What were the DT8-E modules?

[ftcnet]

I see mention of these three early serial Omnibus options (DT8-EA, DT8-EB and DT8-EC). Were these ever produced (did M83xx module numbers get assigned)? Are there any references to them in any software or documentation? I'm curious if anyone has ever seen these Omnibus serial options? Did Charlie Lasner mention them?

Source document: 081X 00770 AOG B 02 30 PDP8/E (43 Mb) on p. 20

 

[gnupublic]

I liked this document that much, that I made a poster of it some month ago. I came to the same question. But even if they made some of this interfaces, they will be hard to find.

 

[DougIngraham]

This is a good question. I used an 8/e timeshare system when I was in High School in 1973 via an acoustic coupled Teletype 33. That machine had some way of reporting the number of users. I remember that when it said it had less than 15 users it was usable for editing but as soon as it got to 15 it would fall flat on its face. There would be several seconds between the time you pressed a key and the echo of that character. I wouldn't bother even trying to use it when reported high numbers. The yellow paper they used in the Teletype all rotted away years ago so I don't have any of those printouts anymore. That yellow paper is kind of like the DEC foam.
I never saw this machine but I was told it had 24k of memory and a drum device for swapping and storage. The question would be what did they use to talk to the remote terminals? If it was three of the DT8-EA boards then there should only have been a max of 13 terminals (3 DT8-EA boards times 4 terminals plus the console port.)

I have one of the KL8A (M8319) boards in my collection. This is a 4 port hex board. I think it was in the machine I got from a company that used it for accounting for their photo processing business. I am pretty sure Vince has a KL8A as well.

I am trying to download the source document mentioned but that site is really slow. Looks like it is going to take a couple of hours. How many of you all are trying to download it at the same time?

 

[m_thompson]

M838 ASYNCHRONOUS CONTROL FOR DT8-E

I didn't find any mention of a DT8/E in the OS/8 or P?S/8 documentation.

 

[Bitly]

M838 ASYNCHRONOUS CONTROL FOR DT8-E

I didn't find any mention of a DT8/E in the OS/8 or P?S/8 documentation.

In the 1973 Options and Modules List, the M838 is status '7' - Obsolete and connot be built.

Since the PDP-8/E was released in 1970, the DT8/E didn't live for very long...

CW

 

[ftcnet]

Thanks for the useful replies. I find it interesting that I keep finding mentions of Omnibus options that I never heard of while employed at DEC for 8+ years as regional tech support for 12-bit products. I've been onsite at hundreds of customer sites. I spent 3-4 months at various DEC field-service training facilities in MA learning how to maintain the 8I, 8L, 8E,F,M, 8A product line. None of the instructors or other DEC field techs ever mentioned these 'rare' options.

There must have been some serious issues with the DT8-E modules. Maybe they were only compatible with the original KK8E that used 3-digit CPU modules (M833, M830, M831, M832)? The same engineer 'RBR' was responsible for DP8-E sync intf. was also responsible for the DT8-E.

As DougIngraham mentioned, it seems the DT8-E options were possibly meant for the EduSystem market, but nothing comparable to the DT8-E's came available until the KL8-A was released. I don't think KL8-A's were ever used with EduSystems.

The 1973 Options and Modules List doesn't identify which DT8-E option (A, B or C) the M838 was, but I assume it was the DT8-EA (4 port).
CESI did produce a QUADART Omnibus module that had most of the capability of the KL8-A (on a quad module) and seems similar to the DT8-EA.
The DT8-EB seems functionally similar to the KL8-M (M8653 modem control option) except the DT8-EB handled 4 lines.
I think Mike_Z would be interested in seeing the DT8-EC schematic, since it sounds like it provided selectable baud rates for serial ports.