General question -- Reading PDP-11 tape reels.

[kenjennings]

Not Atari-specific, but I've read about people here pulling thing off Atari's mainframe tapes. Was wondering if anyone has the resources to assist in another project.

 

I'm discussing getting source code for GRASS/ZGRASS from the author. He reports he has "9-track tape/source code in .rol format for PDP-11 assembler". Does anyone here have the ability to read this? Is there other information you need to be sure?

 

I'm not certain yet how we would transfer possession of the tape or under what terms he would part with it. Just trying to find out if there is someone out there who can do something useful with it.

 

Thanks.

 

[Rybags]

Is the tape for a Dectape https://en.wikipedia.org/wiki/DECtape

or is it a larger type 9-track?

 

There's a large degree of commonality for the 9-track 1600 and 6250 bpi types. I used to work in mainframe operations in the day and before cartridges became common in the late 80s, 6250 was the standard but 1600 was also common especially for data interchange with other systems esp minis such as the PDP-11.

 

It would be interesting to build a modern-day method to read these tapes. I suspect most of the actual drives are long gone, one problem is that a lot of them probably wouldn't work on domestic power, a lot of the heavy iron worked on (I think... ) 415 Volts multi-phase AC. Aside from that, tape drives are bulky and by the mid 90s had more value in scrap than it was worth keeping them around.

 

A modern day interface would have to be low speed - the top speed of the old tape drives was something like 15 feet/second when seeking and even general read speeds were pretty quick.

A stopping point might be getting read heads. The tape used I'm fairly sure was the same width as VHS but videotapes use helical scan whereas reel to reel used the old fashioned data tracks.

 

 

Possibly there's data conversion businesses around that could handle it. Though that would mean sending the media away.

[greblus]

I've seen a similar story in the em400 Mera400 emulator & preservation project. The author received tapes from the CROOK operating

system authors (and many others sources too) and he was struggling to have them restored, with a great success at the end.

 

To make the long story short, he's sent the tapes to the italian Museo dell'Informatica Funzionante.They read the tapes and he was

working on the images using the software he created for that purpose:

 

https://github.com/jakubfi/ninetracklab

 

There are lots of interesting info on Mera400 Facebook page:

 

https://www.facebook.com/mera400/

 

And I'm sure the author might help in this case (very clever and nice guy).

 

W.

[Mechanicjay]

Not Atari-specific, but I've read about people here pulling thing off Atari's mainframe tapes. Was wondering if anyone has the resources to assist in another project.

 

I'm discussing getting source code for GRASS/ZGRASS from the author. He reports he has "9-track tape/source code in .rol format for PDP-11 assembler". Does anyone here have the ability to read this? Is there other information you need to be sure?

 

I'm not certain yet how we would transfer possession of the tape or under what terms he would part with it. Just trying to find out if there is someone out there who can do something useful with it.

 

Thanks.

 

 

I don't but I know there are quite a number of PDP-11 folks around -- some resources to find them:

 

1) Go check the DEC forum at http://www.vcfed.org/forum/forumdisplay.php?23-DEC

 

2) Go chat in the #classiccmp IRC channel on freenode.net

 

3) Check out the cctalk mailing list at http://www.classiccmp.org/cctalk.html-- this can be quite verbose, but there's tons of expertise there.

 

--Jason