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DECTAPES and LINCTAPES, a pile of

gnupublic

gnupublic

Experienced Member
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Jan 23, 2019
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Germany, Berlin
Got some DECTAPES and LINCTAPES.

1739638918020.jpeg

The 5 stacks left in the front of the picture are PDP8 format. I read them in with DUMPTD8E without any bad block. There seem to be some quite interesting titles on it. A lot of sources, even from TSS8 I think. Maybe it's worth a look. The files are attached in simh DT format.

The DECTAPE stacks in the back are PDP11 or other formats. I'm not able to read. The green tapes are LINCTAPES. But they are not in such a good shape. The paper in the can is often bad. I'm also not able to read them at the moment, until I have my PDP12 running. And this is still far away.

If someone is interested in some of the tapes, please send me a message. I'm located in Europe. I sell them to help the owner, who needs the money.

Have fun,
Volker
 

Attachments

We have a working PDP-12 that seems to be able to read tapes just fine, and we are interested in tapes for students to use. I'll DM you.
 
LINCtape uses a reduced set of mark track codes, which I think are 4 bits instead of 6. I think the TD8E could handle it, but I haven't studied it closely.

This is different than the other DECtape formats, which all use the same mark track codes.
 
djg said:
In here https://www.pdp8online.com/ftp/software/dumprest/ is dumptd8e_18 which should be able to dump them.
Click to expand...
I will give it a try tomorrow. That's quite interesting, because I also have some other tapes from a PDP11 developer that might be great.

Do you also know a solution for the LINCTAPES? I still have about 150 Linctapes that came with my PDP12 that have to be dumped....
 
the big difference between LINC and DECtape (besides the tape moving right to left on LINCtape) is the mark track coding works in either direction because it encodes the same except it is the obverse compliment in the reverse direction, so a DECtape can read in both directions
something that DEC patented, which is why other companies only made LINCtape clones.
 
I have a recollection that Josh Dersch was able to read LINCtapes at LCM with an 8/E and a TD8E, but perhaps he was just reading 18-bit DECtapes and my memory is just fuzzy...
 
gnupublic said:
Do you also know a solution for the LINCTAPES? I still have about 150 Linctapes that came with my PDP12 that have to be dumped...
Click to expand...
Is the 12 working? I'm not sure if any of the 12 folks have written a dump program. Shouldn't be that hard to write. With that many tapes you would want to modify your console port to higher baud rate or make something to connect to one of the other interfaces for higher speed.
 
djg said:
May need constants changed to match 11 format.
Click to expand...
Looks like PDP-11 uses same format as PDP-10 so should work. Warning comments in the pal file are wrong in spots It dump 578 blocks of 384 12 bit words which is 256 18 bit words.
 
For taping LINCTAPE with PDP12 I found this on Vince's side:
https://svn.so-much-stuff.com/svn/trunk/pdp8/src/pdp12/JayJaeger/

Does anybody knowes the title of the two PDP8 tapes:
d18 DEC-08-OTS8A-A-UA4
d19 DEC-08-OTS8A-A-UA3
Looks like being sources from TSS8.

There are also lots of PA files with RTS-8 in the comments. But thee tapes are copys, no originals, and often without any label or lettering.
 
I was able to compile dumptd8e.c on my debian system and dumped 5 tapes as a test. (attached)

But I'm not able to see anything on them with PUTR.
Could only mount with /TU56 /RT11 or /XXDP without getting errors. But the listings did not seem to be valid. (No /files11 or /rstse)
I do not have a running simh with tc11 and system beeing able to use it.

So maybe somebody else may have a look into this files?

I don't expect them to be very interesting, because it looks more like beeing data backups. No system files.
 

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That code is dumping in PDP-8 format of 12 bits in 16 bit words.

0000000 0bff 0fff 0fff 0fff 0fff 0fff 0fff 0fff

Simh mounts them as 18/36b format as default so that won't work.

PDP-1/4/7/9/15 DECtapes use 578 blocks of 256 32b
words. Each 32b word contains 18b (6 lines) of data. PDP-11 DECtapes use 578 blocks of 256 16b words.
Each 16b word contains 6 lines of data, with 2b omitted.

You can try specifying 12b mode
att tc0 -t 04.18.d
 
Missed that you don't have useful. Did find a PDP-11 tape I dumped (probably with a different dump program) and it had same size as your files without .dt. Not sure what the .dt files are. If I converted the file to PDP-11 16bit format putr gave a directory. PDP-11 tapes normally don't use the upper 2 bits of the 18 bit word and the sample I had those bits were zero. Your tape has them set often. Do the labels indicate what is on the tape? Any clearly should have PDP-11 filesystem so we can verify dump is working?

Looks like people did use this code from old emails. Some modified the C program to dump in other formats.
 

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pbirkel@gmail.com said:
More generally, can a DECtape "certified" for use with a PDP-11 (or simply having been used with a PDP-11) be repurposed for use with a TD8E? If so, how? What limitations would exist in doing so?
Click to expand...
Just remark it and it should be fine.
 
gnupublic said:
For taping LINCTAPE with PDP12 I found this on Vince's side:
https://svn.so-much-stuff.com/svn/trunk/pdp8/src/pdp12/JayJaeger/

Does anybody knowes the title of the two PDP8 tapes:
d18 DEC-08-OTS8A-A-UA4
d19 DEC-08-OTS8A-A-UA3
Looks like being sources from TSS8.

There are also lots of PA files with RTS-8 in the comments. But thee tapes are copys, no originals, and often without any label or lettering.
Click to expand...
those would be tapes 4 and 3 of the set
http://bitsavers.org/bits/DEC/pdp8/tss8/TSS8 is everything I know of that I was able to find. I've never seen real distribution tapes

they only distributed the monitor on paper and they didn't distribute basic sources. I found the basic source on some tapes from UW-Milwaukee
 
In 40 years of searching, this is the first time of anyone finding original source DECtapes for TSS/8
What is on bitsavers is what John Wison and I were able to recover in the 00s.
The two tapes he read contain a lot of utililites that have never been found, quite the amazing find.
 
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