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DEC units on ebay

Hugo Holden

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I saw this on ebay recently:


I have some interest in these though don't know much about their capabilities yet.

The main unit with the front panel switches has an amazing wire wrap board.

But what does the other unit with the plain panel do ? It appears to have a large number of IC's and a power supply, is it Memory ?
 
It's a PDP8/L with a memory expansion box

I expect it will sell for kilodollars
Yes, looks expensive.

What sort of memory is it , is it DRAM, or SRAM , are the IC's still available.... and what sort of capacity would it have ?

...ok 8k

How much memory is in the main unit (if you did not have the expansion box)_ ?

sorry about the long link.
 
What sort of memory is it , is it DRAM, or SRAM , are the IC's still available.... and what sort of capacity would it have ?
It's core memory. Not DRAM or SRAM, not semiconductor memory. There would be 4K of 12 bit words in the 8L box and two more 4K modules in the BM08L expansion box for a total of 12K. Just enough to use many OS8 programs with some sort of block I/O storage device.
I hope anyone bidding on it notices the interconnect ribbon cables have been chopped out. At least the paddles are still there.
 
It's core memory. Not DRAM or SRAM, not semiconductor memory. There would be 4K of 12 bit words in the 8L box and two more 4K modules in the BM08L expansion box for a total of 12K. Just enough to use many OS8 programs with some sort of block I/O storage device.
I hope anyone bidding on it notices the interconnect ribbon cables have been chopped out. At least the paddles are still there.
Wow, it is quite a monster.
 
That showed up on a Facebook group recently with someone asking about it. Note that the interconnect cables are all cut off, so you will have to fix that...

Very cool though, and looks clean other than that. Someone had a really lucky day/find/pick.
 
No, that's the BM8/L expansion box. I know of three in the world. (This one, mine, and one other.)

It expands the basic 4K PDP-8/L on the left, by allowing 20-some slots of *Omnibus* memory to be inserted. The two switches (and corresponding lights) add the necessary field bits and memory expansion circuitry for up to 32K of either core or semiconductor memory.

It is an excellent accessory for that 8/L :).

Vince
 
No, that's the BM8/L expansion box. I know of three in the world. (This one, mine, and one other.)

It expands the basic 4K PDP-8/L on the left, by allowing 20-some slots of *Omnibus* memory to be inserted. The two switches (and corresponding lights) add the necessary field bits and memory expansion circuitry for up to 32K of either core or semiconductor memory.
Looks like 8k 8/I style core memory in the expansion box. Didn't see Omnibus slots in any picture.
https://i.ebayimg.com/images/g/QNYAAOSwXPpjAQCK/s-l1600.jpg
 
Looks like 8k 8/I style core memory in the expansion box. Didn't see Omnibus slots in any picture.
Well, it seems you are correct. The front panel doesnt look like I remember for my BA08 (non-L), and I didn't look closer at the picture enlargements.

Yep, that looks like it's the 12K thing. Still nice, though.

Vince
 
What we have here is not the expansion for Omnibus but rather the regular expansion for a PDP-8/L. It basically puts back everything they took out when making the L from the I: 8KW of core memory, 4 ports for TTYs, at least one A/D and D/A, high speed reader/punch control, scope control, etc. Of course the box supported all that stuff but don't assume any of those features are present since you had to populate the slots accordingly.
What's very unusual about the system for sale is they had the cpu and expansion but mounted them both in the desktop enclosures rather than rack mounting them.

Currently over 2.6K, which I'd still consider cheap. Actually I'd consider that reasonable for either half at this point.

I sold one of these and also one of the Omnibus expansions to James M. years ago, but agree they are very rare, the Omnibus units they also are in a /8-E chassis and have twice as many front panel switches.
 
...
Currently over 2.6K, which I'd still consider cheap. Actually I'd consider that reasonable for either half at this point.
...
The auction still has 5 days to go. I expect it to go much higher at the end. Note also that the reserve price has not yet been met. It will be fun to watch in the last few minutes.
 
The auction still has 5 days to go. I expect it to go much higher at the end. Note also that the reserve price has not yet been met. It will be fun to watch in the last few minutes.
I don't disagree that it could go much higher. The seller could have gotten more interest with a better description and listing which options were installed.
 
...that's the BM8/L expansion box. I know of three in the world. (This one, mine, and one other.)
The BM08 on ebay appears to be serial number 101. It might be the first one to exist. I'm curious what are the serial numbers of the other two.

the 8/L in this bundle is S/N 2919, so kind of late in the 8/L life cycle. The Douglas Jones PDP-8 page says 3902 of the 8/L were made. So, makes me think availability of the BM08 might have been near the end of the 8/L, thus, maybe not so many would have been made
 
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Hugo,

I still have plenty of cards to make up a small PDP-11 if you would like them. We just have to find a cost-effective way to get them to you...

I have a couple of dual height 11/73 CPU cards - one has a broken ROM and the other has a broken SIL resistor pack. You could have both and swap the SIL resistor pack over from the one with the broken ROM. I have plenty of serial and ROM cards. A few memory cards. I should have a disk controller somewhere - but you can use one of the serial ports and a TU58 tape emulator instead. The only thing I am missing is a power supply and a backplane. The power supply can be sourced from a couple of modern switchers - just leaving the backplane and a bit of wiring (DCOK and the like). All of the software is available online.

Not a PDP-8 - but free to a good home. Plenty of support available as well...

Dave
 
Sigh one of my dream unobtainum machines... $3100 so far , thinking it will be what 20-30k? This hobby has gone insane lately, -- look at the 5100 recently.
 
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Hugo,

I still have plenty of cards to make up a small PDP-11 if you would like them. We just have to find a cost-effective way to get them to you...

I have a couple of dual height 11/73 CPU cards - one has a broken ROM and the other has a broken SIL resistor pack. You could have both and swap the SIL resistor pack over from the one with the broken ROM. I have plenty of serial and ROM cards. A few memory cards. I should have a disk controller somewhere - but you can use one of the serial ports and a TU58 tape emulator instead. The only thing I am missing is a power supply and a backplane. The power supply can be sourced from a couple of modern switchers - just leaving the backplane and a bit of wiring (DCOK and the like). All of the software is available online.

Not a PDP-8 - but free to a good home. Plenty of support available as well...

Dave
Dave,

That is a good offer. I have been looking around for a complete PDP-11 with the front panel switches, so your boards would make super good spare parts, but so far I have not been able to find one for sale. I think if I didn't start with a fairly complete unit I would be a little lost, being completely unfamiliar with them. I have never laid my eyes on a working unit, only seen them in photos & movies.

It is interesting how the prices of these DEC computers are so high. But it seems the same thing is happening for many of the very older models too like KIM-1, AIM-65, IBM 5100 and the truly insane Apple 1. One day my IBM-5155 might be worth a fortune.

(On the other hand, I have three 1939 vintage TV's restored and in perfect order with spare NOS CRT's, Of one model there are only 8 or so known to still exist in the World, 15 or so of the other model and about 40 units of the other model. They are rarer than any Violin model made by Stradivari. Even though these are much older and rarer than many of these vintage computers, they don't seem to have the cult following that vintage computers have acquired, and are not as expensive. There are really not enough units of them surviving to support a large hobby group trying to out-bid each other on ebay. Though Post WW2 TV's are becoming quite "active" as a hobby. Or perhaps it is because many people who were familiar with these pre WW2 TV's, in their young adult years and had nostalgic or romantic attachments to them back in the late 1930's, are no longer walking the Earth and the generation/s who followed have little knowledge of them and little interest in them for that reason. It might possibly be that the prices of vintage computers of the 60's to 80's era are going to peak in the next decade and then fall away after that for similar reasons, not that I'm trying to predict the future)
 
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Perhaps we ought to create a separate topic and I will try and educate you a bit before you make a decision?

I have boxes of cards to dispose of (all for a donation to charity) and I know you would get some enjoyment from them. However, don't expect a front panel display though...

Dave
 
The last PDP8/L on Ebay which I can remember was a completely rusted machine and the price was about $9K without any extensions. I thought they would never sell it. Once it disappeared and I asked if they sold it, and they did for that insane price. But it has been on Ebay for a long time... A PDP8/L with only 4K is quite limited. But when you have 12K with the extension it should be possible to run OS/8. So this set has some potential!

To be honest, I'm glad I have started early enough to find some systems for reasonable prices. I'm getting priced out off this market.

(On the other hand, I have three 1939 vintage TV's restored and in perfect order with spare NOS CRT's, Of one model there are only 8 or so known to still exist in the World, 15 or so of the other model and about 40 units of the other model.
Pre war TV sets are a dream for me, I've been collecting radio's and TV's for many years. The oldest set I have is an RCA 621TS. I have also a roundie color TV. It is a prototype color set from 1963
But I wanted to have a pre war set and around 1936 Mr. Kerkhof designed an amateur TV set ans wrote book about it. Not one set is known to have survived the war. So I thought, I can get all get parts. lets built that set because I wanted to see that working. It is a Baird standard TV set with a CRT.

The pre war sets became so costly that I skipped the idea that I will ever own one. But I see many collectors passing away now, or downsizing drastically. So who knows what will come...
 
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