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What is a fare price for a PDP-8/e?

decmate can be fun too

decmate can be fun too

The front panel lights on a real 8/e or 11/20 (11/45, 11/70...) can be neat, but chances are, once you get the machine going with an operating system, you won't be using the programmer's console (front panel) much.

So, I think the 11/23 in the last post is an excellent way to get into 11s without breaking the bank. The q-bus cards (for 11/23,53,73,83,93) show up on ebay at reasonable prices too.

If you really want an 8, every so often on craigslist I see decmates. They use the 8-on-a-chip 6120, just like the SBC6120. No blinking lights, and a little slower than an 8/e, but it still can run OS/8 and has a nice compact VT100 style case. The 8" floppy drives you'll need (RX01/2) are a little bulky, but can serve (in one configuration: RX02-PA) as the pedistal to hold the machine at typewriter stand height.

Lou
 
I've seen DecMates on ebay also. They all seem to have 5" floppies (a few later models had hard drives). Can they boot a usable OS from floppies, or is a hard drive required?

I'm trying to locate a 6120 chip to build the PDP-8 clone from Spare Time gizmos. Seems a shame to tear apart a DecMate or something else just to get the chips.

As for the 11/23 and 11/04 on ebay... fond memories of RSTS/E...

-Crawford
 
Crawford,

The decmates with the 5-1/4" drives (dec RX50) are "decmate II" or "decmate III". They can run from the RX50. They run OS/278 and a word processor called WPS. Although I don't have one of these decmates, I think I have a set of WPS RX50s. If you want to see the original decmate, there's a picture of one in my album.

The 6120 is hard to find. I have a decmate (the original one, VT-278) that fell victim to an owner who stripped it of its 6120 to build the Gizmos board. I got it when I got my working decmate. It's really a shame, because everything's there except the 6120! It's particularly tough for someone like me who likes to restore systems (not turn them into junk.) I too would like to find some of these processors.

Lou
 
6120 Tinaja hunt

6120 Tinaja hunt

Lou,

Thanks for the info. I've been trolling ebay and the IC re-sellers for a 6120, but wonder about trying to buy something from them. (Anyone bought from those sites that *always* show up in whatever Google list, claiming to have every IC ever made?)

I'll report what I find out.

I heard that some have hacked DEC OS's to run on other hardware. I would guess that a DECMate would be an desktop PDP-8 if it could run any PDP-8 OS.

Cheers,
Crawford
 
6120 from resellers

6120 from resellers

Crawford,

I too have seen those companies that stock old devices (like Rochester Electronics) but haven't asked for a quote. I have seen that most have $250 minimum orders. I'm also afraid that they'll want big $$ per device (to make up for all the years that they had to keep that inventory around with noone to buy it.) I asked Bob from Gizmos a few months back about where he thought they might be found, and he mentioned those old device houses also. I would be willing to chip in if devices could be bought for a reasonable sum and it was a matter of getting enough intersted people to meet the minimum order amount.

As for running OS/8 on something other than an 8 (or VT78 or decmate), there's no hack to it. Basically some folks much more talented than I have written emulators under which OS/8 will run. I'm most familiar with WinEight from Gizmos. At the moment, I'm sitting on the couch with my dell laptop, and for the heck of it, just started WinEight, booted OS/8 from a virtual RX01, and did a directory.

The decmate really is a desktop 8. However, there is an unfortunate minor difference that makes it so that the same OS/8 V3D that runs on my 8/e does not run on the decmate. My original decmate runs OS/78. The main difference has to do with the way the console interface is handled. The 8/e has a serial terminal (teletype) interface that has specific device codes for sending and receiving from whatever terminal you connect as a console. The decmate however is basically a computer housed inside a terminal, and the 6120 not only does the work of an 8, but also runs the terminal. Code that runs on the decmate does not interface with the terminal functionality the way that the code would on the 8. The extra burden on the 6120 of running the terminal also means that 8 software runs slower (the 8/e is noticably faster than the decmate.)

I am by no means as knowledgeable as most of the other fellows with 8s who read alt.sys.pdp8. I've only really been serious for 3 years. I have a junior technician level of understanding, which fortunately is enough to repair the machines when they break. I did also build and trouleshoot a 32K solid state memory from the schematics of a real expert. Perhaps in ten years I'll have a true appreciation for these machines.

Lou
 
It would sure be nice if spare time gizmos would do _yet_ another run of the SBC6120. I would happily chip on that. However I guess that you would not only have to convince the nice gizmo people to put in the effort, you would also have to find a sufficiently large number of people to be willing to chip in. (Might not be so hard, given the 8 related traffic on this forum lately )
 
No luck finding 6120

No luck finding 6120

So for the heck of it, I sent an inquiry for pricing on qty. four Harris 6120s to Oxygen Electronics in White Plains. Their website says they have 302 of them. Absolutely no response this week at all. I guess we little people aren't worth the trouble. It reminds me of the response I didn't get from Athana last time I asked them for pricing on 8" floppies......

Lou
 
I'll try to find som 6120's also

I'll try to find som 6120's also

Folks,

I'll try to chase down some of the 6120 sources also. If there's a minimum order, perhaps I can swing it and ebay what the folks here do not want. I'll let you know.

-C
 
Source of HD6120s?

Source of HD6120s?

Did anyone find a source for the HD6120s, or maybe have one on-hand they would be willing to sell? I'm also attempting to request a quote from Qxygen Electronics. We'll see.... :mrgreen:
 
The sellers like Oxygen are pretty much just middlemen for the Chinese IC scavengers. They have lists of people with something to sell, but just because they advertise that they have it, doesn't mean that they really have any physical inventory.

What you're most likely to get are "pulls" in an unknown condition. If it's a popular IC, you could also get forgeries--similarly packaged ICs overpainted with the desired part number.

I've been surprised to see advertisements for mask-programmed ROMs from these vendors. How do they know what's in one?
 
middlemen

middlemen

Those guys are irritating. They also seem to have all the custom logic chips that no one else has, or even remembers who made it. They have links to the supposed datasheets that go nowhere, all kinds of garbage. Like Chuck(G) said, you'll get untested pulls or forgeries.
They're almost as bad as some of the guys that sell "refurbished" lab & test equipment on LabX.
patscc
 
Ultimately, the solution for general use will probably have to take the form of programmable logic I wonder if the design could be shoehorned into a couple of CPLDs? Failing that, there's always FPGA...
 
Gal

Gal

Wasn't the original Harris 6120 a GAL-based design, anyway ?
I wiki'd DEC, and it states that the chip business went to Intel and the PDP-11 rights went to Mentec after DEC folded.
I wonder who got the design for the 6120 or if a copy still exists at Harris ?
patscc
 
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