PDP 11/73 is ALIVE!

From: Ian Primus <ian_primus_at_yahoo.com>
Date: Mon Nov 24 06:18:42 2003

On Monday, November 24, 2003, at 04:46 AM, Fred N. van Kempen wrote:
>
> Since the "*** THIS VOLUME" ... comes from the boot loader (it is not
> in the bootstrap program...) on tape, we *did* load something from it.

OK, that's good, I was worried that the tape drive might be damaged, or
have dirty heads or something.

> Dunno which tape you are using, but: the address the boot loader uses
> is that of the TM11/TS11. The instruction (100001) it sends to the
> controller doesn't match that of the TM11, so it must be the TS11 it
> thinks it has- and this is quite often the case with Emulex and Dilog
> controllers.

I tried three different tapes, two of which are the same thing. One
tape is a homemade system tape, on an ten inch reel. The label is
handwritten in pencil and hard to read. It says "RSX-11-M-Plus V4.0
Operating system for Eagle (DB2, omitting software directories) VMR'd
for extra pool space <something I can't read>, needs DTR files
[1,2],<something else I can't read>" The other tape is an official
Digital tape on a 12 inch reel. The label says "BB-JO81J-BC
RSX-11M-LUS V4.4 BRU MT:1/1 ID:RSX11MPBL78 DIST 1600BPI COPYRIGHT
1993 DIGITAL EQUIPMENT CORPORATION MB0804". I don't know what
controller these were written for, or how my Emulex card is set up.
I'll have to read through the Emulex manual some more.

> Even though we were able to load the secondary bootstrap off tape
> (which
> is blocks 0 and/or 1 on tape), we **ALSO** need to have that code know
> what we're loading from.
Are these leading blocks written in the same format or a different
format as the rest of the tape? What about density? I'll have to look
up in the manual, but I _think_ the default on my drive is 1600bpi, but
I'm not positive.

> Suppose... we load the secondary boot. But: that thinks we're using a
> TM11 controller. It then tries to load the rest off tape... but barfs,
> because the TM11 doesnt respond (since it's really a TS11.) ... error..

What's the difference between the two controllers? Is their tape format
different, or just the headers?

>> I might end up doing that, I can write down the output, and email it
>> to
>> you.
> Use a terminal program on a PC or other system, and just log the
> sessions. Much easier :)
Good point... Right now I'm using a Lear Siegler ADM3A :)

>> I have two blank tapes, as well as the SCSI nine track tape drive that
>> goes with my Prime. I should be able to connect the other tape drive
>> to
>> a PC, and dd a tape image to a real tape. Is there a known working,
>> bootable tape image out there on the 'net that I could use to test?
> Sure, whatcha want? I can send you the Ultrix-11 mini root, which is
> very small, and which will tell you whether things work or not..
Yeah, that would be great. Is there anything special I have to do when
I write the tape to make sure the PDP-11 can read it? Since the tape
drives are different (the PDP-11 one is Pertec, the Prime one is SCSI),
will the tapes be compatible? It sounds like tapes written with two
slightly different Pertec controllers on the PDP-11 aren't compatible.


Ian Primus
ian_primus_at_yahoo.com
Received on Mon Nov 24 2003 - 06:18:42 GMT

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