equipped pdp11 you have to init/sys/deviceD and make sure the pd.sys driver is on there.

But for a nice little RT11 machine it can't be beat: 11/03 CPU, EIS and FIS, 30kw of usable memory, and three extra serial ports (I should try it with MUBASIC), printer port, and of course a full RS232 port for a modem.

 

[smj]

The PDT-11/150 is a perfectly cromulent PC. Was it ever sold without the second floppy drive? I can't remember if the case was setup to (theoretically) allow for that or not...

 

[saipan59]

>Was it ever sold without the second floppy drive?

I don't believe so. However, there was a PDT-11/130 and 110. The 130 is a VT-100 with an LSI-11 CPU inside, plus a dual TU-58 tape drive. Very much like a VT-103, but without the Qbus backplane inside. The 110 is lacking the TU-58, and has nothing but serial ports.

Pete

 

[czunit]

Oddly enough it could be: I have the second drive off on my second 11/150 and it looks fine. If they had built it with a 20mb hard disk it would have been unstoppable.

 

[acollins22]

Hi,

I have a PDT-11 but I can't remember the sub-type and it has a second 8" drive.

Sadly, mine isn't booting. It's on the "Shelf of good intentions" awaiting my attention.


Cheers,

Andy.

 

[DDS]

I like "Shelf of good intentions"

Sadly, I have a garage of good intentions.

"Between the idea
And the reality
Between the motion
And the act
Falls the Shadow" -- T. S. Eliot​

 

[m_thompson]

I was in the RICM warehouse a few weeks ago and took this picture...

 

[Henk]

That stack would be "hurting" the one at the bottom.The PDT-11/150 weighs a few kilos ...
Maybe it is the lighting, but these PDTs look like they have very little "yellowing".
The PDP-11/150 hat I have certainly is not as white as these in the picture.

 

[Agent Orange]

Looks like there are only 4 units per tier.

 

[czunit]

Still, the tops are plastic. Oh well, they are nice little systems. Another issue I noticed is that the sector LEDs are going dim, need to be replaced.