RE: Old PDP11 Tapes

[Bob & Cecelia <n3lym@amsat.org>]

Hi Eric,

Yes, the RSTS simulation is kinda like stepping into a time machine, eh?

As far as your tapes, the prevailing theory around here is that 20+ year old 
tapes are likely to be unreadable. However, I can't say that I have tried. All 
of the tapes I was able to locate from Project Delta were 800 bpi, and I never 
did find an 800 bpi  drive that was still in service.

However, I had given this some thought. If the tapes were readable, you would 
want to make tape image files that simulator can attach to and use like the 
original tape. The simulator used a special file format for tape to indicate 
file marks and eot, so you would need to write a custom program to read the 
tapes. I tried this a while back by modifying a version tcopy, if memory 
serves me correctly. The comments in this pdp11_tm.c describe the tape image 
file format. The program reads the physical tape and makes a simulator-ready 
tape image file. I tested it with tar on the Unix V7 system and it appeared to 
work. Let me know if you are interested and I can send you a copy.

The second step would be to actually read the tape image files under RSTS. 
Hopefully you remember how the tapes were made. I am especially foggy when it 
comes to all of the backup programs that we had on Delta.

I have access to 1600 bpi 9-track drives at a client where I am currently 
working, so if you want to send me the tapes, I could try it. Of course, I'm 
making no guarantees whatsoever! Alternatively, you may be able to find a 
commercial service in your local area. Generally, the companies that provided 
disaster recovery services and archival storage and such are a good place to 
start.

RSTS list people... any ideas for Eric, here? Rich, didn't you find a company 
that quoted you a price?

-Bob


-----Original Message-----
From:	Eric Parker [SMTP:eparker@zyvex.com]
Sent:	Monday, August 30, 1999 11:00 AM
To:	delta@mcws.net
Subject:	Old PDP11 Tapes

I cut my teeth on the PDP11 under RSTS/E many years ago at SMU in Dallas.  I
hung around
the machine so much that they finally made me system manager!  I wrote all
kinds of programs back then: text editor, flight simulator, hidden line
removal, macro language, PROLOG
interpreter, Pascal Compiler, digital circuit design, raster graphics
package (GENISCO),
drivers for SI disk drive, Megatek 7000 series, and on and on.  When I
graduated I put all
that stuff on 3 1600 bpi tapes which are currently sitting in boxes in my
garage.  I downloaded
your RSTS/E and PDP11 emulator and it really jogged some long dormant brain
pathways!  Now what
I'd like to do is copy the contents of those old tapes.  Do you know of any
service that can
do this?

Thanks for your attention,

Eric Parker
Zyvex LLC
eparker@zyvex.com
972 235 7881 x212