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PDP-8/M on eBay

It caught my eye, too. I really should avoid such temptations until I've made a lot more progress on my PDP-11/44 project, but will my willpower be strong enough? :)

I don't know how to tell from the pictures whether it's complete enough to run, how much memory it has, what peripheral interfaces it has, etc., since I still just have my nose against the window of the PDP-8 shop and don't have any real experience with them yet. I gather that the PDP-8/M is "less expandable" than the PDP-8/E form what I've read, but I don't have a feeling for what that really means yet.

Whether I end up adopting this one or not, I'd find it interesting and educational if any PDP-8 experts can offer opinions about this particular machine. I think I'll grab the listing pictures for later reference.
 
Looks like a bare bones machine with 8kW of core and one TTY interface.

What are the Y083/084/111 yellow handle cards? What are yellow handle cards?

The 50/51 interfaces are marked "ACS 272". I wonder what they were...

Lou
 
Hi All;
Lou, I see SomeOme finally placed a Bid.. So the Big Question is -- Does what He want for it a Fair Price or is He whistling up His 8.. I couldn't even afford the Shipping, not to say anything about the machine itself.. All I can say is I hope SomeOne we know gets it..
THANK YOU Marty
 
Inquiring minds want to know: What is a fair price range for a PDP-8/M these days?

I'm still a bit stunned from recently learning how much a PDP-12 system sells for.
 
Marty said:
Hi All;
Lou, I see SomeOme finally placed a Bid.. So the Big Question is -- Does what He want for it a Fair Price or is He whistling up His 8.. I couldn't even afford the Shipping, not to say anything about the machine itself.. All I can say is I hope SomeOne we know gets it..
THANK YOU Marty
Click to expand...
Seems a bit high, but it's eBay. I don't know what the yellow handle cards are.
 
It's impossible to say if it's a "fair" price, because we all have different opinions of what is fair (if "fair" even applies here, since we don't "need" to buy this.)

However, I would say that this does seem to be the going price, the price that the market will bear. As with Marty, I am not in that market either.

As another check, it does seem that this whole assembly's price seems to be in line with the sum of the ebay prices for the individual parts.

Lou
 
I thought the 12 would sell for $10K and I was wrong. If you asked me about an 8/M last year I'd think no more than $1500, without any cage. This year I am starting to think that prices of these are going up.
b
 
NF6X said:
I gather that the PDP-8/M is "less expandable" than the PDP-8/E form what I've read, but I don't have a feeling for what that really means yet.
Click to expand...
The box is physically shorter. It only fits one Omnibus backplane. The 8/e fits two. If i recall correctly one backplane is 20 slots. A basic PDP-8/e or 8/m would have 1 slot taken for the front panel, 4 slots for the basic CPU, 3 slots for each board of core memory (either 4kW or 8kW). You probably want a serial interface, that is 1 slot, you also need a 1 slot RFI shield between memory and other cards. So that is 10 slots for a very basic system. Extended memory requires "Extended Memory and Time Share Control" which is one slot. You might want "Extended arithmetic element" which is 2 slots. This leave you with 7 slots for more memory and peripherals. If you satisfy with an RX floppy controller you could put two extra sets of memory in there, for a maximum of 24kW. Not at all a bad machine. But if you want an RK05 controller and full 32kW of memory, you need another backplane.

(I'm no expert in configuring the PDP-8, I might very well have missed details. This was just to give a hint of what available/needed)
 
billdeg said:
I thought the 12 would sell for $10K and I was wrong. If you asked me about an 8/M last year I'd think no more than $1500, without any cage. This year I am starting to think that prices of these are going up.
b
Click to expand...
I was pretty sure the pdp-12 would sell in the mid teens if not higher. My pdp-8i sold many years back for $15k (although it did go with lots of neat stuff - TC08, RK02(2), RK8 (control for disk), TU56, DF32s (2), PC01, and lots of spare flipchips, all that in 4 racks). If I had not needed the money to fix my house so it would sell I'd still have it. It is now part of the Paul Allen collection where it has a good home. Some day I hope to get up that way and see it and the rest of their museum.
 
pontus said:
The box is physically shorter. It only fits one Omnibus backplane. The 8/e fits two. If i recall correctly one backplane is 20 slots. A basic PDP-8/e or 8/m would have 1 slot taken for the front panel, 4 slots for the basic CPU, 3 slots for each board of core memory (either 4kW or 8kW). You probably want a serial interface, that is 1 slot, you also need a 1 slot RFI shield between memory and other cards. So that is 10 slots for a very basic system. Extended memory requires "Extended Memory and Time Share Control" which is one slot. You might want "Extended arithmetic element" which is 2 slots. This leave you with 7 slots for more memory and peripherals. If you satisfy with an RX floppy controller you could put two extra sets of memory in there, for a maximum of 24kW. Not at all a bad machine. But if you want an RK05 controller and full 32kW of memory, you need another backplane.

(I'm no expert in configuring the PDP-8, I might very well have missed details. This was just to give a hint of what available/needed)
Click to expand...
Thought the CPU was 3 cards. And you can always use MOS
memory (like Lou did) to give yourself 32k on one card. BUt I agree one blackplane gets full rather fast.
 
tradde said:
Thought the CPU was 3 cards.
Click to expand...
I included:
  • M8300 KK8E Major registers
  • M8310 KK8E Major register control
  • M8320 KK8E Bus loads
  • M8330 KK8E Timing board, replaces M833
The "Bus loads" isn't really part of the CPU, but I think you do need it in a functioning system?
 
I looked up the card numbers in the seller's tabulated list as a learning experience:

Card NumberCard Description
M8330KK8-E CPU, CPU timing generator
M8310KK8-E CPU, CPU major registers control
M8300KK8-E CPU, CPU major registers
Y083?
Y084?
Device 50 I/O Card?
Device 51 I/O Card?
Y111?
M8650KL8-E Teletype control
M837KM8-E/MC8-E, Memory extension and time share
M849KK8-E CPU, Memory shield
G111MM8-EJ Core sense/inhibit (part of H212)
H212MM8-EJ Core memory 8k stack
G233MM8-EJ Core x-y drives 8k (part of H212)
M8320KK8-E CPU, Omnibus loads (bus terminator)

Sources:
 
pontus said:
I included:
  • M8300 KK8E Major registers
  • M8310 KK8E Major register control
  • M8320 KK8E Bus loads
  • M8330 KK8E Timing board, replaces M833
The "Bus loads" isn't really part of the CPU, but I think you do need it in a functioning system?
Click to expand...
Very true. I had not been including that.
 
The same seller has now listed a PDP-8/A system with auction and buy it now prices. I wonder if they have any other goodies waiting to be listed?
 
Looks like I'm a PDP-8/M collector now! I wonder what my chances are of finding a TU56 and some usable DECtape media to go with it? I'll need to procure a key for the power switch.
 
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